tag:theconversation.com,2011:/uk/topics/mitochondrial-dna-2245/articlesMitochondrial DNA – The Conversation2023-08-18T12:39:32Ztag:theconversation.com,2011:article/2115892023-08-18T12:39:32Z2023-08-18T12:39:32ZIdentifying fire victims through DNA analysis can be challenging − a geneticist explains what forensics is learning from archaeology<figure><img src="https://images.theconversation.com/files/543315/original/file-20230817-17-h1y2zw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1024%2C683&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Identifying victims after a disaster can offer closure to loved ones.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/APTOPIXHawaiiFires/2b2bf672bfc14794b8fbc20138f36c62">AP Photo/Jae C. Hong</a></span></figcaption></figure><p>Fire devastates communities and families, and it makes <a href="https://doi.org/10.1111/j.1556-4029.2012.02083.x">identification of victims challenging</a>. In the aftermath of the wildfire that swept through Lahaina, Hawaii, <a href="https://www.staradvertiser.com/2023/08/14/hawaii-news/maui-families-provide-dna-to-help-id-remains-of-fire-victims/">officials are collecting DNA samples</a> from relatives of missing persons in the hope that this can aid in identifying those who died in the fire. </p>
<p>But how well does DNA hold up under such extreme conditions, and what is the best way to recover DNA from fire victims? </p>
<p>I am an <a href="https://scholar.google.com/citations?user=xqKVKIwAAAAJ&hl=en">anthropological geneticist</a> who studies degraded DNA in archaeological and forensic contexts. <a href="https://stone.lab.asu.edu">My research group</a> applies ancient DNA and forensic analysis methods to optimize DNA recovery from burned bones. Retrieving DNA from severely burned remains in order to identify victims is a particular challenge.</p>
<h2>Forensic DNA analysis</h2>
<p>In a typical forensic investigation, <a href="https://www.forensicsciencesimplified.org/dna/how.html">DNA is extracted</a> from a sample – whether some blood, pieces of tissue or bone – collected from the scene of the disaster or crime. This process chemically separates the DNA from other components of cells within the sample, such as proteins, and purifies it. </p>
<p>This DNA is used as a template for <a href="https://www.genome.gov/about-genomics/fact-sheets/Polymerase-Chain-Reaction-Fact-Sheet">polymerase chain reaction, or PCR, analysis</a>, a method that is essentially the Xerox copier of molecular biology. Even if there are only a few cells present in the sample, PCR can amplify those DNA molecules into thousands or millions of copies. This creates a sufficient amount of DNA for subsequent tests.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/7onjVBsQwQ8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">DNA analysis can help identify victims by comparing genetic similarities between people.</span></figcaption>
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<p>In forensics, the specific DNA targeted in PCR is usually a set of highly repetitive markers called <a href="https://strbase-archive.nist.gov/intro.htm">microsatellites, or short tandem repeats</a>. Law enforcement agencies around the world use specific sets of these markers for identification purposes. In the U.S., forensic analysts target 20 of these DNA repeats. Each person has two unique alleles, or genetic variants, at each of these markers, and these alleles are uploaded to the FBI’s <a href="https://www.fbi.gov/how-we-can-help-you/dna-fingerprint-act-of-2005-expungement-policy/codis-and-ndis-fact-sheet">Combined DNA Index System database</a> to identify matches. </p>
<p>DNA taken from the <a href="https://namus.nij.ojp.gov/services/dna#faq-what-is-a-family-reference-sample">relatives of missing people</a> will likely be analyzed for short tandem repeat markers and their allele profiles uploaded to the Relatives of Missing Persons index within the database. The expectation is that victims and their biological relatives share a percentage of alleles for these markers. For example, parents and children share 50% of their alleles, since a child inherits half of their DNA from each parent.</p>
<h2>Challenge of degraded DNA</h2>
<p>In forensic contexts, the time between death and DNA sampling is usually short enough that the DNA is often still in fairly good shape, both in terms of quantity and quality. However, DNA is often not found in ideal conditions after a disaster. </p>
<p>Time and the elements <a href="https://doi.org/10.1080/20961790.2018.1515594">take their toll</a>. After death, the process of decomposition releases enzymes that can cleave or damage DNA, and additional damage occurs over time depending on the environment in which the body is found. DNA also degrades faster in warm, wet, acidic environments and slower in colder, drier environments that are more pH neutral or slightly basic. </p>
<p>In addition, DNA preservation may vary considerably among the tissues, bones and teeth recovered. For example, researchers found that DNA identification of victims of the <a href="https://doi.org/10.1111/j.1556-4029.2009.01045.x">World Trade Center attacks</a> in 2001 was most successful when using bones of the feet and legs, compared with bones from the head and torso.</p>
<p>DNA damage can take different forms. Nicks and breaks in the DNA make it difficult to analyze. Chemical modification of the DNA can result in changes to the original sequence or make it unreadable. This includes changes to the building blocks of DNA <a href="https://www.genome.gov/genetics-glossary/Nucleotide">called nucleotides</a> that make up an identifiable sequence. For example, exposure to water can cause a chemical reaction <a href="https://doi.org/10.1101/cshperspect.a012567">called deamination</a> that changes the nucleotide cytosine such that it appears to be the nucleotide thymine upon analysis. Exposures to other chemicals or UV light can <a href="https://chem.libretexts.org/Ancillary_Materials/Exemplars_and_Case_Studies/Exemplars/Biology/Cross-Linking_in_DNA">cause cross-linking</a>, which essentially ties the DNA into knots. As a result, the PCR enzymes used to copy or read the DNA sequence can’t move linearly along the DNA strand. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Rows of burnt houses and cars in the aftermath of the Lahaina fires." src="https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543323/original/file-20230817-33902-1dr1ti.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Exposure to intense and extended fires can make victim identification through DNA analysis difficult.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/HawaiiFires/185896ea7dfd43b99850521649cf5be6">AP Photo/Jae C. Hong</a></span>
</figcaption>
</figure>
<h2>Applying methods from archaeology</h2>
<p>Researchers encounter similar issues in handling degraded genetic material when analyzing the DNA of ancient remains that are thousands of years old. To address these challenges, forensic geneticists and ancient DNA researchers like me employ a number of tricks to <a href="https://doi.org/10.1038/s43586-020-00011-0">optimize DNA retrieval</a>.</p>
<p>First, we tend to target dense bone or teeth for sampling, since they are more impervious to the environment. We also use DNA extraction methods that enhance the recovery of short fragments of DNA. </p>
<p>Second, we use PCR to amplify even shorter genetic markers, including mini-short tandem repeats, or sections of the <a href="https://www.genome.gov/genetics-glossary/Mitochondrial-DNA">mitochondrial genome</a>. Mitochondria are structures within each cell that produce energy, and each one has its own DNA. Mitochondrial DNA is passed down from mother to child and can be found in hundreds of copies within each mitochondrion, which make it easier to recover and analyze. However, mitochondrial DNA <a href="https://doi.org/10.1146/annurev.genom.4.070802.110352">may not provide sufficient information</a> for identification, since people who are maternally related, even very distantly, will share the same sequence.</p>
<p>Researchers are also testing newer methods of DNA analysis common in the ancient DNA field for forensic purposes. For example, <a href="https://doi.org/10.1038/s43586-020-00011-0">special enzymes</a> can remove chemically modified nucleotides, such as deaminated cytosines, to prevent misreading of the DNA sequence. Researchers can also use DNA baits to “fish” for specific sequences. This method of <a href="https://doi.org/10.1038/nmeth.1419">targeted enrichment</a> can recover very small fragments that can be used to piece together the full genetic sequence.</p>
<h2>DNA analysis of burned remains</h2>
<p>For <a href="https://doi.org/10.1002/9781119682691.ch12">fire victims</a>, particularly those caught in intense, extended fires, the DNA may be highly fragmented, making analysis difficult. High temperatures cause bonds between molecules, including nucleotides, to break. This results in fragmentation and ultimately destruction of the DNA.</p>
<p>Because hard tissue – bones and teeth – are often all that remains after a fire, forensic researchers have studied how bone characteristics such as color and composition <a href="https://doi.org/10.1016/j.fsigen.2010.08.008">change with temperature</a>. My research team used this information to classify the level of burning that human bone samples have been subjected to.</p>
<p>In investigating DNA preservation in those samples, we found that there is a <a href="https://doi.org/10.1016/j.fsigen.2020.102272">significant point of DNA degradation</a> when bones reached temperatures between 662 degrees Fahrenheit (350 degrees Celsius) and 1,022 F (550 C). For comparison, <a href="https://www.cremationassociation.org/page/CremationProcess">commercial cremation</a> is 1,400 to 1,600 F (760 to 871 C) for 30 to 120 minutes, and <a href="https://doi.org/10.1016/j.csite.2017.08.001">vehicle fires</a> typically reach 1,652 degrees F (900 C) but can last a shorter period of time.</p>
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<figcaption>
<span class="caption">Survivors of the Lahaina wildfires, which began on Aug. 8, 2023, walk through the aftermath.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/HawaiiFiresPowerLines/6643e5e332e44e8e8fedbb01c15ece9c">AP Photo/Rick Bowmer</a></span>
</figcaption>
</figure>
<p>Our team also found that the likelihood of generating high-quality short tandem repeat data or mitochondrial DNA sequence data, whether using forensic or ancient DNA methods, decreases significantly at temperatures <a href="https://doi.org/10.1016/j.fsigen.2021.102610">greater than 1,022 F</a> (550 C). </p>
<p>In sum, as temperature and exposure time increase, the amount of remaining DNA decreases. This leads to only partial DNA profiles, which can limit analysts’ ability to match a victim to a relative with high statistical certainty or prevent results altogether.</p>
<p>DNA evidence is not the only method used for identification. Investigators <a href="https://doi.org/10.1016/j.forsciint.2008.09.019">combine DNA with other evidence</a> – such as dental, skeletal and contextual information – to identify a victim conclusively. Together, this information hopefully will help bring closure for families and friends.</p><img src="https://counter.theconversation.com/content/211589/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anne Stone receives funding from the National Institute of Justice. </span></em></p>Maui officials have asked relatives to provide DNA samples to help identify victims of the Lahaina wildfires. Time and exposure to the elements, however, can make DNA retrieval from remains difficult.Anne Stone, Professor of Human Evolution and Social Change, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1771912022-02-16T22:53:00Z2022-02-16T22:53:00ZA new species of flatworm in our gardens that comes from Asia: Humbertium covidum<figure><img src="https://images.theconversation.com/files/446553/original/file-20220215-21-1d169v2.png?ixlib=rb-1.1.0&rect=0%2C19%2C3199%2C1681&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The new species _Humbertium covidum_.</span> <span class="attribution"><a class="source" href="http://dx.doi.org/10.7717/peerj.12725">Pierre Gros</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>A hundred animal or plant new species are described each year in metropolitan France. In most cases, these are native species, present here for a long time, but which had so far escaped the attention of scientists. In a very different way, <a href="https://peerj.com/articles/12725/">we are now reporting</a> the existence of a new species found in France, but which has been introduced, and which is even potentially capable of invading our gardens.</p>
<p>This species is a flatworm, the size of one knuckle of your little finger. The species is elongated, with a broader head, like all hammer-headed flatworms. Its colour is quite extraordinary: totally black, it is reminiscent of “liquid metal”. Its name: <em>Humbertium covidum</em> – we will come back to this name later.</p>
<h2>How to tell the species apart?</h2>
<p>For about ten years, we have known that flatworms have invaded the gardens of France. Our team thus reported and mapped the invasion by several species: <a href="https://peerj.com/articles/1037/">the New Guinea flatworm</a> (<em>Platydemus manokwari</em>), the <a href="https://peerj.com/articles/4672/">giant hammerhead worms</a> (especially <em>Bipalium kewense</em>) and the oddly named <em>Obama nungara</em>, which alone has invaded <a href="https://peerj.com/articles/8385/">more than 70 departments in France</a>. We have also reported recent invasions <a href="https://doi.org/10.11646/zootaxa.4951.2.11">overseas</a>.</p>
<p>To give a <a href="https://en.wikipedia.org/wiki/International_Code_of_Zoological_Nomenclature">name to a species</a>, scientists must be convinced that the species is new, and therefore explain how it is different from already known species. In all cases, the shape and colour of the organism must be accurately described. Very often, it is also necessary to precisely describe the sexual organs of the species, which are characteristic and different from other species. This is where a problem arises for flatworms: some species only reproduce asexually, and therefore simply do not have sex organs. One can imagine the problem of how then to differentiate them. This is why we used modern molecular biology techniques to characterise the mitochondrial genomes of these species.</p>
<h2>The mitochondrial genome</h2>
<p>The <a href="https://en.wikipedia.org/wiki/Mitochondrial_DNA">mitochondrial genome</a>, abbreviated as mitogenome, is the genetic code that makes the mitochondria work, small organelles that are in their thousands and are the energy powerhouses in all cells. As this mitochondrial genome is present in millions of copies in an animal, it is therefore technically easier – and less expensive – to obtain it than the genome of the nucleus. The mitochondrial genome is circular DNA, about 15,000 nucleotide base pairs long: long enough to give a lot of information, and short enough to be easily obtained.</p>
<p>We therefore obtained the mitochondrial genome of several species of invasive flatworms, such as that of the <a href="https://doi.org/10.1080/23802359.2020.1748532">New Guinea flatworm</a> and <a href="https://doi.org/10.1080/23802359.2019.1596768">hammerhead worms</a>. We used the characteristics of these genomes to differentiate the species found, even if they had no visible sexual characteristics.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=594&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=594&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=594&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=747&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=747&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=747&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The mitochondrial genome of the new species <em>Humbertium covidum</em>.</span>
<span class="attribution"><span class="source">Justine et al., 2022</span></span>
</figcaption>
</figure>
<h2>The new species in France</h2>
<p><a href="https://peerj.com/articles/12725/">We found the new “metallic black” species</a> in two gardens in France, both in the department of <a href="https://en.wikipedia.org/wiki/Pyr%C3%A9n%C3%A9es-Atlantiques">Pyrénées-Atlantiques</a>, in communes separated by a hundred kilometres. It is now well known that the department of Pyrénées-Atlantiques is a <a href="https://peerj.com/articles/4672/">small paradise for flatworms</a> introduced from all over the world, mainly because of its mild and always somewhat humid climate. In both cases, there were only a few individuals of the black species. </p>
<p>At the beginning of our study, we even wondered if they were not simple black variants of a larger species, <em>Bipalium kewense</em>, also found in these gardens. But close examination of the specimen morphology and genome, and comparison of these with other species, there was no doubt that the black species was different. We then looked in the scientific literature if the species had been described elsewhere, and especially in tropical Asia, which is the main continent of origin of these hammerhead worms. We did find a few reports of animals that look like it, but nothing more.</p>
<h2>Also in Italy</h2>
<p>Toward the end of 2019, we were warned that a black species was proliferating in a field in <a href="https://en.wikipedia.org/wiki/Veneto">Veneto</a>. Hundreds of black worms, very active early in the morning, and very mobile. <a href="https://doi.org/10.1007/s10530-021-02638-w">Other reports</a> were then made of this black worm near Rome. We compared the mitochondrial genome of individuals found in France with that of individuals found in Italy: they were very little different, which shows that they are the same species, which was therefore already present in two countries in Europe.</p>
<p>And so, it was necessary to describe the species, that is to say, to give it a <a href="https://en.wikipedia.org/wiki/International_Code_of_Zoological_Nomenclature">Latin name</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/PwXlwyXAiIU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The new species <em>Humbertium covidum</em>, filmed in Italy.</span></figcaption>
</figure>
<h2>The name of the new species</h2>
<p>Assigning a name to a species is an essential and essential key step for any subsequent study. When dealing with potentially invasive species, and which therefore may attract the attention of the legislator, it is even more essential to be able to name them: the laws and decrees use Latin names, because these names guarantee that we correctly designate the right species.</p>
<p>Each Latin species name is binomial, with a genus name and a species name. For the genus name, it is “Humbertium”, simply because the animal has the characters of <a href="https://biblio.naturalsciences.be/associated_publications/bjz/bibliographic-references/ISI_000170313800034">this genus described in 2001</a>. For the name of the new species, we have chosen “<em>covidum</em>”, a name obviously based on “Covid”, the virus. Why? First, because we started this work in 2020, when our laboratories were in the <a href="https://en.wikipedia.org/wiki/COVID-19_lockdowns">Covid pandemic regulatory lockdown</a>. Then, as the pandemic progressed, we wanted to name the species to honour of all the victims. And finally, it seemed to us that “<em>covidum</em>” was an appropriate name for an organism capable of invading the world and coming from Asia, like <a href="https://en.wikipedia.org/wiki/COVID-19_pandemic">the Covid-19 pandemic</a> itself.</p>
<h2>Invasive species</h2>
<p>Apart from <a href="https://peerj.com/articles/12725/">the description of this single species</a>, what does this discovery of a new species of flatworm in Europe tell us? Above all, that foreign species are constantly invading our regions (the same thing exists elsewhere in the world, with European species invading other continents). Should we blame them and hold them responsible? These species have nothing to do with it, of course. It is humanity that is responsible, and in particular the modern phenomenon of <a href="https://en.wikipedia.org/wiki/Globalization">globalisation</a>, by which goods are circulated at a breakneck pace in all directions. A few individuals of a flatworm, who do not realise anything, find themselves crossing the whole world in a few days, probably in the soil of a lot of plants. They arrive in a new environment where their natural enemies are absent, find abundant food, and proliferate. In the case of <em>Humbertium covidum</em>, by analysing the DNA of their prey, we were able to show that the species eats small snails, but it may also consume other prey.</p>
<p>How is this arrival of <em>Humbertium covidum</em> a problem? Because the animal species that live on and in the ground have been in balance with their European environment for a long time, and the arrival of an opportunistic predator can change this balance, and therefore alter the <a href="https://en.wikipedia.org/wiki/Biodiversity">biodiversity</a> of our soils. Altering biodiversity has an ecological cost, and even an economic cost. For example, we can calculate that invasive species reduce agricultural production. The cost of invasive alien species in France is enormous, in the order of <a href="https://doi.org/10.3897/neobiota.67.59134">hundreds of millions of euros</a> per year.</p>
<p><em>Humbertium covidum</em> is therefore <a href="https://peerj.com/articles/12725/">one more example of an introduced species</a>, which ultimately threatens biodiversity. Hopefully, unlike the virus that gave it its name, it doesn’t take over the world.</p><img src="https://counter.theconversation.com/content/177191/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jean-Lou Justine has received funding from the Muséum National d'Histoire Naturelle. He is one of the "Academic Editor" (volunteer) of the scientific journal PeerJ in which this research is published.</span></em></p><p class="fine-print"><em><span>Leigh Winsor ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>A new species of flatworm is invading us. It is metallic black in color and its name is Humbertium covidum.Jean-Lou Justine, Professeur, UMR ISYEB (Institut de Systématique, Évolution, Biodiversité), Muséum national d’histoire naturelle (MNHN)Leigh Winsor, Adjunct Senior Research Fellow, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1766682022-02-08T23:37:42Z2022-02-08T23:37:42Z‘Maeve’s law’ would let IVF parents access technology to prevent mitochondrial disease. Here’s what the Senate is debating<figure><img src="https://images.theconversation.com/files/445252/original/file-20220208-23-vygwrj.png?ixlib=rb-1.1.0&rect=0%2C0%2C577%2C445&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Courtesy of Louise Hyslop & Mary Herbert, Univ. Newcastle upon Tyne</span></span></figcaption></figure><p>The Senate is this week debating “Maeve’s law” – a proposal to legalise access to new assisted reproductive techniques that will reduce the risk of parents passing on mitochondrial disease to their children.</p>
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<a href="https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Maeve and Sarah Hood" src="https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445246/original/file-20220208-36472-1c86l4h.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Maeve with her mother Sarah Hood.</span>
<span class="attribution"><span class="source">Photo courtesy of the Hood family</span>, <span class="license">Author provided</span></span>
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<p>The legislation, formally called the <a href="https://www.aph.gov.au/Parliamentary_Business/Bills_LEGislation/Bills_Search_Results/Result?bId=r6697">Mitochondrial Donation Law Reform (Maeve’s Law) Bill 2021</a>, is named after Maeve Hood, a six-year-old Victorian girl who lives with Leigh syndrome – a disorder in which the body’s cells fail to produce enough energy. Tragically, Maeve is unlikely to survive beyond childhood. </p>
<p>This week’s expected vote will be the first conscience vote in the Senate since the historic reforms to allow <a href="https://theconversation.com/australia-has-finally-achieved-marriage-equality-but-theres-a-lot-more-to-be-done-on-lgbti-rights-88488">marriage equality in 2017</a>, and is already being passionately debated. </p>
<p>But the issues raised are unlikely to be new. These reforms have already undergone <a href="https://www.nhmrc.gov.au/mitochondrial-donation-0">extensive community consultation</a> and been <a href="https://www.theguardian.com/australia-news/2021/dec/01/controversial-mitochondrial-donation-legalised-after-conscience-vote">approved by the House of Representatives</a>. </p>
<h2>What is mitochondrial donation?</h2>
<p>Mitochondria are energy-producing structures inside cells, which have their own DNA and are separate from the cell nucleus containing the bulk of the cell’s DNA (called “nuclear DNA”). Mitochondrial DNA is inherited entirely from the mother’s egg, so if a mother has mutations in her mitochondrial DNA she is at risk of passing life-threatening conditions to her baby.</p>
<p>Conceiving a baby via mitochondrial donation involves implanting the mother’s nuclear DNA into a healthy egg from which the nuclear genes have been removed, and using this egg for in-vitro fertilisation (IVF) with a sperm. Alternatively, a procedure called pronuclear transfer can be used early in the fertilisation process a few hours after the sperm has entered the egg, but before the parental genomes come together and the fertilised egg officially becomes an embryo. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Schematic diagram of mitochondrial donation" src="https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=584&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=584&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445254/original/file-20220208-27-x3p9ju.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=584&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="attribution"><span class="source">Mito Foundation</span></span>
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<p>A child born via mitochondrial donation would inherit a mixture of their mother’s and father’s nuclear DNA as usually occurs, along with the healthy mitochondrial DNA from the egg donor.</p>
<p>As a result, mitochondrial donation has sometimes been described as creating “three-parent babies”. But “<a href="https://theconversation.com/3-parent-ivf-could-prevent-illness-in-many-children-but-its-really-more-like-2-002-parent-ivf-126591">2.002-parent babies</a>” would arguably be more accurate, given there are only 37 mitochondrial genes, compared with at least 20,000 in our nuclear DNA.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/3-parent-ivf-could-prevent-illness-in-many-children-but-its-really-more-like-2-002-parent-ivf-126591">3-parent IVF could prevent illness in many children (but it's really more like 2.002-parent IVF)</a>
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<p>Australian law currently bans the creation of a human embryo that involves genetic material from more than two people. The ban was introduced almost 20 years ago amid fears IVF and embryo research would lead to “designer babies” and cloning. Maeve’s law would change this situation specifically to allow mitochondrial donation to prevent mitochondrial disease.</p>
<p>Debate around the issue has focused on a range of questions, such as: is there a risk the child could still end up with mutant mitochondrial DNA? Are there ethical issues centred on the unborn baby’s inability to give consent? What are the egg donor’s rights? Does the procedure carry other health or genetic risks?</p>
<h2>The expert view</h2>
<p>In the United Kingdom, where mitochondrial donation research was pioneered, four scientific reviews by the Human Fertilisation and Embryology Authority and an investigation by the Nuffield Council on Bioethics were conducted between 2011 and 2016. These reviews delivered an overall conclusion that the benefits outweigh the harms if regulated appropriately, and Britain <a href="https://theconversation.com/decision-to-allow-three-person-ivf-should-be-welcomed-37192">legalised mitochondrial donation</a> in 2015. </p>
<p>In Australia, mitochondrial donation has been considered by a <a href="https://www.nhmrc.gov.au/mitochondrial-donation-0">series of inquiries</a>, including a 2018 Senate inquiry and a National Health and Medical Research Council (NHMRC) review, which considered these issues with fresh eyes.</p>
<p>In response, the government drafted Maeve’s law, which underwent a series of reviews and public consultations, and gained the support of <a href="https://www.mcri.edu.au/sites/default/files/media/documents/mitochondrial_donation_open_letter.pdf">60 leading Australian experts</a>.</p>
<h2>Does the public support it?</h2>
<p>One challenge in gauging public support is to measure true community sentiment, rather than inviting submissions that merely serve as a forum for people with existing strongly held views either for or against mitochondrial donation.</p>
<p>To address this challenge, researchers convened a <a href="https://academic.oup.com/humrep/article/34/4/751/5377828">citizens’ jury</a> in 2017, and the NHMRC held a <a href="https://www.nhmrc.gov.au/mitochondrial-donation-0#download">citizens’ panel</a> in 2019 to evaluate attitudes to mitochondrial donation. Both offered qualified support for allowing the technology.</p>
<h2>What topics are likely to be contentious in the Senate debate?</h2>
<p>The Senate will likely revisit amendments that were defeated in the House of Representatives in December. These include a proposal only to allow the technique in which the mother’s DNA is implanted into the donor egg <em>before</em> fertilisation with the father’s sperm.</p>
<p>This suggestion is a response to fears that pronuclear transfer would lead to increased rates of embryo destruction.</p>
<p>But these early fertilised eggs – also called zygotes – do not meet the legal or biological definition of an embryo, and most embryologists do not regard this technique as leading to more loss of embryos than other assisted reproductive technologies. What’s more, banning this approach could greatly compromise the development of mitochondrial donation in Australia.</p>
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<a href="https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Zygote undergoing pronuclear transfer" src="https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=469&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=469&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=469&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=589&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=589&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445256/original/file-20220208-32038-1qki08t.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=589&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A zygote about to have its nuclear DNA removed and transferred to a donor egg, roughly 20 hours before division to form a two-cell embryo. Arrows show the mother’s and father’s DNA, called ‘pronuclei’. These remain separate until later in the process, hence why the zygote is not considered an embryo.</span>
<span class="attribution"><span class="source">Courtesy of Louise Hyslop & Mary Herbert, Univ. Newcastle upon Tyne</span></span>
</figcaption>
</figure>
<p>Maeve’s law will still require researchers to account to NHMRC for eggs and embryos used in their research, to seek ways to minimise the numbers used, and to report to Parliament on an annual basis.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/disputes-over-when-life-begins-may-block-cutting-edge-reproductive-technologies-like-mitochondrial-replacement-therapies-146254">Disputes over when life begins may block cutting-edge reproductive technologies like mitochondrial replacement therapies</a>
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<h2>If not now, when?</h2>
<p>While we need to respect differing attitudes to IVF and embryo research, we believe most experts and members of the public recognise the importance of giving couples who are at risk of mitochondrial disease the best chance of having a healthy child.</p>
<p>Maeve’s law has been carefully written to ensure a cautious introduction and evaluation of mitochondrial donation technology. The technology will be in a clinical trial setting for at least ten years, during which time the health of babies born using these techniques will be carefully monitored. </p>
<p>The science supports it. The community support it. People who are affected by mitochondrial disease have long supported it. We call on Senators to support it.</p><img src="https://counter.theconversation.com/content/176668/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Thorburn receives funding from NHMRC, MRFF, the US Department of Defense Congressionally Directed Medical Research Program, the Royal Children's Hospital Research Foundation and the Mito Foundation for research on mitochondrial and other rare diseases. He is a founding Director of the Mito Foundation and a former Chair of its Scientific & Medical Advisory Panel. He was a member of the NHMRC Expert Working Committee on Mitochondrial Donation and engaged with the reviews referred to in this article.</span></em></p><p class="fine-print"><em><span>Megan Munsie receives funding from ARC, MRFF, the Novo Nordisk Foundation. She is the Vice President of the Australasian Society for Stem Cell Research, non-executive director of the National Stem Cell Foundation of Australia and a member of ethics and policy advisory committees for several national and international organisations including the International Society for Stem Cell Research (ISSCR). She co-authored recently published ISSCR Guidelines that support clinical research for mitochondrial donation.</span></em></p>Parents at risk of passing on genetic disease to their children via mutations in the mother’s mitochondrial DNA could soon use a new IVF-based treatment involving healthy donor mitochondria.David Thorburn, co-Group Leader, Brain & Mitochondrial Research, Murdoch Children's Research InstituteMegan Munsie, Professor Emerging Technologies (Stem Cells), The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1462542020-10-22T12:24:25Z2020-10-22T12:24:25ZDisputes over when life begins may block cutting-edge reproductive technologies like mitochondrial replacement therapies<figure><img src="https://images.theconversation.com/files/363766/original/file-20201015-17-tcjd72.jpg?ixlib=rb-1.1.0&rect=275%2C66%2C5207%2C3234&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A computer illustration of a cross-section of a mitochondrion and its internal structure with DNA (gray), ribosomes (light green), granules (yellow) and ATP synthase particles (light blue).</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/internal-structure-of-a-mitochondrion-3d-royalty-free-illustration/1249064176?adppopup=true">TUMEGGY/SCIENCE PHOTO LIBRARY/Getty Images</a></span></figcaption></figure><p>The nomination of Judge Amy Coney Barrett to the U.S. Supreme Court has once again pushed the debate over when life begins into the headlines, which could have far-reaching effects on access to both current and emerging reproductive technologies. In 2006, Judge Barrett was <a href="https://www.theguardian.com/us-news/2020/oct/01/amy-coney-barrett-supported-group-fertilization">one of the signatories</a> on a newspaper ad sponsored by an anti-abortion group that not only believes life begins at fertilization but also hopes to criminalize discarding extra embryos created during in vitro fertilization.</p>
<p>As legal scholars, <a href="https://scholar.google.com/citations?user=WNsa-isAAAAJ&hl=en">we</a> <a href="https://isearch.asu.edu/profile/2712805">are</a> closely watching how jurisdictions regulate emerging reproductive technologies, including a set of techniques called mitochrondial replacement therapies which can prevent some heritable diseases. But because they use IVF methods, and some (but not all) of the techniques <a href="https://doi.org/10.1007/s11019-017-9772-3">require discarding an embryo</a>, law codifying the belief that life starts at fertilization could restrict access to mitochondrial replacement therapies and derail productive conversations about how to regulate them properly.</p>
<h2>Implications for assisted reproduction</h2>
<p>Last week, the medical journal <a href="https://els-jbs-prod-cdn.jbs.elsevierhealth.com/pb/assets/raw/Health%20Advance/journals/fns/oyez.pdf">Fertility & Sterility ran an editorial</a> arguing that confirming Judge Barrett could result in restrictions not only on reproductive rights to contraception and abortion, but also on IVF. One <a href="https://abovethelaw.com/2020/10/is-amy-coney-barrett-the-beginning-of-the-end-for-ivf/">concern</a> is that future legal decisions could forbid IVF clinics from discarding extra embryos – even ones unlikely to start a pregnancy – or limit the number of embryos which can be formed. That could raise treatment costs or make efforts to start a healthy pregnancy with IVF <a href="https://www.statnews.com/2018/07/24/are-embryos-people-the-answer-will-determine-the-future-of-reproductive-medicine/">much harder</a>. </p>
<p>The nomination of Judge Barrett also comes just as new technologies look almost ready to help parents have children free of certain heritable diseases. Children can inherit mitochondrial diseases from their <a href="https://www.nytimes.com/2016/06/24/science/mitochondrial-dna-mothers.html">biological mother</a> (and <a href="https://doi.org/10.1073/pnas.1810946115">possibly their father</a>) caused by dysfunctional mitochondria – which generate energy molecules for the cell. These tiny structures in the cell carry their own special DNA; but those that carry mutations can cause disease. A new type of reproductive technology called mitochondrial replacement therapies offers the possibility of preventing children from inheriting these diseases. </p>
<h2>Mitochondrial replacement therapies</h2>
<p>Estimates suggest <a href="https://my.clevelandclinic.org/health/diseases/15612-mitochondrial-diseases">1,000-4,000 children</a> in the U.S. alone are born each year with a heritable mitochondrial disease.</p>
<p>These complex diseases can affect <a href="https://www.cdc.gov/ncbddd/autism/mitochondrial-faq.html">many different organs</a> – especially those with high energy needs like the brain, eyes or heart. There are no cures and few treatment options exist, so children often die in severe cases. Having a child with mitochondrial diseases can place huge emotional and financial tolls on families, with significant economic costs for <a href="https://www.legislation.gov.uk/ukia/2015/138/pdfs/ukia_20150138_en.pdf">health care systems</a>.</p>
<p>With limited treatment options, some experts place more hope in preventing children from inheriting mitochondrial diseases altogether. Sometimes called “<a href="https://theconversation.com/how-can-a-baby-have-3-parents-97991">three parent IVF</a>,” <a href="https://www.hfea.gov.uk/treatments/embryo-testing-and-treatments-for-disease/mitochondrial-donation-treatment/">mitochondrial replacement therapies</a> make this possible by replacing the unhealthy mitochondria in an egg cell or embryo with healthy ones from a donor woman. Using this technique, couples at high risk of having children with mitochondrial diseases can then have a healthy child who is biologically related to them.</p>
<p>Mitochondrial replacement therapies do, however, raise a few concerns. Health problems could arise from <a href="https://doi.org/10.1038/nrm.2018.3">molecular mismatches</a> between the parents’ nucleus and donor mitochondria or from a treated embryo <a href="https://doi.org/10.1016/j.stem.2016.04.001">reverting</a> to an unhealthy state, though these risks are hypothetical for now. And female children born through mitochondrial replacement therapies could, theoretically, pass these conditions to their children.</p>
<p>Because mitochondria carry 37 of their own genes, children born from mitochondrial replacement therapies technically have DNA from three people – the couple and the woman who donated her healthy mitochondria. The donor contributes a <a href="https://theconversation.com/3-parent-ivf-could-prevent-illness-in-many-children-but-its-really-more-like-2-002-parent-ivf-126591">minuscule amount</a> of DNA – less than 1% – but this does raise questions about their “parenthood.” Another concern is that swapping out mitochondria (and their DNA) in embryos makes for a slippery slope to designer babies, especially now that <a href="https://www.sciencemag.org/news/2019/12/chinese-scientist-who-produced-genetically-altered-babies-sentenced-3-years-jail">three births</a> have occurred after gene editing.</p>
<h2>Regulating mitochondrial replacement therapies</h2>
<p>These safety and ethical concerns call for policy to investigate and minimize risks, while answering questions like what the legal status of the third “parent” should be.</p>
<p>In 2015, the United Kingdom became the first jurisdiction in the world to expressly <a href="https://www.legislation.gov.uk/ukdsi/2015/9780111125816/contents">legalize and regulate</a> mitochondrial replacement therapies, creating a system to license clinics for this service. This move came after an extensive <a href="https://www.hfea.gov.uk/media/2618/mitochondria_replacement_consultation_-_advice_for_government.pdf">public engagement</a> process. Regulation is overseen by the Human Fertilisation and Embryology Authority, which governs all human fertility treatments and research within the U.K. Two other countries, Australia and Singapore, are considering legislative amendments to follow in the U.K.’s footsteps.</p>
<p>While brand-new regulatory systems for mitochondrial replacement therapies may seem ideal, <a href="https://doi.org/10.1017/S1867299X00002105">lessons learned</a> from other emerging technologies suggest most countries probably won’t adopt this approach – since existing rules often apply already, though maybe not in an ideal way. The trick then becomes making sure existing rules can still cover concerns with the new technology. However, this reality has led to critics raising the alarm about “unregulated” mitochondrial replacement therapies, especially since medical tourism is <a href="https://theconversation.com/the-next-frontier-in-reproductive-tourism-genetic-modification-67132">already happening</a>.</p>
<p>Even if most countries don’t enact new laws, many already have rules which should apply to mitochondrial replacement therapies. For example, the U.S. won’t need a new regulatory system if it removes its current <a href="https://www.statnews.com/2019/04/16/mitochondrial-replacement-three-parent-ivf-ban/">ban</a> on the technology. The Food and Drug Administration <a href="https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/therapeutic-cloning-and-genome-modification">already plans</a> on regulating mitochondrial replacement therapies with the same tools it uses for “biologics,” a broad category of medical products ranging from vaccines to gene therapy.</p>
<p>Mexico got a bad reputation for having “no rules” after a child was born there via mitochondrial replacement therapies, but <a href="https://doi.org/10.1093/jlb/lsw065">legal scholars</a> have pointed out that Mexico’s regulations on health research likely prohibit this use of mitochondrial replacement therapies. However, these rules weren’t triggered because doctors modified the embryos in the U.S., before sending them to Guadalajara for the treatment. Instead, the <a href="https://www.fda.gov/media/106739/download">U.S. FDA intervened</a>, informing the clinic that they had violated U.S. law in several ways.</p>
<p>In Greece, regulators already approved a <a href="http://www.isrctn.com/ISRCTN11455145">clinical trial</a> for mitochondrial replacement therapies using their existing rules for fertility treatments – although the trial addresses the success of fertility treatments instead of preventing mitochondrial diseases. And in Ukraine, though the details are murky, health officials appear to have similarly approved a <a href="https://www.npr.org/sections/health-shots/2018/06/06/615909572/inside-the-ukrainian-clinic-making-3-parent-babies-for-women-who-are-infertile">clinical trial</a> for mitochondrial replacement therapies.</p>
<h2>Moving forward</h2>
<p>Reproductive technologies have allowed <a href="https://www.cnn.com/2018/07/03/health/worldwide-ivf-babies-born-study/index.html">millions of families</a> around the world to conceive healthy children over the last 42 years. For the first time, recent advances in mitochondrial replacement therapies could allow families who otherwise couldn’t have a healthy child of their own to do so. But changes in law that restrict access to IVF could have profound social and medical impacts that would ripple across the country. </p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>Rather than making reproductive technologies like mitochondrial replacement therapies more difficult to access – especially for those with a medical reason for doing so – we believe regulators and governments should be looking for ways to provide individuals access to these technologies in a way that promotes safety and efficacy for everyone involved. That includes those living in the U.S. who wish to access mitochondrial replacement therapies in their own country.</p><img src="https://counter.theconversation.com/content/146254/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Diana Bowman receives funding from the Andrew Carnegie Fellows Program. </span></em></p><p class="fine-print"><em><span>Walter G. Johnson does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The nomination of Judge Amy Coney Barrett has implications for how assisted reproductive technologies, which can prevent the transmission of disease from parents to child, are regulated.Walter G. Johnson, Research Fellow, Arizona State UniversityDiana Bowman, Associate Dean for International Engagement in the College of Law, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1261302019-10-31T11:59:02Z2019-10-31T11:59:02ZBotswana is humanity’s ancestral home, claims major study – well, actually …<figure><img src="https://images.theconversation.com/files/299660/original/file-20191031-187934-1yecnej.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A study claims the first humans lived in a wetland around what is now northern Botswana.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aerial-view-okavango-delta-botswana-africa-381563779?src=c26RxRWx6zN_fvWLLN7FIw-1-0">Prill/Shutterstock</a></span></figcaption></figure><p>A recent paper in the prestigious <a href="https://www.nature.com/articles/s41586-019-1714-1">journal Nature</a> claims to show that modern humans originated about 200,000 years ago in the region <a href="http://theconversation.com/humanitys-birthplace-why-everyone-alive-today-can-call-northern-botswana-home-125814">around northern Botswana</a>. For a scientist like myself who studies human origins, this is exciting news. If correct, this paper would suggest that we finally know where our species comes from.</p>
<p>But there are actually several reasons why I and <a href="https://www.sciencemag.org/news/2019/10/experts-question-study-claiming-pinpoint-birthplace-all-humans">some of my colleagues</a> are not entirely convinced. In fact, there’s good reason to believe that our species doesn’t even have a single origin.</p>
<p>The scientists behind the new research studied genetic data from many individuals from the KhoeSan peoples of southern Africa, who are thought to live where their ancestors have lived for hundreds of thousands of years. The researchers used their new data together with existing information about people all around the world (including other areas traditionally associated with the origins of humankind) to reconstruct in detail the branching of the human family tree.</p>
<p>We can think of the earliest group of humans as the base of the tree with a specific set of genetic data - a gene pool. Each different sub-group that branched off and migrated away from humanity’s original “homeland” took a subset of the genes in that gene pool with them. But most people, and so the vast majority of those genes, remained behind. This means people alive today with different subsets of our species’ genes can be grouped on different branches of the human family tree.</p>
<p>Groups of people with the most diverse genomes are likely to be the ones that descended directly from the original group at the base of the tree, rather than one of the small sub-groups that split from it. In this case, the researchers identified one of the groups of KhoeSan people from around northern Botswana as the very bottom of the trunk, using geographical and archaeological data to back up their conclusion. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/299662/original/file-20191031-30397-qkcywn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/299662/original/file-20191031-30397-qkcywn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/299662/original/file-20191031-30397-qkcywn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/299662/original/file-20191031-30397-qkcywn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/299662/original/file-20191031-30397-qkcywn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/299662/original/file-20191031-30397-qkcywn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/299662/original/file-20191031-30397-qkcywn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lead study author Vanessa Hayes with Juǀ’hoansi hunters in Namibia.</span>
<span class="attribution"><span class="source">Chris Bennett, Evolving Picture</span></span>
</figcaption>
</figure>
<p>If you compare this process to creating your own family tree, it makes sense to think you can use information about who lives where today and how everyone relates to each other to reconstruct where the family came from. For example, many of my relatives live on the lovely Channel Island of Alderney, and one branch of my family have indeed been islanders for many generations.</p>
<p>Of course, there’s always some uncertainty created by variations in the data. (I now live in Wales and have cousins in England.) But as long as you look for broad patterns rather than focusing on specific details, you will still get a reasonable impression. There are even some statistical techniques you can use to assess the strength of your interpretation.</p>
<p>But there are several problems with taking the process of building a human family tree to such a detailed conclusion, as this new research does. First, it’s important to note that the study didn’t look at the whole genome. It focused just on <a href="https://www.nature.com/scitable/topicpage/mtdna-and-mitochondrial-diseases-903/">mitochondrial DNA</a>, a small part of our genetic material that (unlike the rest) is <a href="https://theconversation.com/study-shows-mitochondrial-dna-can-be-passed-through-fathers-what-does-this-mean-for-genetics-107641">almost only ever</a> passed from <a href="https://www.nytimes.com/2016/06/24/science/mitochondrial-dna-mothers.html">mothers to children</a>. This means it isn’t mixed up with DNA from fathers and so is easier to track across the generations. </p>
<p>As a result, mitochondrial DNA is commonly used to reconstruct evolutionary histories. But it only tells us part of the story. The new study doesn’t tell us the origin of the human genome but the place and time where our mitochondrial DNA appeared. As a string of just 16,569 genetic letters out of over 3.3 billion in each of our cells, mitochondrial DNA is a very tiny part of us.</p>
<h2>Other DNA</h2>
<p>The fact that mitochondrial DNA comes almost only ever from mothers also means the story of its inheritance is much simpler than the histories of other genes. This implies that every bit of our genetic material may have a different origin, and have followed a different path to get to us. If we did the same reconstruction <a href="https://www.newscientist.com/article/dn23240-the-father-of-all-men-is-340000-years-old/">using Y chromosomes</a> (passed only from <a href="https://genetics.thetech.org/ask/ask295">father to son</a>) or whole genomes, we’d get a different answer to our question about where and when humans originated.</p>
<p>There is actually <a href="https://www.nature.com/news/genetic-adam-and-eve-did-not-live-too-far-apart-in-time-1.13478">a debate</a> over whether the woman from whom all our mitochondrial DNA today descends (“mitochondrial Eve”) could ever have even met the man from whom all living men’s Y-chromosomes descend (“Y-chromosome Adam”). By some estimates, they may have lived as much as 100,000 years apart. </p>
<p>And all of this ignores the possibility that other species or populations may also have contributed DNA to modern humans. After this mitochondrial “origin”, our species interbred <a href="https://www.livescience.com/64189-neanderthals-and-humans-interbreeding.html">with Neanderthals</a> and a group called <a href="https://phys.org/news/2019-04-evidence-denisovans-interbreeding-humans-southeast.html">the Denisovans</a>. There’s even evidence that these two interbred with one another, at about the same time as they were <a href="https://www.nature.com/articles/d41586-018-06004-0">hybridising with us</a>. Earlier modern humans probably also interbred with other human species living alongside them in other time periods.</p>
<p>All of this, of course, suggests that modern human history – like the history of <a href="https://www.tandfonline.com/doi/abs/10.3109/03014460.2014.922613">modern primates</a> – was much more than a simple tree with straight lines of inheritance. It’s much more likely that our distant ancestors interbred with other species and populations to form a braiding stream of gene pools than that we form a nice neat tree that can be reconstructed genetically. And if that’s true, we may not even have a single origin we can hope to reconstruct.</p><img src="https://counter.theconversation.com/content/126130/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Isabelle Catherine Winder received funding from the European Research Council (ERC) as part of the DISPERSE project (2011-2016). It was as part of her work as a post-doc on this project that she wrote the paper about reticulation and the human past cited in this article.</span></em></p>It’s likely our species doesn’t actually have a single origin.Isabelle Catherine Winder, Lecturer in Zoology, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1258142019-10-28T19:06:33Z2019-10-28T19:06:33ZHumanity’s birthplace: why everyone alive today can call northern Botswana home<figure><img src="https://images.theconversation.com/files/298877/original/file-20191028-113980-qj9kj9.jpeg?ixlib=rb-1.1.0&rect=4%2C25%2C894%2C573&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researcher Vanessa Hayes with the Ju/’hoansi people in the ancestral homeland of humanity.</span> <span class="attribution"><span class="source">Chris Bennett/Evolving Picture</span></span></figcaption></figure><p>Where was the evolutionary birthplace of modern humans? The East African Great Rift Valley has long been the favoured contender – until today. </p>
<p>Our new research has used DNA to trace humanity’s earliest footsteps to a prehistoric wetland called Makgadikgadi-Okavango, south of the Great Zambezi River.</p>
<p>Our analysis, <a href="https://doi.org/10.1038/s41586-019-1714-1">published in Nature today</a>, shows that the earliest population of modern humans (<em>Homo sapiens sapiens</em>) arose 200,000 years ago in an area that covers parts of modern-day Botswana, Namibia and Zimbabwe. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=335&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=335&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=335&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=421&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=421&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298878/original/file-20191028-113953-1lj35xj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=421&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The left map shows the distribution of ancestral DNA among the sampled population. This allowed the ancestral homeland to be pinpointed to a region (shown on the right in pale orange) south of the Zambezi River, centred on northern Botswana.</span>
<span class="attribution"><span class="source">Chan et al., Nature 2019</span></span>
</figcaption>
</figure>
<p>Today it is a dry and dusty land with scattered salt pans, and it is hard to believe that modern humans lived and thrived in wetlands here for 70,000 years before our ancestors began to explore the rest of Africa, and ultimately the world.</p>
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<strong>
Read more:
<a href="https://theconversation.com/ancestors-a-new-game-provides-insights-into-how-the-first-humans-evolved-123318">'Ancestors': a new game provides insights into how the first humans evolved</a>
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<p>We pinpointed this region by studying mitochondrial DNA, known as the “mitogenome”. Unlike nuclear DNA, which is passed on by both mother and father, mitochondrial DNA is passed on only by the mother, which means it is not jumbled up in each generation.</p>
<p>If we think of all modern humans as occupying a particular place on a huge family tree, logically we should find the most diverse mitogenomes at the very base of the tree, because it is the ultimate source of all the various branches.</p>
<p>We already know that genetic data points to southern Africa as the cradle of humanity (unlike fossil evidence, most of which has been found in East Africa). But we wanted to refine our search still further, to pinpoint the exact location where humans first evolved.</p>
<p>To do this, we turned our attention to a group of people known as the KhoeSan. KhoeSan have the most diverse mitogenomes of anyone on Earth, which suggests their DNA most closely resembles that of our shared common ancestors. If we all sit on branches of the human family tree, then KhoeSan are the tree’s trunk.</p>
<p>Linguistically, KhoeSan people are click speakers, while culturally KhoeSan are foragers, with groups of San people still practising the old ways of life – hunting and gathering for subsistence.</p>
<p>Members of our research team have spent a decade working with KhoeSan communities, as well as people from other ethnicities and language groups, in Namibia and South Africa.</p>
<p>By generating mitogenome data for around 200 rare or newly discoverd sub-branches of KhoeSan lineages, and merging them with all available data, we were able to zoom in on the very base of our evolutionary tree.</p>
<p>It is now clear our ancestors must have dispersed from a region south of the Zambezi River. This is consistent with geographical, archaeological and climate data, including the fact that this area would have been a fertile wetland at the time the first modern humans emerged.</p>
<h2>Lush landscapes</h2>
<p>Geological evidence suggests that at this time, the prehistoric Makgadikgadi lake that had dominated the region for millions of years had begun to break up through the shifting of the land. This would have created a vast wetland region, ideal to sustain life. </p>
<p>But if it was so ideal, why did our ancestors begin to explore other places between 130,000 and 110,000 years ago, first heading northeast and later southwest from the ancestral home? </p>
<p>Climate data suggests that at around that time the region experienced a huge drought. Notably, about 130,000 years ago humidity increased to the northeast of the homeland, and 110,000 years ago the same happened to the southwest. We speculate that this created passages of lush vegetation for our ancestors to leave the homeland, most likely following the game animals that were also forging into new regions.</p>
<p>What’s more, our genetic data suggests the southerly migrants went on to inhabit the entire southern coast of Africa, with multiple sub-populations and huge population growth. Archaeological findings from the Blombos caves in South Africa have shown this region to be rich in evidence for cognitive human behaviour as early as 100,000 years ago. Again, we were amazed at how well we could match timeline data, crossing different yet complimentary disciplines that have historically not worked together. This also allowed us to further speculate about the success of the southerly migrants being attributed to adapting their skills to the abundance of life in the oceans.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-dna-is-a-powerful-tool-for-studying-the-past-when-archaeologists-and-geneticists-work-together-111127">Ancient DNA is a powerful tool for studying the past – when archaeologists and geneticists work together</a>
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<p>These earliest explorers left behind a homeland population, one that still remains within the ancestral lands today, having adapted to the much drier landscape. It has been a pleasure to spend the past decade engaging with the last descendants of humanity’s homeland, including the Ju/’hoansi people of the Kalahari in Namibia. </p>
<p>The Ju/’hoansi, who still practise their traditional way of life, are excited about our findings. They believe our study captures a history that they have told for generations by word of mouth alone. This is not only their story, but all of ours.</p><img src="https://counter.theconversation.com/content/125814/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vanessa Hayes receives funding from Australian Research Council Discovery Project grant (DP170103071) and holds the Sydney University Petre Chair of Prostate Cancer Research. She is affiliated with the University of New South Wales Sydney, as well as the University of Pretoria and University of Limpopo in South Africa. </span></em></p>Genetic analysis has traced the evolutionary footsteps of modern humans all the way back to a prehistoric wetland that spanned parts of modern-day Botswana, Namibia and Zimbabwe.Vanessa Hayes, Professor, Garvan Institute of Medical Research and, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1235042019-09-25T12:12:37Z2019-09-25T12:12:37ZSneaky lions in Zambia are moving across areas thought uninhabitable for them<figure><img src="https://images.theconversation.com/files/293046/original/file-20190918-187980-1ekemtt.jpg?ixlib=rb-1.1.0&rect=117%2C64%2C1151%2C824&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Where has this Zambian lion been?</span> <span class="attribution"><span class="source">Paula White</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Zambia, a country in southeast Africa, has approximately <a href="http://www.africanliongroup.org/uploads/5/0/0/7/5007626/session_minutes_final.pdf">1,200 lions</a>, one of the largest lion populations on the continent. More than 40% of the U-shaped country is <a href="http://doi.org/10.1371/journal.pone.0094109">protected land</a>, with over 120,000 square miles of national parks, sanctuaries and game management areas for lions to roam.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=519&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=519&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=519&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=652&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=652&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293818/original/file-20190924-51463-5pwiyp.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=652&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Zambia’s lion populations benefit from lots of protected lands.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1371/journal.pone.0217179">Curry et al., PLOS ONE 2019</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Zambian lions are split into two subpopulations, with one in the Greater Kafue Ecosystem in the west and the other in the Luangwa Valley Ecosystem in the east. Between these two geographically different regions lies Lusaka, Zambia’s largest city, which is surrounded by farmland.</p>
<p>People had assumed that the two groups of lions <a href="https://doi.org/10.1007/s10531-012-0381-4">did not – even could not – mix</a>. After all, they’re separated by a geographical barrier: the two regions feature different habitats, with the east an offshoot of the Great Rift Valley system and the west part of the southern savannas. The lions are also separated by what’s called an <a href="https://allafrica.com/stories/201308110044.html">anthropogenic barrier</a>: a big city that lacks wildlife protection, making it seemingly unsuitable for lions.</p>
<p><a href="https://scholar.google.com/citations?user=a_TzvI0AAAAJ&hl=en&oi=ao">So my</a> <a href="https://www.researchgate.net/profile/Paula_White4">colleagues</a> <a href="https://scholar.google.com/citations?user=vAkgkSsAAAAJ&hl=en&oi=ao">and I</a> were surprised when we found that a small number of lions are in fact <a href="https://doi.org/10.1371/journal.pone.0217179">moving across the area</a> in between presumed to be uninhabitable by lions. These sneaky lions – and their mating habits – are causing the high levels of genetic diversity we found in the entire Zambian lion population.</p>
<h2>Identifying which genes are where</h2>
<p>Working with the Zambian Wildlife Authority, <a href="http://safariclubfoundation.org/zambia-lion-project/">biologist Paula White</a> collected hundreds of biological samples from lions across Zambia between 2004 and 2012. Eventually a box of this hair, skin, bone and tissue, meticulously packaged and labeled with collection notes and sampling locations, arrived at my lab at Texas A&M University.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293826/original/file-20190924-51463-1693ods.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Unwrapping African samples in a Texas lab.</span>
<span class="attribution"><span class="source">Caitlin J. Curry</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our goal was to investigate genetic diversity and the movement of various genes across Zambia by extracting and analyzing DNA from the lion samples.</p>
<p>From 409 lions found inside and outside of protected lands, I looked at two kinds of genes, mitochondrial and nuclear. You inherit mitochondrial DNA only from your mom, while you inherit nuclear DNA from both of your parents. Because of these differences, mitochondrial and nuclear genes can tell different genetic stories that, when combined, paint a more complete picture of how a population behaves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293828/original/file-20190924-51410-1jwh2lh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Both nuclear (left) and mitochondrial (right) analyses show two genetically distinct Zambian lion subpopulations.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/f5CFy6-FaC4">Photo by Wade Lambert, diagram by Caitlin J. Curry</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>My mitochondrial analysis verified that, genetically, there are <a href="https://doi.org/10.1371/journal.pone.0143827">two isolated subpopulations of lions</a> in Zambia, one in the east and one in the west. However, by also looking at the nuclear genes, we found evidence that small numbers of lions are moving across the “unsuitable” habitat. Including nuclear genes provided a more complex picture that tells us not only which lions were moving but also where.</p>
<h2>Genes on the move as lions roam</h2>
<p>The amount of variation from alternate forms of genes found within a population is known as genetic diversity. Genetic diversity is important for a wildlife population because more genetic options give animals a greater chance for adaptation in a changing environment. Genetic diversity can also tell biologists about ways a population can fluctuate.</p>
<p>To a geneticist, migration, also referred to as <a href="https://evolution.berkeley.edu/evolibrary/article/evo_21">gene flow</a>, is the movement of genes from one geographical place to another. Mitochondrial DNA, inherited from the mother, can only tell researchers where genes from mom have been.</p>
<p>In the lion mating system, males travel long distances to find new prides, while females remain in or close to the pride they were born in. So, for the lion, it’s primarily males that are responsible for the movement of genes between prides. This male-mediated gene flow explains the lack of gene flow seen in mitochondrial genes compared to that of nuclear genes – female lions aren’t making the journey, but they do mate with new males who come from far away.</p>
<p>Male-mediated gene flow has helped keep the lions of Zambia genetically healthy, increasing genetic diversity by introducing new genes to new areas as male lions move between subpopulations. The eastern and western subpopulations each have high levels of genetic diversity; since only a few lions move between the groups each generation, the subpopulations stay genetically distinct.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293829/original/file-20190924-51434-1bwagis.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=460&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How genetically similar are individual lions? Represented by dots, individuals clustered together share more genes than those far apart. Lion dots are colored based on which national park they were found in.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1371/journal.pone.0217179">Curry et al, PLOS ONE, 2019</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>My colleagues and I were also able to determine where the lions are moving based on which individuals are more <a href="https://en.wikipedia.org/wiki/Isolation_by_distance">genetically similar to each other</a>. Lions in the North and South Luangwa National Parks, part of the eastern subpopulation, appear completely separated from the western subpopulation. Gene flow is occurring through the southern regions of the eastern subpopulation.</p>
<p>Lions are most likely traveling a route between the Lower Zambezi National Park and eastern corridor to the Kafue National Park in the west, possibly along the Kafue River. We can’t tell which way they’re moving, but by looking at where lions are more closely related, we can see where genes are being moved.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=453&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=453&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=453&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293833/original/file-20190924-51463-q5av8i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It’s male lions that travel to find new prides.</span>
<span class="attribution"><span class="source">Paula White</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Lion data can help manage wildlife overall</h2>
<p>Human-lion conflict is a big issue in Zambia, <a href="https://www.cms.int/sites/default/files/document/ac27_cites_periodic_rev_status_african_lion_across_range_e.pdf">particularly outside of protected land</a>. If lions were moving across human dominated areas, you’d think they’d be seen and reported. But these lions are sneaking through virtually undetected – until we look at their genes. </p>
<p>As a large, charismatic carnivore, lion research and conservation influences many other species that share their habitat.</p>
<p>Wildlife managers can use these findings to help with lion conservation and other wildlife management in and around Zambia. Now that we generally know where lions are moving, managers can focus on these areas to find the actual route the big cats are taking and work to maintain or even increase how many lions can move across these areas. One of the ways of doing this is by creating more protected land, like corridors, to better connect suitable habitat.</p>
<p>[ <em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/123504/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This project received funding from Zambia Wildlife Authority, Professional Hunters Association of Zambia, Safari Hunters and Outfitters Association of Zambia, the Boore Family Foundation, Dallas Safari Club, Safari Club International Foundation and the Texas A&M Foundation. </span></em></p>Male lions are responsible for the movement of genes between prides. New research confirmed that the genes are traveling long distances – even though no one has been spotting the lions on the journey.Caitlin J. Curry, Phd Student in absentia of Veterinary Pathobiology, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1183922019-06-12T11:32:15Z2019-06-12T11:32:15ZWhat the ban on gene-edited babies means for family planning<figure><img src="https://images.theconversation.com/files/278519/original/file-20190607-52739-l05xdd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When it comes to reproduction, couple have more choices than ever before.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/patient-couple-consulting-doctor-psychologist-on-1193897125">Chinnapong/Shutterstock.com</a></span></figcaption></figure><p>Technology surrounding the human embryo has moved out of the realm of science fiction and into the reality of difficult decisions. Clinical embryologists fertilize human eggs for the purpose of helping couples conceive. The genetic makeup of these embryos are tested on a routine basis. And today, we no longer ask “can we,” but rather, “should we” edit human embryos with the goal of implantation and delivery of a baby?</p>
<p>As a reproductive endocrinologist, I frequently encounter couples grappling with complicated reproductive issues. If one or both parents are affected by single gene disorders, these couples have the opportunity to first test their embryos and then decide whether to transfer an embryo carrying a mutation rather than finding out the genetic risk of their baby while pregnant. In some cases they may decide not to transfer an embryo that carries the mutation as part of the in vitro fertilization procedure. </p>
<p>These issues seem simple, but carry large consequences for patients. “Should we transfer an embryo affected with our genetic disorder?” “What should we do with our affected embryos if we do not transfer them?” Some patients will opt to skip testing altogether. </p>
<h2>Clinical trials of GM embryos banned in the US</h2>
<p>House Democrats this year considered, then backed away from, lifting a ban written into the budget of the U.S. Food and Drug Administration that bars the approval of any clinical trial or research “in which a <a href="https://www.sciencemag.org/news/2019/06/update-house-spending-panel-restores-us-ban-gene-edited-babies">human embryo is intentionally created or modified</a> to include a heritable genetic modification.” The current gene-editing ban prohibits editing the genes inside the cell’s nucleus, as Chinese scientist He Jiankui did. He used the gene-editing tool CRISPR to <a href="https://theconversation.com/how-a-scientist-says-he-made-a-gene-edited-baby-and-what-health-worries-may-ensue-107764">modify the CCR5 gene in twin girls</a> to give them immunity from HIV. </p>
<p>The current ban also prohibits so-called mitochondrial replacement therapy, or <a href="https://theconversation.com/how-can-a-baby-have-3-parents-97991">three-parent babies</a>. </p>
<p>Mitochondria replacement therapy, in which mitochondria carrying defective genes are replaced by healthy mitochondria from a third party <a href="https://annualmeeting.acog.org/news/many-concerns-surround-mitochondrial-transfer/">is more palatable to some</a> as mitochondrial DNA only carries a handful of genes that provide cellular energy production. </p>
<p>These scenarios of a <a href="https://theconversation.com/how-can-a-baby-have-3-parents-97991">three-parent baby</a> involve transfer of the nucleus - containing the 23 chromosomes - from the egg of the mother with the defective mitochondria into an egg from which the nucleus has been removed but the healthy mitochondria remain. The actual genetic material is changed because there is DNA from two women. However, the DNA has not been cut, pasted or otherwise modified. Although testing the safety of three-parent babies will be allowed in some countries such as the United Kingdom, the U.S. ban includes this procedure. </p>
<h2>What is germline editing?</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=597&fit=crop&dpr=1 600w, https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=597&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=597&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=751&fit=crop&dpr=1 754w, https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=751&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/278558/original/file-20190607-52739-1emrruf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=751&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The 23 pairs of chromosomes, which are made from DNA, are stored in the nucleus of the cell. The mitochondria produce the energy for the cell and have their own DNA.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/structure-human-cells-organelles-core-nucleus-553881673?src=V9eJQZhCqeVykM3dWjPxQQ-1-37">Timonina/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>At the heart of the issue is making genetic changes to cells that could be passed on to the next generation. These are called germline cells, and changing them is called germline editing. This brings these questions to the next level, with little information to support these heartwrenching choices. </p>
<p>Germline editing can happen at different phases of fertilization. If we change the genetic makeup of a human egg or sperm, fertilize it, and transfer the resulting embryo into the womb, the result is a heritable genetic modification. Similarly, genetic changes to the embryo itself within the first few days after fertilization will be inherited by the embryo’s offspring. Both of these actions are currently banned.</p>
<h2>Is there any DNA that is OK to edit?</h2>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/278946/original/file-20190611-32351-imijs0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/278946/original/file-20190611-32351-imijs0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/278946/original/file-20190611-32351-imijs0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/278946/original/file-20190611-32351-imijs0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/278946/original/file-20190611-32351-imijs0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/278946/original/file-20190611-32351-imijs0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/278946/original/file-20190611-32351-imijs0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sometimes the DNA inside the mitochondria carry mutations that cause disease. In mitochondria replacement therapy, the unhealthy mitochondria are replaced with those from a third party, or ‘parent.’</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/education-chart-biology-mitochondria-diagram-vector-1057812953?src=UHmWJcbvLQ-2FRN73FWNEQ-1-46">Vecton/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Our genetic material is made up of DNA. This DNA is found in two locations within our cells – the nucleus and mitochondria. The DNA, which makes up our 23 pairs of chromosomes, is found inside the nucleus of every cell is a combination of the DNA from the biological mother’s egg and biological father’s sperm. Genes composed from this nuclear DNA provide the basis of most of our biologic functions and appearance including our height, eye color and our overall predisposition to diseases such as diabetes, heart disease and cancer. These traits are often the <a href="https://ghr.nlm.nih.gov/primer/basics/gene">product of multiple genes</a> working in tandem. The products of these genes work together throughout our lives, which makes the impact of editing at the embryonic level impossible to predict. </p>
<p>He Jiankui performed gene editing on nuclear DNA. This action provoked calls for <a href="https://www.asrm.org/news-and-publications/news-and-research/press-releases-and-bulletins/asrm-statement-on-reports-of-human-reproductive-gene-editing-in-china/">regulatory oversight of gene-editing techniques</a>. The concern lies in the long-term effects. In addition to their constant interaction, most of genes in the cell’s nucleus serve multiple functions. “Fixing” one aspect of a gene’s function may therefore result in <a href="https://www.bbc.com/news/health-48496652">unintended consequences</a>. </p>
<p>Those diseases <a href="https://www.ncbi.nlm.nih.gov/books/NBK132154/">caused by a single gene mutation</a> in nuclear DNA are more obvious candidates for gene editing because they are more likely to result in a cure. These include cystic fibrosis, muscular dystrophy and sickle cell anemia. </p>
<h2>Are three-parent babies different?</h2>
<p>Mitochondrial DNA is located outside the cell’s nucleus and passed down directly from the female egg to the embryo. Genes composed of mitochondria DNA enable mitochondria to produce energy for the whole cell. <a href="https://ghr.nlm.nih.gov/mitochondrial-dna">Mutations in mitochondrial genes</a> have been associated with <a href="http://doi.org/10.1038/nrdp.2016.80">severe disorders</a> such as <a href="https://ghr.nlm.nih.gov/condition/leigh-syndrome">Leigh syndrome</a> and <a href="https://ghr.nlm.nih.gov/condition/mitochondrial-complex-iii-deficiency">mitochondrial complex III deficiency</a> that can affect the brain, kidney and heart.</p>
<p>Just as nuclear DNA modification may remove the risk for single gene disorders, mitochondria replacement therapy would replace these mutated mitochondrial genes with mitochondria from a donor egg – a change that will passed to future generations.</p>
<p>Throughout this discussion, I try to maintain a sense of empathy for those families for whom this could be their only hope of having a healthy biologically related child. I also try to convey that we are at the beginning of a long road that will require a thoughtful approach to anything we do. The technology is here, but we know so much less about its effects than we should. </p>
<p>These editing therapies will permanently change all the descendants of a couple. In some cases it could rid a family of a genetic disease. In others, the unintended effects may be worse than the disease itself. This is the purpose of ethically appropriate research with careful oversight. The ban does not change the need for discussion. If anything, it brings the debate back to the reality of patients seeking care for diseases that currently have no cure.</p>
<p>[ <em><a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=thanksforreading">Thanks for reading! We can send you The Conversation’s stories every day in an informative email. Sign up today.</a></em> ]</p><img src="https://counter.theconversation.com/content/118392/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marie Menke does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A ban on clinical trials involving gene editing rules out the controversial procedure done in China. But it also prevents procedures that could offer couples a chance for healthy children without genetic disorders.Marie Menke, Assistant Professor of Obstetrics, Gynecology & Reproductive Sciences, University of PittsburghLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1081682018-12-19T19:09:09Z2018-12-19T19:09:09ZDNA from ancient Aboriginal Australian remains enables their return to Country<figure><img src="https://images.theconversation.com/files/248598/original/file-20181204-23261-d9e96q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Indigenous Australians must be involved in research around provenance and country. Here, representatives of the Willandra Aboriginal Elders visit the Griffith University ancient DNA laboratory. </span> <span class="attribution"><span class="source">Renee Chapman </span>, <span class="license">Author provided</span></span></figcaption></figure><p><em>This article was coauthored by Gimuy Yidniji Traditional Owner Gudju Gudju Fourmile.</em></p>
<hr>
<p>For many decades Aboriginal Australians have campaigned for the return of ancestral remains that continue to be stored in museums worldwide. </p>
<p>But in many instances these remains cannot be repatriated – as their geographic origin, tribal affiliation or language group was never identified. Without this information it is impossible for museums to determine appropriate custodians, which prevents their return.</p>
<p>Our research, published in <a href="http://advances.sciencemag.org/content/4/12/eaau5064">Science Advances today</a>, shows it is possible to determine the origin of Aboriginal Australian remains using DNA-based methods, enabling their return to Country. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dna-reveals-a-new-history-of-the-first-australians-65344">DNA reveals a new history of the First Australians</a>
</strong>
</em>
</p>
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<h2>Collaborative beginnings</h2>
<p>Past injustices due to actions and policies implemented in <a href="https://theconversation.com/sorry-isnt-the-hardest-word-so-say-it-for-the-stolen-generations-7079">early colonial history</a> have left gaps in the self-knowledge of many contemporary Aboriginal Australians. </p>
<p>A key term in this context is “Country”: the place in which an Aboriginal Australian, or his or her ancestors, was born and lived. For some communities their Country encompasses large geographical areas; for others it is much smaller. </p>
<p>Aboriginal Australians believe they have a spiritual connection to their Country – and many believe that in order for their ancestor’s spirits to rest, their remains must be returned to Country.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/248597/original/file-20181204-23267-11ayhld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/248597/original/file-20181204-23267-11ayhld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/248597/original/file-20181204-23267-11ayhld.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/248597/original/file-20181204-23267-11ayhld.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/248597/original/file-20181204-23267-11ayhld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/248597/original/file-20181204-23267-11ayhld.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/248597/original/file-20181204-23267-11ayhld.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Lake Mungo World Heritage Site has a long history of Aboriginal occupation.</span>
<span class="attribution"><span class="source">Sherene Lambert (St Augustine's College, Ipswich, Australia)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Many of our traditional owner collaborative partners wanted to learn more about their history through DNA analyses – and to directly test whether DNA might help with the return of <a href="https://theconversation.com/the-violent-collectors-who-gathered-indigenous-artefacts-for-the-queensland-museum-96119">unprovenanced remains</a> from museums worldwide to Country.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-violent-collectors-who-gathered-indigenous-artefacts-for-the-queensland-museum-96119">The violent collectors who gathered Indigenous artefacts for the Queensland Museum</a>
</strong>
</em>
</p>
<hr>
<p>Our research, undertaken in collaboration with Aboriginal Australian traditional owners and communities across Australia, tested whether it is possible to determine the origins of ancient individuals using DNA-based methods. </p>
<p>We successfully recovered ten nuclear genomes (DNA from cell nuclei) and 27 mitogenomes (DNA from cell <a href="https://theconversation.com/explainer-what-are-mitochondria-and-how-did-we-come-to-have-them-83106">mitochondria</a>) from ancient pre-European Aboriginal Australians dating up to 1,540 years before present – and for whom we had records of Country. </p>
<p>These ancient genomic sequences, of known origin, were used as proxies for unprovenanced remains. We compared these against reference datasets of contemporary Aboriginal Australian nuclear and mitochondrial genomes. </p>
<p>Previously the only authentic pre-European DNA ever recovered from Aboriginal Australian remains was the mitochondrial genome of an <a href="https://theconversation.com/new-dna-study-confirms-ancient-aborigines-were-the-first-australians-60616#comment_1264911">ancient man from the Willandra Lakes region</a>. Here we show it is also possible to recover ancient nuclear genomes from Aboriginal Australian remains, despite DNA survival in an Australian context being poor due to harsh climatic conditions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=529&fit=crop&dpr=1 600w, https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=529&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=529&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=665&fit=crop&dpr=1 754w, https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=665&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/250907/original/file-20181217-185255-1nybssg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=665&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Details of the locations and language groups of Aboriginal Australian samples uses in this study. Yellow shading indicates the distribution and location of Pama-Nyungan language families. Orange shading indicates the distribution of non–Pama-Nyungan language families. Dashed lines show the approximate distribution of accepted major language subgroups, with language names in italics. Red symbols indicate previously published mitochondrial or nuclear genomes; blue symbols indicate new unpublished data. Circles indicate contemporary Aboriginal Australian samples, and stars represent ancient individuals. Sample code abbreviations have been included in parentheses.</span>
<span class="attribution"><a class="source" href="http://advances.sciencemag.org/">Joanna Groom/Science Advances</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Mitochondrial vs nuclear DNA</h2>
<p>We found by using maternally inherited DNA (mitochondrial DNA), we could successfully determine the origins of 62.1% of bodily remains of ancient Aboriginal Australians included in this research. </p>
<p>But we could not achieve this for the remaining 37.9% of the remains in the study. For these, the results were either inconclusive (due to a lack of contemporary matches or the matches identified were widespread across large geographic distances), or the results were unreliable. In two instances, the closest contemporary matches were not from the same geographic location, but some 635 kilometres away. </p>
<p>As the return to place and Country of ancestral remains is important to many Aboriginal Australian communities, repatriation to incorrect Country would be extremely problematic. Therefore, we are unable to recommend the use of mitochondrial DNA alone for repatriation.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-dreamtime-science-and-narratives-of-indigenous-australia-95919">The Dreamtime, science and narratives of Indigenous Australia</a>
</strong>
</em>
</p>
<hr>
<p>Nuclear DNA (DNA inherited from both parents) provided the most accurate results, working in 100% of cases and to precise geographic locations. </p>
<p>The results obtained were supported by several different methods, each of which independently showed considerable population structure and local continuity between both the ancient and contemporary populations in each geographic location. </p>
<p>However, when combined, these analyses provide strong evidence that nuclear DNA, as a tool for repatriation, is very effective. If applied to unprovenanced ancestral remains, we believe this will greatly assist with their repatriation. </p>
<h2>A need for national consultation and standards</h2>
<p>Traditional Owner Gudju Gudju Fourmile of the Gimuy Yidniji People of Cairns told us this was an important result, and a solution to a problem that has been a major concern to Aboriginal Australians for more than 50 years. He said: </p>
<blockquote>
<p>Many of our ancestors still remain on foreign land, and in storage of museums and collectors. We need to do the right thing to bring them home so their spirit will rest. </p>
</blockquote>
<p>Despite our success, however, one question remains unanswered: how should this new tool be implemented? We believe that before DNA is used to facilitate repatriation of ancient remains, a detailed set of standards and protocols should be developed as best practice for museums and other institutions to follow. </p>
<p>As this method requires the destruction of unprovenanced ancient bone, albeit in small quantities, it is imperative that these standards be developed in close consultation with Indigenous communities across Australia. It is essential that a consensus be reached and a decision made by Aboriginal Australians at a national level. This requires a national debate, but it should be among our First People.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-dna-study-confirms-ancient-aborigines-were-the-first-australians-60616">New DNA study confirms ancient Aborigines were the First Australians</a>
</strong>
</em>
</p>
<hr>
<h2>From subject to researcher</h2>
<p>In addition to developing an effective tool for provenancing ancestral remains for repatriation, this research is significant because it was driven by Aboriginal Australian Traditional Owners and their communities. Their desire to learn more about themselves developed into a major research project in which they were actively involved and equal partners in the direction the research took. </p>
<p>Without their input and knowledge this research would not have been possible. </p>
<p>This is a significant shift from Aboriginal Australians being scientific subjects, as they were in the past, to them becoming researchers in their own right.</p><img src="https://counter.theconversation.com/content/108168/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Lambert receives funding from the Australian Research Council, and Human Frontier Science, and the Marsden Fund (NZ). </span></em></p><p class="fine-print"><em><span>Joanne Wright and Sally Wasef do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Museums around the world hold remains of Aboriginal people that were often taken without permission and in the absence of accurate records. New DNA methods may help return these items to country.Joanne Wright, Research associate, Griffith UniversityDavid Lambert, Professor of Evolutionary Biology, Griffith UniversitySally Wasef, Research Fellow, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1076412018-11-28T15:10:02Z2018-11-28T15:10:02ZStudy shows mitochondrial DNA can be passed through fathers – what does this mean for genetics?<figure><img src="https://images.theconversation.com/files/247501/original/file-20181127-76764-c9uxf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/cellular-organelle-mitochondria-3d-illustration-706973239?src=O-u9LHsAO6haC07Few8OpA-1-15">3D man/Shutterstock</a></span></figcaption></figure><p>Some things you learn in school turn out <a href="https://theconversation.com/five-science-facts-we-learnt-at-school-that-are-plain-wrong-33258">not to be true</a>, for example that there are just five senses or three states of matter. Now cutting-edge research has added to the list by proving the mitochondria (the power sources in our cells) comes from both our parents and not – as biology students are taught – just from our mothers.</p>
<p>The research, <a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1810946115">published in PNAS</a>, showed conclusively that, in three unrelated families, mitochondria from the father’s sperm had been passed to the children over several generations. Overturning scientific understanding about this fundamental “truth”, opens the possibility for better treatment of mitochondrial disorders, which blight many families with devastating disease. </p>
<p>Mitochondria convert the sugars, fats and proteins that we eat into the molecules our cells use to power themselves. So <a href="http://mitochondrialdisease.nhs.uk/patient-area/what-mitochondrial-disease/">when they go wrong</a>, the result is often catastrophic, resulting in lifelong problems or even the death of an affected baby in the womb.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/66Tjk8wtJYY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p><a href="http://www.newcastle-mitochondria.com/patient-and-public-home-page/melas/">MELAS syndrome</a>, for example, begins in early childhood and results in seizures and dementia. <a href="https://ghr.nlm.nih.gov/condition/kearns-sayre-syndrome">Kearns-Sayre syndrome</a> causes problems with sight and hearing, potentially leaving the sufferer blind and deaf.</p>
<p>Most of a cell’s DNA is contained in its nucleus but mitochondria sit separately inside the cell and have their own DNA. This is because mitochondria are thought to have started as <a href="https://www.nature.com/scitable/topicpage/the-origin-of-mitochondria-14232356">separate organisms</a>, which entered early cells about 1.45 billion years ago and never left. They reproduce themselves and move from one generation to another by “hitching a lift” in the egg.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/247502/original/file-20181127-76743-lgxtq0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247502/original/file-20181127-76743-lgxtq0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247502/original/file-20181127-76743-lgxtq0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247502/original/file-20181127-76743-lgxtq0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247502/original/file-20181127-76743-lgxtq0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247502/original/file-20181127-76743-lgxtq0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247502/original/file-20181127-76743-lgxtq0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mitochondria are the power sources of a cell.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-rendered-illustration-human-cell-crosssection-1215277975?src=2LMaSyJqo8gCmhb0kn0kZQ-1-46">Sebastian Kaulitzk/Shutterstock</a></span>
</figcaption>
</figure>
<p>During fertilisation, the father’s sperm transfers his DNA into an egg, but few or none of the sperm’s mitochondria get in. If any do, then there are mechanisms designed <a href="https://www.sciencedirect.com/science/article/pii/S1534580714002044">to destroy them</a>. The new research found that, in a small number of families, the mitochondria from the father that found its way into the egg were not destroyed, though we don’t yet know enough to say why. There was also some evidence this mitochondrial DNA from the father may have then been copied as the fertilised egg grew into an embryo even more than that from the mother.</p>
<p>There’s a chance that previous research may have also found examples of mitochondria being passed on from fathers but that these results were discounted and assumed to be the result of sample contamination. But with ever-increasing <a href="https://www.omicsonline.org/open-access/generations-of-sequencing-technologies-from-first-to-next-generation-0974-8369-1000395.php?aid=87862">technological advances</a>, cheaper and more in-depth DNA analysis is possible. So it’s likely that more and more cases will now be reported.</p>
<p>This work could affect scientists studying the movement of humans around the planet. Human mitochondrial DNA tends to <a href="https://www.omicsonline.org/open-access/mitochondrial-dna-a-tool-for-phylogenetic-and-biodiversity-search-in-equines-2332-2543-S1-006.php?aid=63938">alter very little</a> over time because even tiny changes <a href="https://www.forbes.com/sites/quora/2017/02/02/how-can-mutations-in-mitochondrial-dna-affect-the-human-body/#62c6962237d4">are often fatal</a> so aren’t passed on to future generations. This means a person’s mitochondrial DNA is likely to be very similar to that of their distant ancestors and other people from their ethnic group.</p>
<p>So by studying mitochondrial DNA in different populations, scientists have also been able to <a href="https://www.scientificamerican.com/article/how-do-researchers-trace/">follow how these groups</a> have moved around the world and even to identify a potential common female ancestor for all humans, known as “<a href="https://www.sciencedaily.com/releases/2010/08/100817122405.htm">mitochondrial Eve</a>”. All of this work has, however, been based on the “fact” that mitochondria pass down the female line only, something we now know to be wrong.</p>
<h2>Better treatments</h2>
<p>The most significant implications of these findings are staggering, because a better understanding of how mitochondria are passed on gives us a much better chance of developing treatments for mitochondrial disorders. It may even be possible to encourage properly functioning mitochondria to multiply inside a fertilised egg at the expense of the broken ones.</p>
<p>Any treatment would likely be controversial, because it would involve <a href="https://theconversation.com/five-reasons-we-should-embrace-gene-editing-research-on-human-embryos-51474">influencing someone’s DNA</a> in a way that would be inherited by subsequent generations. But the only other current treatment is equally controversial and involves inserting the nucleus from a fertilised egg into a donor egg containing normal mitochondria. This is often described as producing “three-parent babies” and is not permitted in most countries, although the <a href="https://theconversation.com/worlds-first-three-parent-baby-raises-questions-about-long-term-health-risks-66189">first such baby was born in April 2016</a>. So manipulating the parent’s mitochondria instead may be seen as more preferable.</p>
<p>When it comes to our use of mitochondrial DNA to study human evolution and migration, the rarity of the cases identified by the new study means it won’t significantly impact our understanding in this area. But if further research suggests that the inheritance of fathers’ mitochondrial DNA is more common, our whole understanding of human migration may need to be adjusted.</p><img src="https://counter.theconversation.com/content/107641/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Porter does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We previously thought mitochondrial DNA could only be passed on by mothers.Michael Porter, Lecturer in Molecular Genetics, University of Central LancashireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/979912018-06-15T10:47:43Z2018-06-15T10:47:43ZHow can a baby have 3 parents?<figure><img src="https://images.theconversation.com/files/222444/original/file-20180608-191954-ugwriv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/baby-crying-after-birth-labor-room-548487937?src=ExK4m7GEK_Vl44wg0TshCQ-1-8">By Fakhrul Najmi</a></span></figcaption></figure><p>It seems impossible, right? We have been taught from the time we were young that babies are made when a sperm and an egg come together, and the DNA from these two cells combine to make a unique individual with half the DNA from the mother and half from the father. So how can there be a third person involved in this process? </p>
<p>To understand the idea of three-parent babies, we have to talk about DNA. Most people are familiar with the double helix-style DNA which make up the 23 pairs of chromosomes that are found in the nucleus of every cell in our body. It provides the instructions for building an entire organism and the proteins that drive our existence from conception until death. However, the DNA in the nucleus is not the only kind of DNA required for us to exist. There is also DNA tucked away in little compartments called mitochondria, that are found inside all of the cells in your body. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=531&fit=crop&dpr=1 600w, https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=531&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=531&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=667&fit=crop&dpr=1 754w, https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=667&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/222442/original/file-20180608-191947-a49y37.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=667&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This is a cross section of an animal cell showing the location of the mitochondria, the brown bean-shaped structures. The 23 chromosomes are housed in the innermost compartment of the cell – the nucleus.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/human-animal-cell-cross-section-structure-213232894?src=hh5y4IwJzzN1eY1KM1OWqw-1-5">Designua/shutterstock.com</a></span>
</figcaption>
</figure>
<p>Remember the mitochondria? Dig deep back to middle or high school biology class. It was that bean-shaped organelle often drawn with a squiggly line on it and called the powerhouse of the cell. Each cell in the body, including eggs and sperm, requires energy to carry out all of its functions. Cells without functional mitochondrial DNA (mtDNA) are like cars without gas. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=578&fit=crop&dpr=1 600w, https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=578&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=578&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=726&fit=crop&dpr=1 754w, https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=726&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/222446/original/file-20180608-191965-zai8oe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=726&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This is a cross section of a mitochondrion. These are referred to as the powerhouses of the cell. They contain their own DNA and produce energy for the cell.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/structure-mitochondrion-organelle-found-most-eukaryotic-253622641?src=qKD3rMu-w9oN795_Ges2zw-1-32">CLUSTERX/shutterstock.com</a></span>
</figcaption>
</figure>
<p>Unlike nuclear DNA, mtDNA is not created by the combination of male and female DNA. Instead, mitochondria are only inherited from your mother, meaning that ones that are in the fertilized egg are the ones that will be replicated in every cell of your body during your development and for the rest of your life. </p>
<p>Just like nuclear DNA, mtDNA can have mutations that can lead to very serious, debilitating diseases, and in some cases, infertility for a woman carrying the defective mitochondria. Enter the third parent.</p>
<h2>The third parent</h2>
<p><a href="https://doi.org/10.1016/j.rbmo.2017.01.013">In 2016, a baby was born to a couple</a> who had struggled with the consequences of mtDNA mutations that cause Leigh syndrome, a progressive neurometabolic disorder. When defective mitochondria of the woman’s egg were replaced with mitochondria from a donor who did not carry the mutation, the resulting child carried DNA from three people: the female nuclear DNA donor, the male nuclear DNA or sperm donor, and the female mitochondria donor. This was the first baby born using this technique.</p>
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<a href="https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223285/original/file-20180614-32327-1ckkl3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">How to make a three-parent baby: 1) The egg from the mother contains the DNA (yellow circle) and faulty mitochondria (red ovals). 2) The DNA is removed from the mother’s egg using a very small pipette. 3) The DNA is removed from the mitochondrial donor egg leaving behind the healthy mitochondria (green ovals). 4) The DNA from the mother is transferred to the donor egg with the healthy mitochondria. 5) The result is an egg that has the nuclear DNA from the mother and mitochondrial DNA from the egg/mitochondria donor, which can then be fertilized with the father’s sperm. 6) As the cells replicate during embryo development, each cell will have the combined mother and father’s DNA in the nucleus of the cells and the egg donor’s mitochondria and associated mtDNA. Note: Fertilization can occur before or after transfer of DNA to the donor egg. If it happens before then both the mother and the father’s DNA will be transferred to the donor egg after the donor DNA has been removed. If it occurs after, then the egg will be fertilized after the mother’s DNA is transferred into the donor egg, as described here.</span>
<span class="attribution"><span class="source">Jennifer Barfield</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>This technique, termed mitochondrial replacement, can be thought of like an organ transplant, or rather organelle transplant. However, there are some <a href="http://doi.org/10.1001/jama.2016.20935">significant differences</a> that have created concern among legislators, resulting in <a href="https://www.congress.gov/bill/114th-congress/house-bill/2029/text">a ban on mitochondrial replacement in the U.S.</a>. </p>
<p>Unlike an organ transplant, the effects of mitochondrial replacement will persist in future generations of offspring if the resulting baby is a female and she chooses to have children – males do not pass on their mitochondria. Also, the replacement will affect every tissue in the body, rather than just one body system, such as the cardiovascular system after a heart transplant. </p>
<p>Even so, these donated mitochondria are naturally occurring and already persisting in our population. They are not genetically engineered or altered in any way. Thus, as long as they are functioning properly, there is no demonstrated risk to the offspring from a health standpoint beyond the naturally occurring risks of spontaneous mutations, <a href="http://doi.org/10.1038/525444a">though this is a point of debate</a>.</p>
<p>Since 2016, it’s difficult to say how many of these three-parent procedures have been done and how many resulted in successful pregnancies. But with the recent birth of a baby in the Ukraine that involved three parents, many countries are now exploring if and how to use this technology. The ban in the U.S. has halted the use here but other countries have made different decisions; the U.K. has approved it.</p>
<h2>Is the mitochondrial donor a parent?</h2>
<p>So how much a parent is a woman who donates her mitochondria? </p>
<p>The short answer is not much. More than <a href="https://ghr.nlm.nih.gov/primer/basics/gene">99 percent of the proteins in your body are encoded by the DNA in the nucleus of your cells</a>. Traits such as hair color, eye color and height, for example, are all encoded by nuclear DNA, while genes written on mtDNA are primarily related to <a href="https://doi.org/10.1016/S0005-2728(98)00161-3">energy production and metabolism</a>. </p>
<p>Thus three-parent babies will still resemble the men and women whose sperm and egg combined to produce the 23 chromosomes in the nucleus of that first cell. It’s important for people to understand these distinctions as headlines announcing births of three-parent babies will likely continue to surface. Speculation of what it means could run rampant without understanding the underlying science. </p>
<p>One thing is certain: For women who struggle with infertility caused by mutations in their mitochondrial DNA, or have the potential to pass on significant mitochondrial genetic defects, <a href="http://doi.org/10.1001/jama.2016.20935">this new technique provides hope</a> that they may one day be able to have a healthy child that is a genetic representation of them and their partner – with a little help from a third party.</p><img src="https://counter.theconversation.com/content/97991/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Barfield does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The concept of three-parent babies defies what we learned in health class. But how and when is the third parent involved? At what stage? Jennifer Barfield gives us an update on the birds and the bees.Jennifer Barfield, Assistant Professor, Assisted Reproductive Technologies, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/959192018-05-03T20:21:03Z2018-05-03T20:21:03ZThe Dreamtime, science and narratives of Indigenous Australia<figure><img src="https://images.theconversation.com/files/217130/original/file-20180501-135803-tkypa4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lake Mungo and the surrounding Willandra Lakes of NSW were established around 150,000 years ago. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sunset-over-famous-walls-china-mungo-580536352?src=BM3RK99LNXsfkXUcrXCK0Q-1-0">from www.shutterstock.com </a></span></figcaption></figure><p><em>This article is an extract from an essay <strong>Owning the science: the power of partnerships</strong> in <a href="https://griffithreview.com/editions/first-things-first/">First Things First</a>, the 60th edition of Griffith Review.</em></p>
<p><em>We’re publishing it as part of our occasional series Zoom Out, where authors explore key ideas in science and technology in the broader context of society and humanity.</em></p>
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<p>Scientific and Indigenous knowledge systems have often been in conflict. In my view, too much is made of these conflicts; they have a lot in common.</p>
<p>For example, Indigenous knowledge typically takes the form of a narrative, usually a spoken story about how the world came to be. In a similar way, evolutionary theories, which aim to explain why particular characters are adapted to certain functions, also take the form of narratives. Both narratives are mostly focused on “origins”.</p>
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Read more:
<a href="https://theconversation.com/friday-essay-when-did-australias-human-history-begin-87251">Friday essay: when did Australia’s human history begin?</a>
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<p>From a strictly genetic perspective, progress on origins research in Australia has been particularly slow. Early ancient DNA studies were focused on remains from permafrost conditions in Antarctica and cool temperate environments such as northern Europe, including Greenland.</p>
<p>But Australia is very different. Here, human remains are very old, and many are recovered from very hot environments.</p>
<p>While ancient DNA studies have played an important role in informing understanding of the evolution of our species worldwide, little is known about the levels of ancient genomic variation in Australia’s First Peoples – although some progress has been made in recent years. This includes the landmark recovery of genomic sequences from both contemporary and ancient Aboriginal Australian remains.</p>
<h2>Found, or revealed?</h2>
<p><a href="http://www.visitmungo.com.au/who-was-mungo-lady">Mungo Man and Mungo Lady</a> have been the subject of both Indigenous and scientific narratives.</p>
<p>From a scientific perspective, in 1968 the burnt remains of a woman were recovered at Lake Mungo by Jim Bowler, a young geologist. Six years later, after heavy rain, Bowler was riding his motorbike around the lake and again found human remains, this time of a man.</p>
<p>From an Indigenous perspective, it was not that Jim Bowler discovered these ancient people but that they found him. And of course, one is struck by the apparent coincidence that they both revealed themselves to the same person, albeit six years apart.</p>
<p>Professor <a href="https://theconversation.com/profiles/jim-bowler-145173">Jim Bowler</a> is a distinguished scientist who has close ties with, and an understanding of, Australia’s First Peoples, so Mungo Lady and Mungo Man chose well.</p>
<h2>Since the Dreamtime</h2>
<p>Perhaps the most well-known conflict between scientific and Indigenous perspectives relates to the origins of Aboriginal Australians.</p>
<p>From an Indigenous perspective, Aboriginal Australians have always been on this land – since the Dreamtime. From a scientific perspective, there is strong evidence that they have been here for more than 65,000 years – not quite “always”.</p>
<p>From my perspective, though, 65,000 years seems pretty close to “always”, and, moreover, it is likely that people became Aboriginal Australians when they first set foot on this land. So, in this sense, they have indeed always been here.</p>
<p>When a <a href="http://www.pnas.org/content/98/2/537">publication by Professor Alan Thorne</a>, a prominent Australian anthropologist, and his colleagues from the Australian National University appeared in the journal PNAS in 2001, it drew worldwide attention. The authors reported the recovery of short <a href="https://ghr.nlm.nih.gov/primer/basics/mtdna">mitochondrial DNA</a> from Mungo Man, as well as the other ancient remains of a number of people from the Willandra Lakes region.</p>
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Read more:
<a href="https://theconversation.com/explainer-what-are-mitochondria-and-how-did-we-come-to-have-them-83106">Explainer: what are mitochondria and how did we come to have them?</a>
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<p>The results from their analysis, which included an evolutionary tree of recovered DNA sequences, suggested that Mungo Man was genetically different to the other ancient people they studied, who were closely related to the Aboriginal Australians of today.</p>
<p>This implied that contemporary Aboriginal Australians replaced another population of humans that lived here first.</p>
<p>This conclusion caused widespread offence among Aboriginal people, though it was difficult for them to reject the scientific claims. Some <a href="http://www.abc.net.au/science/articles/2001/01/01/2813404.htm">scientists argued</a> that Thorne’s results were highly unlikely to be correct, given the age of the remains and the hot environment in which they had been interred. It was not, however, possible to refute these claims without a detailed understanding of the methods used and the opportunity to redo the experiment.</p>
<p>Some politicians and commentators seized on the result to <a href="https://theconversation.com/factcheck-might-there-have-been-people-in-australia-prior-to-aboriginal-people-43911">argue against constitutional recognition of Aboriginal Australians</a>, suggesting there was considerable doubt about their First Peoples status.</p>
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Read more:
<a href="https://theconversation.com/factcheck-might-there-have-been-people-in-australia-prior-to-aboriginal-people-43911">FactCheck: might there have been people in Australia prior to Aboriginal people?</a>
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<h2>Big personalities</h2>
<p>Big personalities have dominated Australian archaeology and anthropology, and influenced its development – Alan Thorne prominent among them. He first became involved in the Lake Mungo excavations under the archaeologist Jim Bowler in 1969, reconstructing the remains of the skeleton of Mungo Lady.</p>
<p>Five years later he also reconstructed Mungo Man and led excavations at other important burial grounds in Victoria. Thorne was very well known for his work on the multiregional evolution hypothesis, a model of human evolution that disputed the more widely known recent African origin (or “<a href="https://theconversation.com/worlds-scientists-turn-to-asia-and-australia-to-rewrite-human-history-88697">out of Africa</a>”) hypothesis.</p>
<p>For more than a decade after Thorne’s research was published, his work on Mungo Man and other ancient people from Willandra went largely unchallenged, despite the distress it caused to Aboriginal Australians.</p>
<p>Then, in 2010, with the permission of the Paakantji, Ngyiampaa and the Mutthi Mutthi peoples of the Willandra Lakes, my colleagues and I from the Australian Research Centre for Human Evolution were able to resample these important remains.</p>
<p>With the advantages of technology that had developed in the preceding decade, we repeated much of the original work. The new technology meant that we were able to recover much smaller amounts of DNA (if it was still present in the remains) and sequence it.</p>
<p>In 2016, we also <a href="http://www.pnas.org/content/113/25/6892">published the results</a> in PNAS journal. Our findings provided <a href="https://theconversation.com/new-dna-study-confirms-ancient-aborigines-were-the-first-australians-60616">strong evidence</a> to refute the claims made by Thorne and his colleagues, showing it was not possible to recover any DNA that unequivocally belonged to Mungo Man.</p>
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Read more:
<a href="https://theconversation.com/new-dna-study-confirms-ancient-aborigines-were-the-first-australians-60616">New DNA study confirms ancient Aborigines were the First Australians</a>
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<p>We did, however, recover five distinct DNA sequences from his remains. But these sequences revealed no ancient DNA damage patterns, indicating that they were not ancient sequences – and genetic analysis showed that they were European in origin. Clearly these were sequences from people who left their DNA on the bone material after handling Mungo Man’s remains.</p>
<h2>New techniques, new light</h2>
<p>Our study set the record straight. We refuted the claim that Mungo Man was a member of an earlier group of people that previously inhabited Australia and not an Aboriginal Australian.</p>
<p>Perhaps of equal importance, we were able to recover substantial coverage of the mitochondrial genome from another ancient Willandra Lakes man, who was buried only a few hundred metres from Mungo Man.</p>
<p>The remains contained about 1% human DNA; from them, we were able to recover two complete mitochondrial genomes. One of these was a previously unidentified Aboriginal Australian mitochondrial genetic type, almost certainly from the remains themselves. The other was European in origin, and certainly a contaminant.</p>
<p>It appeared that this man was from within the Holocene period (that is, the period since the last Ice Age that ended around 11,700 years ago); we know this because the skeletal remains were not heavily mineralised. His teeth exhibited a pattern of wear typical of Aboriginal hunter-gatherer populations and included no evidence of cavities or tooth decay. </p>
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Read more:
<a href="https://theconversation.com/worlds-scientists-turn-to-asia-and-australia-to-rewrite-human-history-88697">World's scientists turn to Asia and Australia to rewrite human history</a>
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<p>Combined with the lack of mineralisation in the bone and its position in the soil layers at Lake Mungo, various authors have suggested that the remains were a few thousand years old. This is important, because it means that he represents the best “proxy” currently available for Mungo Man.</p>
<p>The fact that he was buried so close to the oldest-known Australian, albeit much later, suggests a common place and country. This is particularly significant given that the environmental conditions were very different at the times of the two burials, which were about 40,000 years apart.</p>
<p>Hence, nuclear gene studies of this man, currently underway, will be especially relevant to our understanding of Mungo Man himself. And because the nuclear genome is much larger than the mitochondrial, it will reveal much more information.</p>
<p>Such nuclear genome studies enable us to establish kinship relationships between people living now and ancient peoples. Such studies will take substantial time and effort, and will require the development of new innovative genomic tools.</p>
<p>Ethical considerations demand Aboriginal involvement in both the design and operation of such new techniques, as well as new research relationships with Indigenous communities.</p>
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Read more:
<a href="https://theconversation.com/buried-tools-and-pigments-tell-a-new-history-of-humans-in-australia-for-65-000-years-81021">Buried tools and pigments tell a new history of humans in Australia for 65,000 years</a>
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<img src="https://counter.theconversation.com/content/95919/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Lambert receives funding from the Australian Research Council.</span></em></p>New techniques for genetic analysis are helping us build more detailed and accurate stories about the ancient histories of the first Australians.David Lambert, Professor of Evolutionary Biology, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/957852018-05-03T03:15:05Z2018-05-03T03:15:05ZA DNA test says you’ve got Indigenous Australian ancestry. Now what?<figure><img src="https://images.theconversation.com/files/216969/original/file-20180501-135837-1ocfg5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Families have secrets - and sometimes we don't know our complete genetic histories. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/vintage-photos-family-archive-shot-beginning-46788088?src=NrskIcPo5iSekbL9okj_cw-1-33">from www.shutterstock.com </a></span></figcaption></figure><p><em>Technologies for amplifying, sequencing and matching DNA have created new opportunities in genomic science. In this series <a href="https://theconversation.com/au/topics/when-dna-talks-53134">When DNA Talks</a> we look at the ethical and social implications.</em> </p>
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<p>Getting your “DNA done” is all the rage in the United States.</p>
<p>The sensationalism started with celebrities such as <a href="https://www.youtube.com/watch?v=MsEZBSTc3a0">Jessica Alba</a> and <a href="https://www.youtube.com/watch?v=Exz0yNdvksg">Snoop Dog</a> – and has now spread to hundreds of video bloggers disclosing their ancestry to <a href="https://www.youtube.com/watch?v=_5-GwlAVS3w">drum rolls</a>, <a href="https://www.youtube.com/watch?v=pK7bLFfzLwo">exclamations</a>, <a href="https://www.youtube.com/watch?v=b0EDNX47S20">cheers</a> and <a href="https://www.youtube.com/watch?v=MdpuGIZfR90">tears</a>. </p>
<p>These tests claim to reveal deep ancestral origins, and many public users of this technology are black Americans seeking information about their African roots. </p>
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<figcaption><span class="caption">Snoop Dog sent his DNA to be tested – and did the maths faster than this TV host.</span></figcaption>
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<p>The uptake of direct-to-consumer genetic testing has been slower in Australia. Here it is <a href="https://theconversation.com/dna-nation-raises-tough-questions-for-indigenous-australians-59877">complicated by debates</a> both beyond and within the Indigenous community – with some leaders calling for greater scrutiny to prevent “<a href="http://www.theaustralian.com.au/national-affairs/indigenous/push-for-aboriginal-id-tests-by-indigenous-leaders/news-story/a0bd39a868ad44a22dab85cf76cb9dc7">fakes</a>” or “<a href="http://www.theaustralian.com.au/national-affairs/indigenous/brawl-over-wannabe-and-tickabox-aborigines/news-story/d4a8a3a47cf478d08a17b7c466d09e66">wannabes</a>” calling themselves Indigenous.</p>
<p>One of the authors of this article – Shaun Lehmann – was dropped into this debate inadvertently, after receiving the result of his own DNA test a few years ago. </p>
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Read more:
<a href="https://theconversation.com/dna-nation-raises-tough-questions-for-indigenous-australians-59877">DNA Nation raises tough questions for Indigenous Australians</a>
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<h2>Professional and personal</h2>
<p>Shaun had more professional reasons for doing the test than most: at the time he was lecturing in human genetic diversity at the Australian National University and wanted to use his own genetic data as teaching tool.</p>
<p>He also had personal questions about his maternal grandmother, who had died when he was a small child. She had grown up without her mother and said little about her background.</p>
<p>Because they are related through a direct maternal line, Shaun knew that it was his grandmother, and by extension mysterious great-grandmother, who gave him his <a href="https://www.sciencedirect.com/science/article/pii/S0005272898001613">mitochondrial genome</a>.</p>
<p>Mitochondria are the tiny organelles that make energy in our cells. While the genome in the nucleus of our cells – our 23 pairs of chromosomes – is made up of a mix of our biological mother’s and father’s DNA, the relatively small mitochondrial genome is passed down through the egg and so reflects a single line of maternal ancestors.</p>
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Read more:
<a href="https://theconversation.com/explainer-what-are-mitochondria-and-how-did-we-come-to-have-them-83106">Explainer: what are mitochondria and how did we come to have them?</a>
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<p>What Shaun didn’t know at the time, and what the test revealed, was that his particular mitochondrial genome fell into a haplogroup (a grouping of similar mitochondrial genomes) called “S2”, which has <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/9780470015902.a0020815.pub2">only been observed in Aboriginal Australians</a>.</p>
<h2>Interpreting genetic results</h2>
<p>Being mitochondrial DNA, Shaun knew exactly where to look in his genealogy to find out more. Sure enough, he soon found records that his grandmother’s maternal family were Aboriginal people originally from the Albany area of Western Australia. With this information in hand, Shaun was able to trace his family tree to living <a href="https://www.noongarculture.org.au/">Noongar</a> relatives.</p>
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<a href="https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=511&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=511&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=511&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=642&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=642&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217371/original/file-20180502-153873-lchl0i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=642&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">How mitochondrial DNA and nuclear DNA are passed on.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Mitochondrial_DNA_versus_Nuclear_DNA.gif">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Shaun’s discovery was certainly aided by the fact that he is a geneticist and could interpret his DNA test results. Most important, though, was that his Aboriginal ancestry happened to be in the direct maternal line. </p>
<p>Mitochondrial DNA is a reliable source of genetic information about Aboriginal ancestry, but it can’t help at all if your Aboriginal ancestors sit anywhere else in your family tree. That is, it’s only useful to track direct from mother to grandmother to great grandmother and so on.</p>
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Read more:
<a href="https://theconversation.com/friday-essay-when-did-australias-human-history-begin-87251">Friday essay: when did Australia’s human history begin?</a>
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<h2>Different kinds of DNA tests</h2>
<p>Most of the “ethnic breakdown” DNA results being shared publicly by bloggers come from testing companies that compare their nuclear DNA with material from various ethnic groups. The tests focus on variations in specific regions of genes – known as single nucleotide polymorphisms, or SNPs. </p>
<p>To our knowledge, DNA testing companies do not currently have reliable reference SNP data from Indigenous Australians. </p>
<p><a href="http://www.dnatribes.com/">One company</a> offering tests claiming to identify Indigenous Australians uses an approach that compares sequences in genes known as <a href="https://www.nature.com/scitable/topicpage/forensics-dna-fingerprinting-and-codis-736">Short Tandem Repeats, or STRs</a>. STR data from around the world are widely available in the forensic science literature because these are widely used in <a href="https://www.sciencedirect.com/science/article/pii/S1687157X12000194">criminal investigations and paternity testing</a>. </p>
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<strong>
Read more:
<a href="https://theconversation.com/is-your-genome-really-your-own-the-public-and-forensic-value-of-dna-95786">Is your genome really your own? The public and forensic value of DNA</a>
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<p>Ethical and scientific concerns have been raised about the use of STR data for commercial ancestry testing. For example, it is difficult to know how companies get their <a href="https://theconversation.com/dna-nation-raises-tough-questions-for-indigenous-australians-59877">reference samples</a>. </p>
<p>The case of American blogger <a href="http://lisagarrigues.blogspot.com.au/2011/01/dna-tribes-and-all-my-relations.html">Lisa Garrigues</a> is illustrative. Garrigues did a test back in 2010 – it reportedly gave her second “Highest Resolution Global Population Match” as “European-Aboriginal”.</p>
<p>She was excited by this discovery, but also sceptical – her family has no known connections to the Southern Hemisphere. Lisa and her father subsequently did <a href="http://lisagarrigues.blogspot.com.au/2011/05/">more thorough DNA testing</a>, and it didn’t suggest Aboriginal ancestry. </p>
<p>In our personal correspondence with one of the genetic genealogists who assisted Lisa, <a href="http://isogg.org/wiki/McDonald's_BGA_project">Doug McDonald</a> suggests these kind of inconsistencies are extremely common – STR markers are not designed for ancestry tests, but for matching individual people.</p>
<h2>After the test: now what?</h2>
<p>We need to be on the lookout for misinformation and unethical practices around genealogy testing. But even where the science is reliable, such as Shaun’s mitochondrial DNA test, the implications of identifying genetic Indigenous ancestry are far from clear.</p>
<p>Shaun was proud to learn about his ancestry and has since got in contact with his relatives. He is also looking into his grandmother’s past to find out whether her separation from her mother was influenced by the policies that led to the Stolen Generations. </p>
<p>Existing research suggests there are many possible endings for journeys like Shaun’s. <a href="http://www.podsocs.com/podcast/finding-aboriginal-identity/">Bindi Bennett’s work</a> highlights how young, light-skinned people who had no previous ties to the Aboriginal community can develop a strong Indigenous identity, even in the face of resistance from that community. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/culture-not-colour-is-the-heart-of-aboriginal-identity-30102">Culture, not colour, is the heart of Aboriginal identity</a>
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<p>But <a href="http://librarycatalogue.griffith.edu.au/record=b1357619">Fiona Noble’s 1996 research</a> with Queenslanders who discovered their Aboriginal ancestry late in life suggests many of this demographic see their heritage as extremely important, but not all-defining. </p>
<p>They are more comfortable describing themselves as being “of Aboriginal descent” rather than “Aboriginal”. </p>
<p>As <a href="http://www.borderlands.net.au/vol7no2_2008/ganter_turning.pdf">Regina Ganter notes</a>, the “in-between” status of these “half-steps” is not well-recognised contemporary policy and discourse – which tends to frame Aboriginality as an either/or identity.</p>
<p>Although Noble and Bennett’s research participants discovered their heritage through documents or family stories, not genetics, their work offers a window onto a future where more Australians discover Aboriginal ancestry through DNA tests.</p>
<p>Without a doubt, the inevitable collision of Aboriginal and Torres Strait Islander Australia with direct-to-consumer genetic testing will continue to raise challenging questions about ancestry and identity in the 21st century. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/dna-facial-prediction-could-make-protecting-your-privacy-more-difficult-94740">DNA facial prediction could make protecting your privacy more difficult</a>
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<img src="https://counter.theconversation.com/content/95785/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Kowal receives funding from the Australian Research Council and the National Health and Medical Research Council.</span></em></p><p class="fine-print"><em><span>Elizabeth Watt and Shaun Lehmann do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Ancestry and identity are not the same thing. A scientist tells the story of what happened when he sent his DNA to an ancestry company.Elizabeth Watt, Research Fellow, Deakin UniversityEmma Kowal, Professor of Anthropology, Deakin UniversityShaun Lehmann, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/927942018-03-22T10:42:06Z2018-03-22T10:42:06ZMitochondria mutation mystery solved: Random sorting helps get rid of duds<figure><img src="https://images.theconversation.com/files/211047/original/file-20180319-31633-1sxhx6g.jpg?ixlib=rb-1.1.0&rect=2%2C16%2C590%2C453&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When a cell divides, mitochondria are randomly allotted to the resulting new cells.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/wellcomeimages/25937295324">Odra Noel. Wellcome Images</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>You probably know about the 23 pairs of chromosomes safely stowed in your cells’ nuclei. That’s where the vast majority of your genes can be found. But there are 37 special genes — a very tiny fraction of the human genome — located in mitochondria, the structures inside your cells that breathe and produce energy.</p>
<p>Repeated copying of mitochondrial DNA introduces errors; if not kept in check, these mutations can give rise to incurable diseases like <a href="https://ghr.nlm.nih.gov/condition/leigh-syndrome">Leigh syndrome</a> and <a href="https://ghr.nlm.nih.gov/condition/leber-hereditary-optic-neuropathy">Leber’s optic neuropathy</a>. Worldwide, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4737121/">more than 1 in 10,000</a> people are affected by disorders resulting from mitochondrial genome defects.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=671&fit=crop&dpr=1 600w, https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=671&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=671&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=843&fit=crop&dpr=1 754w, https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=843&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/211067/original/file-20180319-31614-14j8noq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=843&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mitochondrial DNA is inherited only from the mother, based on what mitochondria happen to be in the egg.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Mitochondrial_DNA_lg.jpg">National Human Genome Research Institute</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Unlike nuclear chromosomes that we get from both parents, only mothers’ mitochondria are passed on to offspring. This makes the usual process of sexual recombination, in which pieces of maternal and paternal chromosomes combine to repair genome defects, impossible. For decades, biologists predicted that without this repair mechanism, mitochondrial genes should rapidly accumulate harmful mutations and <a href="http://rspb.royalsocietypublishing.org/content/early/2009/02/09/rspb.2008.1758.short">lose their function</a>.</p>
<p>Despite these predictions, mitochondrial disorders in humans, while debilitating, are relatively rare. A <a href="https://doi.org/10.1038/s41556-017-0017-8">set of experiments</a> with human embryos has recently found low levels of mitochondrial mutations in most of the studied cells, that, strikingly, were otherwise perfectly healthy. If mitochondrial defects are so common, what keeps them from reaching dangerous disease-causing levels?</p>
<h2>Dealing out mitochondria by chance</h2>
<p>A typical human cell contains hundreds of mitochondria. Each mitochondrion in turn has many genome copies jointly responsible for <a href="https://en.wikipedia.org/wiki/Cellular_respiration">energy production</a>. If only a few of these copies become faulty, the rest of the mitochondria can still produce enough energy, and the cell does perfectly fine. In fact, some of the most severe disorders develop only when <a href="https://doi.org/10.1111/dgd.12420">60 to 90 percent</a> of mitochondria within each cell become mutated. This means that low levels of mitochondrial mutations are essentially invisible, and can lurk within human cells for generations without causing a disease. </p>
<p>Recent <a href="https://doi.org/10.1534/genetics.117.300273">theoretical work</a> by <a href="https://scholar.google.com/citations?user=yi-SnYcAAAAJ&hl=en&oi=ao">me</a> and my colleagues predicted a number of solutions that likely evolved to expose and eventually eliminate these hidden defects. The general principle we proposed is based on simple sorting of healthy and faulty mitochondria.</p>
<p>Whenever a cell within a developing embryo divides, mitochondria are partitioned into the two daughter cells more or less randomly. By chance, one of the two daughter cells inherits more mitochondrial defects than the other. Initially, this difference is barely noticeable. But repeat the process many times and a sizeable proportion of all daughter cells will have enough mutations to ensure that the cell does not survive. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/211432/original/file-20180321-165583-11ye0fl.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The mitochondria make copies in preparation for a cell dividing. Which version winds up in each daughter cell is essentially random. By chance, the bottom cell has even fewer of the red version than the original cell.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1371/journal.pbio.2000410">Radzvilavicius et al</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>On the opposite side of the spectrum, this leaves cells that have fewer mutations even than the original cell that started dividing. This simple mechanism of cell division and random sorting of mitochondria can therefore produce cells packed with healthy mitochondria that can then go on to divide further and to eventually produce mutation-free reproductive cells (eggs in females).</p>
<p>But there’s more. Scientists now believe that many features of the human reproductive system evolved to increase the efficiency of this random mitochondrial sorting. For instance, mutations would pile up faster if both paternal and maternal mitochondria were inherited by the offspring – mixing of two unrelated types of organelles would make it easier for rare defects to hide. It is very likely that we inherit mitochondrial genes only from our mothers precisely because it slows down the accumulation of defective genes.</p>
<p>The number of genome replication cycles also matters, because new defects are introduced each time genes are copied. In a paper published in 2016, my colleagues and I suggest this <a href="https://doi.org/10.1371/journal.pbio.2000410">could be the reason</a> why the number of cell divisions to produce an egg in females is strictly limited to 24. In males – whose mitochondria are not transmitted to the offspring – sperm are produced continually with more than 400 cell divisions by the age of 30. By capping the number of times a cell divides before an egg is made, females reduce the risk of introducing new copying errors in their mitochondrial genes.</p>
<p>Likewise, theory predicts that random sorting of healthy and sickly mitochondria works best when the number of mitochondria in a cell is low. With only a few mitochondria, even slightly defective genes cannot hide; their harmful effects are immediately obvious at the level of the cell, which can then be eliminated.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/211068/original/file-20180319-31596-p49o9j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Less hearty mitochondria may already be getting weeded out in an eight-cell embryo.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Embryo,_8_cells.jpg">eked</a></span>
</figcaption>
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<h2>Observing what theory predicts</h2>
<p>Confirming these predictions, a recent study involving human embryos has indeed discovered that the <a href="https://doi.org/10.1038/s41556-017-0017-8">number of mitochondria is sharply reduced throughout development</a> – from 1 million in a fertilized egg to only around 1,500 per cell in a 4-week-old embryo. Researchers also found that cells taken from older embryos had fewer mitochondrial mutations, meaning that cells with the most defects were somehow eliminated throughout embryonic development.</p>
<p>It is not yet clear how cells with the most mitochondrial mutations are selectively removed in human embryos. But because most of the harmful mutations were eliminated at the stage of embryonic development when cells start breathing more actively, scientists think that damaged mitochondria simply fail to produce enough energy for the cell to survive. </p>
<p>Many questions remain. For instance, why do cells with high levels of defective mitochondria sometimes escape these quality-control mechanisms, resulting in incurable disorders? Ultimately, greater understanding of these mechanisms should suggest better ways of estimating the risk of mitochondrial diseases, or even develop new interventions to prevent them completely.</p><img src="https://counter.theconversation.com/content/92794/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arunas L. Radzvilavicius receives funding from Defense Advanced Research Projects Agency.</span></em></p>The genes in our cells’ mitochondria are passed on in a different way than the vast majority of our DNA. New studies shed light on how the unique process isn’t derailed by mutations.Arunas L. Radzvilavicius, Postdoctoral Researcher of Evolutionary Biology, University of PennsylvaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/863712017-11-02T23:38:41Z2017-11-02T23:38:41ZIt’s mostly mothers who pass on mitochondria – and a new theory says it’s due to the first sexual conflict<figure><img src="https://images.theconversation.com/files/193092/original/file-20171102-26478-lwqk5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is this how we got the sperm and the egg?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sperm-egg-1762515">Sebastian Kaulitzki/Shutterstock</a></span></figcaption></figure><p>Evolutionary interests of males and females do not always coincide. This is known as sexual conflict: male innovations that allow them to reproduce more sometimes hurt females, and vice versa.</p>
<p>Male fruit flies, for instance, inject their partners with <a href="http://www.nytimes.com/1995/01/24/science/sex-and-the-fruit-fly-price-of-promiscuity-is-premature-death.html">toxic chemicals</a> during sex. These toxins destroy sperm of the female’s previous mates, improving his own chances for becoming the sole father of her offspring. But the toxins also make female flies sick and reduce their lifespan. Females, in turn, have evolved defenses to counter the chemicals, sometimes at the expense of males’ success. </p>
<p>Biologists believe that sexual conflicts are rooted in the <a href="http://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(02)00004-6">size and number of reproductive cells</a> – eggs and sperm. Males typically produce large numbers of sperm that can fertilize multiple eggs. Females, on the other hand, produce a small number of large reproductive cells, and so invest more energy and resources in each. </p>
<p><a href="http://www.ucl.ac.uk/%7Eucbhpom/people.html">My team</a> of evolutionary biologists at University College London <a href="https://doi.org/10.1186/s12915-017-0437-8">has now identified a different kind of sexual conflict</a>, dating back to the days when the most complex organisms were made of single cells, possibly as far as 1.5 billion years ago. This ancient sexual conflict – before the two sexes even existed – had to do with whose mitochondria would be passed on to offspring.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=544&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=544&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=544&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=684&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=684&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=684&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eukaryotic cells have a nucleus (blue) and numerous mitochondria (green).</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nihgov/20495441928">Dylan Burnette and Jennifer Lippincott-Schwartz, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>Whose mitochondria will be passed on?</h2>
<p>We studied inheritance of genes located in <a href="https://www.livescience.com/50679-mitochondria.html">mitochondria</a> – the structures inside our cells that breathe and produce energy. In many animals and plants, when the egg is fertilized, only the mother’s mitochondrial genes survive, while the father’s mitochondria are lost.</p>
<p>This is not by accident: Females have evolved many mechanisms to recognize a partner’s mitochondria entering the egg. Once detected, an army of enzymes is sent to digest them. Previous research has shown that <a href="https://doi.org/10.1098/rspb.2013.1920">getting rid of male mitochondria</a> is a way to keep descendents’ mitochondrial genes mutation-free. In the long run, inheritance of healthy maternal mitochondria is good news for the offspring.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=511&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=511&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=511&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=642&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=642&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=642&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">For the most part mitochondria come from the mother’s line. But there are exceptions.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Mitochondrial_DNA_versus_Nuclear_DNA.gif">University of California Museum of Paleontology and the National Center for Science Education</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>But there are many exceptions that remain unexplained. In some species, <a href="https://doi.org/10.1038/hdy.2012.60">paternal mitochondria remain undigested</a>, as if the father had found a way to protect them from being detected. Stranger still, in organisms such as fruit flies and many plants, it is the father that destroys most of his own mitochondria during production of sperm.</p>
<p>If maternal inheritance is as beneficial as previous research shows, why are there so many exceptions?</p>
<h2>Taking the long or the short view</h2>
<p>In our new study, we show that these exceptions arise because of a <a href="https://doi.org/10.1186/s12915-017-0437-8">sexual conflict over the control of mitochondrial inheritance</a>.</p>
<p>Using mathematical modeling, we found that evolution in females tends to focus on long-term effects. Destroying paternal mitochondria makes it easier to weed out harmful mutations in the future, but this effect unfolds over many generations. This strategy works well in females, because the same healthy set of maternal mitochondria is passed down the female line over and over again. </p>
<p>But males don’t have a long evolutionary time horizon to deal with in this case. Since most of their mitochondria are replaced by maternal ones at the start of every generation, evolution cannot detect long-term benefits from males’ mitochondrial genes. Because there’s no long-term link, they can benefit only in the immediate future, and that often means passing on some of their mitochondria right now. Males therefore seek to improve the fitness of their offspring in the short-term, even if the long-term effects are harmful.</p>
<p>It’s these different interests of males and females that can lead to an evolutionary arms race, as selection in the two sexes acts in opposite directions. Evolution in females strives to keep the future generations free of male mitochondria, while males make every effort to get some of theirs into the mix.</p>
<p>“Over and over again, males have come up with ways to subvert female destruction of their mitochondria,” said my co-author, geneticist <a href="http://www.ucl.ac.uk/%7Eucbhpom/">Andrew Pomiankowski</a>. “So females had to develop new ways to block male mitochondria. Our model explains nicely why there are so many different mechanisms used to exclude male mitochondria, and why males sometimes do it themselves.”</p>
<p>It’s all about the control of mitochondrial inheritance – and for males it’s better to be in the driver’s seat to decide how many mitochondria they contribute to the mix than be completely excluded.</p>
<h2>A sexual conflict that led to the sexes</h2>
<p>There is evidence that this conflict dates back to the days when all organisms were made of single cells. Male and female sexes did not exist, because all reproductive cells were of the same size. </p>
<p>“One of the strategies an organism can use to win in this conflict is to simply have more mitochondria than their partner, for example, by increasing the size of their sex cells,” Andrew Pomiankowski said. “Strikingly, this might have been the impetus to evolve two sexes in the first place.” Larger sex cells – the future eggs – garnered an advantage in the battle over mitochondrial inheritance, simply by swamping smaller sex cells – the forerunners of sperm – that had fewer mitochondria to contribute.</p>
<p>Most biologists currently think that <a href="https://doi.org/10.1098/rspb.2002.2161">two sexes evolved through division of labor</a> – a so-called “disruptive selection” theory. Large female sex cells can survive longer but cannot move much, while smaller sperm are fragile but move faster and can find more mating partners.</p>
<p>Our hypothesis on the origin of sexes, if true, adds a new angle to this origins story, tracing it back to an ancient conflict over mitochondrial inheritance. Females may have won this ancient battle by simply producing larger sex cells packed with mitochondria, ensuring that mitochondrial transmission is effectively one-sided (and reaping the long-term fitness benefits). But ultimately, as with all scientific hypotheses, this one will have to stand the test of thorough experimental verification.</p><img src="https://counter.theconversation.com/content/86371/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arunas L Radzvilavicius receives funding from David and Lucille Packard Foundation.</span></em></p>An ancient sexual conflict over mitochondrial inheritance may be responsible for the evolution of the two sexes as we know them.Arunas L. Radzvilavicius, Postdoctoral Researcher of Evolutionary Biology, University of PennsylvaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/831062017-09-22T03:57:55Z2017-09-22T03:57:55ZExplainer: what are mitochondria and how did we come to have them?<figure><img src="https://images.theconversation.com/files/186721/original/file-20170920-905-19pmmiz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mitochondria live inside our cells but have a different genome. Here's why. </span> <span class="attribution"><span class="source">from www.shutterstock.com.au</span></span></figcaption></figure><p>We’ve probably all heard of mitochondria, and we may even remember learning in school that they are the “powerhouses of the cell” – but what does that actually mean, and how did they evolve? To answer this question, we have to go back about two billion years to a time when none of the complexity of life as we see it today existed. </p>
<h2>Where did mitochondria come from?</h2>
<p>Our primordial ancestor was a simple single-celled creature, living in a long-term rut of evolutionary stagnation. Then something dramatic happened – an event that would literally breathe life into the eventual evolution of complex organisms. One of the cells engulfed another and enslaved it as a perpetual source of energy for its host. </p>
<p>The increase in available energy to the cell powered the formation of more complex organisms with multiple cells, eyes, and brains. Slowly, the two species became intertwined – sharing some of their DNA and delegating specific cellular tasks – until eventually they became firmly hardwired to each other to form the most intimate of biological relationships. Two separate species became one. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/viewpoints-the-promise-and-perils-of-three-parent-ivf-18402">Viewpoints: the promise and perils of three-parent IVF</a>
</strong>
</em>
</p>
<hr>
<p>These energy slaves are the mitochondria, and there are hundreds or even thousands of them inside every one of your cells (with the exception of red blood cells) and in every other human alive. They still resemble their bacterial origin in appearance, but we can no longer exist without them, nor they without us. The evolutionary explosion powered by mitochondria is evident by the fact they are found in every complex multicellular organism that has ever existed, from giraffes to palm trees, mushrooms and dinosaurs. </p>
<p>As vestiges of their ancient origin, mitochondria still have their own genome (although some of their DNA has been transferred to our genome). It’s alien in appearance and composition when compared with our own nuclear genome (the DNA inside each of your cell’s nuclei that contains about 20,000 genes). In fact, our nuclear genome shares more in common with that of a sea sponge than with the mitochondrial genome inside our own cells. </p>
<p>Unlike the nuclear genome, the mitochondrial genome is small (containing just 37 genes), circular, and uses a different DNA code. The mitochondrial genome slinks its way across generations by stowing away within mitochondria harboured in each egg, and as such, is passed down from the mother only. This is different to the nuclear genome, half of which is inherited from your father and the other half from your mother. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/do-you-share-more-genes-with-your-mother-or-your-father-50076">Do you share more genes with your mother or your father?</a>
</strong>
</em>
</p>
<hr>
<h2>What do the mitochondria do?</h2>
<p>The mitochondrial genome is vital for the mitochondria’s main role: burning the calories we eat with the oxygen we breathe to generate the energy to power all of our biological processes. But this amazing source of energy is not without its cost.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186947/original/file-20170921-10635-rk7evh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The mitochondrial genome is passed down from the mother only.</span>
<span class="attribution"><span class="source">Natalya Zaritskaya/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Like any powerhouse, mitochondria produce toxic byproducts. Free radicals (highly reactive oxygen molecules with an odd number of electrons that can cause ageing and health problems) can be created by accidents that happen during energy production. </p>
<p>So in essence, mitochondria power <em>and</em> imperil our cells.</p>
<p>Because the mitochondrial genome is in close proximity to the source of free radicals, it’s more susceptible to their damaging effects. And the mitochondrial genome undergoes replication thousands of times more than the nuclear genome, simply because you have so many in each cell. Making copies of copies introduces mistakes. </p>
<p>A combination of these two effects results in the mitochondrial genome mutating up to 50 times faster than the nuclear genome, which is meanwhile kept safely in the nucleus. These mutations can be passed down to maternal offspring, causing devastating metabolic disorders in the next generation.</p>
<h2>What happens when something goes wrong?</h2>
<p>Only as recently as 1988 was the first disease caused by such a mutation in the mitochondrial genome identified. Now, we know about many such disorders, called mitochondrial diseases, which can be traced to mutations in the mitochondrial genome. These diseases can manifest at any age and result in a wide range of symptoms including hearing loss, blindness, muscle wasting, stroke-like episodes, seizures, and organ failure.</p>
<p>These diseases are currently incurable. But <a href="https://academic.oup.com/brain/article/139/6/1633/1754057/Emerging-therapies-for-mitochondrial-disorders">multiple lines of investigation</a> are currently underway to treat and <a href="https://theconversation.com/safety-in-numbers-how-three-parents-can-beat-genetic-diseases-2524">prevent transmission to subsequent generations</a>.</p>
<p>Despite this, during life, it’s inevitable that mutations will occur in the mitochondrial genome in an individual’s neurons, muscle, and all other cells. <a href="http://www.nature.com/ng/journal/v38/n5/full/ng1769.html?foxtrotcallback=true">Compelling work</a> now <a href="https://www.ncbi.nlm.nih.gov/pubmed/26014345">suggests</a> that the accumulation of these mistakes may contribute to the progressive nature of late-onset degenerative diseases such as Alzheimer’s and Parkinson’s. </p>
<p>The health of this seemingly alien genome is inextricably linked to that of our own bodies. As we come to grips with mitochondria’s importance in disease, we continue to uncover the intimate secrets of a two-billion-year relationship that has given complex life to the planet.</p><img src="https://counter.theconversation.com/content/83106/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steven Zuryn receives funding from the National Health and Medical Research Council and the Stafford Fox Medical Research Foundation. </span></em></p>To explain why we have a mitochondria, we have to go back about two billion years to a time when none of the complexity of life as we see it today existed.Steven Zuryn, Group Leader, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/822502017-08-28T20:08:30Z2017-08-28T20:08:30ZFrom the crime scene to the courtroom: the journey of a DNA sample<p>The O.J. Simpson murder trial in 1995 introduced DNA forensics to the public. The case collapsed, partly because the defence lawyers cast doubt on the validity of the evidence thanks to the inappropriate way the samples <a href="http://www.latimes.com/opinion/op-ed/la-oe-0618-morrison-scheck-oj-simpson-20140618-column.html">were handled</a>. </p>
<p>Things have changed since then. There are now safeguards in place to ensure the integrity of the chain of evidence. Laboratory protocols and procedures have also advanced. </p>
<p>By following a piece of evidence from the crime scene to the courtroom, we’ll explain just how DNA is studied in the lab and used in the modern legal system.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-forensic-science-2817">Explainer: Forensic science</a>
</strong>
</em>
</p>
<hr>
<h2>From the crime scene</h2>
<p>The DNA sample’s journey begins at the crime scene.</p>
<p>There are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4637504/#B63">several principles</a> that guide DNA evidence collection by the <a href="http://www.abc.net.au/news/2015-08-16/crime-scene-investigation-specialists-reveal-gritty-side-of-jobs/6681316">crime scene examiner</a>. In particular, the avoidance of contamination or DNA degradation, and ensuring the chain of custody. </p>
<p>The risk of contamination (from the collector or other evidence samples) is reduced by using sterile, disposable supplies. Degradation is minimised by drying samples before bagging. </p>
<p>Storing dried samples in <a href="https://www.mcscs.jus.gov.on.ca/english/centre_forensic/InformationforInvestigatorsSubmitters/HandbookofForensicEvidencefortheInvestigator/CFS_handbook.html">paper bags</a> rather than plastic, and maintaining samples at the proper temperature helps preserve the DNA and prevent microbial contamination. </p>
<p>It is also important to plan what to collect and how – sufficient material may be required for independent testing by the defence. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/183541/original/file-20170828-27540-5oq4kn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183541/original/file-20170828-27540-5oq4kn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183541/original/file-20170828-27540-5oq4kn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183541/original/file-20170828-27540-5oq4kn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183541/original/file-20170828-27540-5oq4kn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183541/original/file-20170828-27540-5oq4kn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183541/original/file-20170828-27540-5oq4kn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Police must ensure samples are not contaminated.</span>
<span class="attribution"><span class="source">James Hereward and Caitlin Curtis</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>To the lab</h2>
<p>When any sample arrives in a lab, the first step is to extract the DNA. </p>
<p>The blood samples analysed in the O.J. Simpson trial were typical of the time when large amounts of DNA were required to conduct testing. Today, small amounts of DNA, known as trace DNA, can be analysed from items such as cigarette butts, hair follicles, saliva, semen, and even <a href="http://www.bbc.com/news/world-us-canada-40855915">faeces</a>.</p>
<p>This is possible because of the invention of a method in the 1980s called the polymerase chain reaction or “<a href="https://www.khanacademy.org/science/biology/biotech-dna-technology/dna-sequencing-pcr-electrophoresis/a/polymerase-chain-reaction-pcr">PCR</a>”, which allows an individual strand of DNA to be replicated many times. This creates thousands of copies until there is enough DNA to conduct tests.</p>
<h2>Analysis begins</h2>
<p>The mainstay of modern DNA identification is <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3561883/">short tandem repeat</a> (STR) markers, which are small sections of DNA that vary by length (the number of repeats). </p>
<p>Multiple STR markers are used to create a DNA profile. They are tested using commercial kits that often incorporate a sex determination test (the <a href="https://link.springer.com/article/10.1007%2FBF01371335?LI=true">amelogenin</a> gene). </p>
<p><strong>Mitochondrial DNA</strong></p>
<p>Another method uses mitochondrial DNA.</p>
<p>Mitochondrial DNA tends to last longer than other types of DNA and is often relied on in cold cases. The sequence of mitochondrial DNA “letters” is passed down from mother to child (with the exception of rare mutations), so mothers and grandmothers share the same DNA sequence as their children (but fathers do not). </p>
<p>This makes mitochondrial DNA useful in identifying missing persons - the bones of Daniel Morcombe <a href="https://www.theguardian.com/world/2014/feb/12/daniel-morcombe-case-mothers-dna-matched-100-with-bone-sample">were identified this way</a>. </p>
<hr>
<p><em><strong>Read more</strong> <a href="https://theconversation.com/ned-kelly-remains-are-positively-identified-but-how-was-it-done-3174">Ned Kelly remains are positively identified … but how was it done?</a></em> </p>
<hr>
<p><strong>The Y chromosome</strong></p>
<p>The Y chromosome is present only in males and is passed from father to son. This makes Y chromosome STR markers a useful tool in situations such as <a href="http://www.kgw.com/news/crime/how-are-rape-kits-processed/449988969">sexual assault cases</a> where male and female DNA samples might be mixed and the male suspect’s identity needs to be established.</p>
<p>In the same way as mitochondrial markers, Y-markers can be used for identification through family matching. The process of <a href="http://www.latimes.com/local/lanow/la-me-familial-dna-20161023-snap-story.html">familial matching</a> in criminal investigations raises <a href="http://criminal.findlaw.com/criminal-rights/familial-dna-searches.html">privacy concerns</a> but is increasingly commonplace. </p>
<p>In one recent incident, it was suggested that the surname of a suspect was identified from records of male <a href="http://www.azcentral.com/story/news/local/phoenix/2016/11/30/how-forensic-genealogy-led-arrest-phoenix-canal-killer-case-bryan-patrick-miller-dna/94565410/">family members</a> in public genetic ancestry databases. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/183556/original/file-20170828-27807-fdmar0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183556/original/file-20170828-27807-fdmar0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183556/original/file-20170828-27807-fdmar0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183556/original/file-20170828-27807-fdmar0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183556/original/file-20170828-27807-fdmar0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183556/original/file-20170828-27807-fdmar0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183556/original/file-20170828-27807-fdmar0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tests often look for Y chromosome STR markers to establish identity.</span>
<span class="attribution"><span class="source">University of Michigan School of Natural Resources & Environment</span></span>
</figcaption>
</figure>
<h2>DNA databases and sample matching</h2>
<p>Australian law enforcement uses the National Criminal Investigation DNA Database (<a href="https://www.acic.gov.au/our-services/biometric-matching/national-criminal-investigation-dna-database">NCIDD</a>), which is managed by the Australian Criminal Intelligence Commission.</p>
<p>The more records added to the database, the greater the odds of making an accidental match. This is because the number of potential matches increases.</p>
<p>To reduce the risk of false “hits”, genetic profiles can be made more complex. Increasing the number of STRs in each profile reduces the risk of a spurious match because the probability of a match (at 20 markers, for example) is estimated by multiplying the probabilities of each STR marker. </p>
<p>The Australian system originally used nine STR’s and a sex-determination gene. In 2013 this was increased to <a href="https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwjpjLfGjuLVAhUHnpQKHZ5MAuUQFghIMAQ&url=http%3A%2F%2Fwww.anzpaa.org.au%2FArticleDocuments%2F218%2FDNA%2520Profiling%2520Success%2520Rates%2520ISFG%25202013.pdf.aspx&usg=AFQjCNGQpqd6ZYZrMyKkhZS4KYWsLsmvZA">18 core markers</a>.</p>
<p>Internationally, there are moves towards a standard set of 24 markers (such as <a href="https://www.thermofisher.com/order/catalog/product/4476135">GlobalFiler</a>). With this many markers, the odds of two people having the same profile (twins excepted) are incredibly small. This makes an STR profile a powerful way to exclude suspects as well as making matches. </p>
<h2>In the courtroom</h2>
<p>Modern DNA forensic methods are powerful and sensitive, but great care must be taken to prevent miscarriages of justice. </p>
<p>It is difficult for people to comprehend probabilities like one in a quadrillion, and the presentation of such numbers in court can become prejudicial.</p>
<p>In the case of <em><a href="http://eresources.hcourt.gov.au/showCase/2012/HCA/15">Aytugrul v the Queen</a></em>, DNA evidence was presented as an exclusion percentage of 99.9, and the defence argued that this would indicate certainty of guilt to the jury. </p>
<p>Although the High Court of Australia ultimately allowed the DNA evidence presentation in <em>Aytugrul v the Queen</em>, survey data suggest that the statistical presentation of genetic evidence may affect how it is understood and <a href="http://www.tandfonline.com/doi/abs/10.1080/00450618.2014.992472">used by a jury</a>.</p>
<p>Such issues have lead to <a href="https://www.justice.gov/opa/pr/justice-department-issues-draft-guidance-regarding-expert-testimony-and-lab-reports-forensic">guidelines</a> by the US Department of Justice, among other justice groups, for the language used in forensic testimony and reports.</p>
<p>There’s also a risk that contamination might implicate an innocent person. For that reason, DNA evidence is best used in support of other types of evidence. </p>
<p>In the case of <em><a href="http://guides.sl.nsw.gov.au/c.php?g=671792&p=4729488">R v Jama</a></em>, DNA evidence was the sole basis of the rape case. Only after <a href="http://www.aic.gov.au/media_library/publications/tandi_pdf/tandi506.pdf">16 months’</a> imprisonment was it revealed that the sample taken by the doctor was probably contaminated.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/183562/original/file-20170828-27547-1kkhxr7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183562/original/file-20170828-27547-1kkhxr7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=500&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183562/original/file-20170828-27547-1kkhxr7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=500&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183562/original/file-20170828-27547-1kkhxr7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=500&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183562/original/file-20170828-27547-1kkhxr7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=628&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183562/original/file-20170828-27547-1kkhxr7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=628&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183562/original/file-20170828-27547-1kkhxr7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=628&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">DNA can now be turned into digital data by massively parallel sequencing machines.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Forensics in the future</h2>
<p>DNA forensics will continue to evolve.</p>
<p>Take a genetic test that can predict <a href="http://www.fsigenetics.com/article/S1872-4973(12)00181-0/abstract">eye and hair colour</a>: this test examines (or “genotypes”) 24 single letter DNA variants. These are analysed with a statistical model that provides probabilities for hair and eye colour based on a large database that links DNA variants to appearance.</p>
<p>Understanding how DNA is linked to <a href="https://www.newscientist.com/article/mg22129613-600-genetic-mugshot-recreates-faces-from-nothing-but-dna/">facial features</a> has even led to the creation of DNA-based <a href="https://snapshot.parabon-nanolabs.com/">mugshots</a>. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3238019/">“Massively parallel” sequencing</a> machines are also a significant advance. These can turn the approximately 3.2 billion DNA “letters” of the human genome into digital information in a matter of hours. </p>
<p>This opens up all of the information contained in our genetic code to law enforcement. For example, some researchers claim it’s possible to <a href="http://www.reuters.com/article/us-dna-suspects-age-idUSKCN0V31BQ">predict the age of a suspect from a blood sample</a> within a mean error margin of 3.8 years, based on methylation markers in the DNA, and this may be improved with the assistance of <a href="http://www.sciencedirect.com/science/article/pii/S1872497317300388">machine learning</a>. </p>
<p>The more we understand the link between appearance and DNA, the better its predictive power will be. It’s tempting to speculate how the O.J. Simpson trial may have turned out with modern forensic DNA protocols and technology.</p><img src="https://counter.theconversation.com/content/82250/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Genetic evidence has become a critical aspect of modern criminal investigations. What are the methods and approaches used in present-day DNA forensics?Caitlin Curtis, Honorary Research Fellow, The University of QueenslandJames Hereward, PostDoc Ecological and Evolutionary Genetics, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/759572017-04-12T18:01:33Z2017-04-12T18:01:33ZFishing for DNA: Free-floating eDNA identifies presence and abundance of ocean life<figure><img src="https://images.theconversation.com/files/164726/original/image-20170410-31882-15i73ly.jpg?ixlib=rb-1.1.0&rect=12%2C84%2C813%2C449&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fish leave bits of DNA behind that researchers can collect.</span> <span class="attribution"><span class="source">Mark Stoeckle/Diane Rome Peebles images</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Ocean life is largely hidden from view. Monitoring what lives where is costly – typically requiring big boats, big nets, skilled personnel and plenty of time. An emerging technology using what’s called environmental DNA gets around some of those limitations, providing a quick, affordable way to figure out what’s present beneath the water’s surface. </p>
<p>Fish and other animals shed DNA into the water, in the form of cells, secretions or excreta. About 10 years ago, researchers in Europe first demonstrated that small volumes of pond water contained enough <a href="https://dx.doi.org/10.1098/rsbl.2008.0118">free-floating DNA to detect resident animals</a>.</p>
<p>Researchers have <a href="https://dx.doi.org/10.1371/journal.pone.0023398">subsequently</a> <a href="https://dx.doi.org/10.1371/journal.pone.0035868">looked for</a> <a href="https://doi.org/10.1016/j.biocon.2014.11.025">aquatic eDNA</a> <a href="https://doi.org/10.1111/1755-0998.12433">in multiple</a> <a href="https://doi.org/10.1016/j.biocon.2014.11.020">freshwater systems</a>, and <a href="https://dx.doi.org/10.1371/journal.pone.0041732">more recently</a> in <a href="https://dx.doi.org/10.1371/journal.pone.0041781">vastly larger</a> and <a href="https://dx.doi.org/10.1371/journal.pone.0086175">more complex</a> <a href="https://doi.org/10.1111/mec.13481">marine</a> <a href="https://dx.doi.org/10.1371/journal.pone.0165252">environments</a>. While the principle of aquatic eDNA is well-established, we’re just beginning to explore its potential for detecting fish and their abundance in particular marine settings. The technology promises many practical and scientific applications, from helping set sustainable fish quotas and evaluating protections for endangered species to assessing the impacts of offshore wind farms.</p>
<h2>Who’s in the Hudson, when?</h2>
<p><a href="https://doi.org/10.1371/journal.pone.0175186">In our new study</a>, <a href="https://phe.rockefeller.edu/barcode/blog/nycnj-aquatic-vertebrate-edna-project/">my colleagues and I</a> tested how well aquatic eDNA could detect fish in the Hudson River estuary surrounding New York City. Despite being the most heavily urbanized estuary in North America, water quality has <a href="http://www.nyc.gov/html/dep/pdf/hwqs2011.pdf">improved dramatically</a> over the past decades, and the estuary has partly recovered its role as essential habitat for many fish species. The improved health of local waters is highlighted by the now <a href="https://www.nytimes.com/2016/07/10/nyregion/the-great-new-york-whale-census.html">regular fall appearance of humpback whales</a> feeding on large schools of <a href="http://discovermagazine.com/2001/sep/featfish">Atlantic menhaden</a> at the borders of New York harbor, within site of the Empire State Building. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=751&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=751&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=751&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164947/original/image-20170411-26730-1vpceyd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Preparing to hurl the collecting bucket into the river.</span>
<span class="attribution"><span class="source">Mark Stoeckle</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our study is the first recording of spring migration of ocean fish by conducting DNA tests on water samples. We collected one liter (about a quart) water samples weekly at two city sites from January to July 2016. Because the Manhattan shoreline is armored and elevated, we tossed a bucket on a rope into the water. Wintertime samples had little or no fish eDNA. Beginning in April there was a steady increase in fish detected, with about 10 to 15 species per sample by early summer. The eDNA findings largely matched our existing knowledge of fish movements, hard won from decades of traditional seining surveys.</p>
<iframe src="https://datawrapper.dwcdn.net/4bGEP/4/" frameborder="0" allowtransparency="true" allowfullscreen="allowfullscreen" webkitallowfullscreen="webkitallowfullscreen" mozallowfullscreen="mozallowfullscreen" oallowfullscreen="oallowfullscreen" msallowfullscreen="msallowfullscreen" width="100%" height="500"></iframe>
<p>Our results demonstrate the “Goldilocks” quality of aquatic eDNA – it seems to last just the right amount of time to be useful. If it disappeared too quickly, we wouldn’t be able to detect it. If it lasted for too long, we wouldn’t detect seasonal differences and would likely find DNAs of many freshwater and open ocean species as well as those of local estuary fish. Research suggests <a href="https://doi.org/10.1021/acs.est.6b03114">DNA decays over hours to days</a>, depending on temperature, currents and so on.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=734&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=734&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=734&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=922&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=922&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164948/original/image-20170411-26733-15fdz4w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=922&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fish identified via eDNA in one day’s sample from New York City’s East River.</span>
<span class="attribution"><span class="source">New York State Department of Environmental Conservation: alewife (herring species), striped bass, American eel, mummichog; Massachusetts Department of Fish and Game: black sea bass, bluefish, Atlantic silverside; New Jersey Scuba Diving Association: oyster toadfish; Diane Rome Peeples: Atlantic menhaden, Tautog, Bay anchovy; H. Gervais: conger eel.</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Altogether, we obtained eDNAs matching 42 local marine fish species, including most (80 percent) of the locally abundant or common species. In addition, of species that we detected, abundant or common species were more frequently observed than were locally uncommon ones. That the species eDNA detected matched traditional observations of locally common fish in terms of abundance is good news for the method – it supports eDNA as an index of fish numbers. We expect we’ll eventually be able to detect all local species – by collecting larger volumes, at additional sites in the estuary and at different depths. </p>
<p>In addition to local marine species, we also found locally rare or absent species in a few samples. Most were fish we eat – Nile tilapia, Atlantic salmon, European sea bass (“branzino”). We speculate these came from wastewater – even though the Hudson is cleaner, <a href="https://www.riverkeeper.org/wp-content/uploads/2015/06/Riverkeeper_WQReport_2015_Final.pdf">sewage contamination persists</a>. If that is how the DNA got into the estuary in this case, then it might be possible to determine if a community is consuming protected species by testing its wastewater. The remaining exotics we found were freshwater species, surprisingly few given the large, daily freshwater inflows into the saltwater estuary from the Hudson watershed. </p>
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<a href="https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164945/original/image-20170411-26730-11e9w3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Filtering the estuary water back in the lab.</span>
<span class="attribution"><span class="source">Mark Stoeckle</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Analyzing the naked DNA</h2>
<p>Our protocol uses methods and equipment standard in a molecular biology laboratory, and follows the same procedures used to analyze human microbiomes, for example.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164946/original/image-20170411-26741-1ns4wwu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">eDNA and other debris left on the filter after the estuary water passed through.</span>
<span class="attribution"><span class="source">Mark Stoeckle</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>After collection, we run water samples through a small pore size (0.45 micron) filter that traps suspended material, including cells and cell fragments. We extract DNA from the filter, and amplify it using polymerase chain reaction (PCR). PCR is like “xeroxing” a particular DNA sequence, producing enough copies so that it can easily be analyzed.</p>
<p>We targeted mitochondrial DNA – the genetic material within the mitochondria, the organelle that generates the cell’s energy. Mitochondrial DNA is present in much higher concentrations than nuclear DNA, and so easier to detect. It also has regions that are the same in all vertebrates, which makes it easier for us to amplify multiple species.</p>
<p>We tagged each amplified sample, pooled the samples and sent them for next-generation sequencing. Rockefeller University scientist and co-author Zachary Charlop-Powers created the bioinformatic pipeline that assesses sequence quality and generates a list of the unique sequences and “read numbers” in each sample. That’s how many times we detected each unique sequence.</p>
<p>To identify species, each unique sequence is compared to those in the public database GenBank. Our results are consistent with read number being proportional to fish numbers, but more work is needed on the precise relationship of eDNA and fish abundance. For example, some fish may shed more DNA than others. The effects of fish mortality, water temperature, eggs and larval fish versus adult forms could also be at play.</p>
<p>Just like in television crime shows, eDNA identification relies on a comprehensive and accurate database. <a href="https://doi.org/10.1371/journal.pone.0175186">In a pilot study</a>, we identified local species that were missing from the GenBank database, or had incomplete or mismatched sequences. To improve identifications, we sequenced 31 specimens representing 18 species from scientific collections at Monmouth University, and from bait stores and fish markets. This work was largely done by student researcher and co-author Lyubov Soboleva, a senior at John Bowne High School in New York City. We deposited these new sequences in GenBank, boosting the database’s coverage to about 80 percent of our local species. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=473&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=473&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=473&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=594&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=594&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164982/original/image-20170412-26730-m2nkq4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=594&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Study’s collection sites in Manhattan.</span>
<span class="attribution"><span class="source">Mark Stoeckle</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We focused on fish and other vertebrates. Other research groups have applied an aquatic eDNA approach to invertebrates. In principle, the technique could assess the diversity of all animal, plant and microbial life in a particular habitat. In addition to detecting aquatic animals, eDNA reflects terrestrial animals in nearby watersheds. In our study, the commonest wild animal detected in New York City waters was the brown rat, a common urban denizen.</p>
<p>Future studies might employ autonomous vehicles to routinely sample remote and deep sites, helping us to better understand and manage the diversity of ocean life.</p><img src="https://counter.theconversation.com/content/75957/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Stoeckle receives funding from Monmouth University-Rockefeller University Marine Science Policy Initiative (MURU). </span></em></p>Animals shed bits of DNA as they go about their lives. A new study of the Hudson River estuary tracked spring migration of ocean fish by collecting water samples and seeing whose DNA was present when.Mark Stoeckle, Senior Research Associate in the Program for the Human Environment, The Rockefeller UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/671322016-11-18T03:34:09Z2016-11-18T03:34:09ZThe next frontier in reproductive tourism? Genetic modification<figure><img src="https://images.theconversation.com/files/144124/original/image-20161101-24460-1pylff6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Human oocyte in vitro fertilization.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/zeissmicro/27771482282">Ziess Microscopy/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The birth of the first baby born using a technique <a href="https://www.newscientist.com/article/2107219-exclusive-worlds-first-baby-born-with-new-3-parent-technique">called mitochondrial replacement, which uses DNA from three people</a> to “correct” an inherited genetic mutation, was announced in September 2016. </p>
<p>Mitochondrial replacement or donation allows women who carry mitochondrial diseases to avoid passing them on to their child. These diseases can range from mild to life-threatening. No therapies exist and only a few drugs are available to treat them.</p>
<p>There are no international rules regulating this technique. Just one country, the United Kingdom, explicitly <a href="http://www.legislation.gov.uk/uksi/2015/572/contents/made">regulates the procedure</a>. It’s a similar situation with other assisted reproductive techniques. Some countries permit these techniques and others don’t. </p>
<p>I study the intended and unintended consequences of regulating, prohibiting or authorizing the use of new technologies. One of these unintended consequences is “medical tourism,” where people travel from their home countries to places where practices such as commercial surrogacy or embryo selection are allowed. </p>
<p>Medical tourism for assisted reproductive technologies raises a host of legal and ethical questions. While new reproductive technologies, like mitochondrial replacement, promise to bring significant benefits, the absence of regulations means that some of these questions, including those related to safety and risks are unanswered, even as people are starting to use them. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/144123/original/image-20161101-14771-1fuj1bn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/144123/original/image-20161101-14771-1fuj1bn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/144123/original/image-20161101-14771-1fuj1bn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/144123/original/image-20161101-14771-1fuj1bn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/144123/original/image-20161101-14771-1fuj1bn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/144123/original/image-20161101-14771-1fuj1bn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/144123/original/image-20161101-14771-1fuj1bn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mitochondria power our cells.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-425512399/stock-photo-mitochondrium-3d-rendering-microbiology-illustration.html?src=TrjF1GC8FGuEZ0mQ-utOwA-3-61">Mitochondrium image via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<h2>How does mitochondrial replacement work?</h2>
<p>We each inherit our mitochondria, which provide the energy that our cells need to function and the tiny fraction of DNA contained in it, only from our mothers. Some of that mitochondrial DNA might be defective, carrying mutations or errors that might lead to mitochondrial diseases.</p>
<p>The mother of the baby born using this technique carried one of these diseases. The disease, known as <a href="https://ghr.nlm.nih.gov/condition/leigh-syndrome#genes">Leigh Syndrome</a>, is a neurological disorder that typically leads to death during childhood. Before having this baby, the couple had two children who died as a result of the disease. </p>
<p>Mitochondrial replacement is done in a lab, as part of in vitro fertilization. It works by “substituting” the defective mitochondria of the mother’s egg with healthy mitochondria obtained from a donor. The child is genetically related to the mother, but has the donor’s mitochondrial DNA. </p>
<p>It involves three germ cells: an egg from the mother, an egg from a healthy donor and the sperm from the father. While the term “three-parent” child is often used in news <a href="http://www.nytimes.com/2016/09/28/health/birth-of-3-parent-baby-a-success-for-controversial-procedure.html?_r=0">stories</a>, it is a highly controversial one. </p>
<p>To some, the tiny fraction of DNA contained in a mitochondria provided by a donor is not sufficient to make the donor a “second mother.” The U.K., the only country that has regulated the technique, takes this position. Ultimately, the DNA replaced is a tiny fraction of a person’s genes, and it is unrelated to the characteristics that we associate with genetic kinship.</p>
<p>There is some discussion as to whether mitochondrial replacement is a so-called “germ line modification,” a genetic modification that can be inherited. Many <a href="http://www.nature.com/news/where-in-the-world-could-the-first-crispr-baby-be-born-1.18542">countries</a>, including the U.K., have either banned or taken a serious stance on technologies that could alter germ cells and cause inherited changes that can affect future generations. But a great number of countries, including Japan and India, have ambiguous or unenforceable regulations about germline modification.</p>
<p>Mitochondrial replacement results in a germline change, but that change is passed to future generations only if the child is a girl. She would pass the donor’s mitochondrial DNA to her offspring, and in turn her female descendants will pass it to their children. If the child is a boy, he wouldn’t pass the mitochondrial DNA on to his offspring. </p>
<p>Because the mitochondrial modification is only heritable in girls, the U.S. National Academies of Science recently recommended that use of this technique be <a href="https://www.nationalacademies.org/hmd/Reports/2016/Mitochondrial-Replacement-Techniques.aspx">limited to male embryos</a>, in which the change is not inheritable. The U.K. considered but then rejected this approach.</p>
<h2>A thorny ethical and regulatory debate</h2>
<p>In the U.S., the FDA claimed jurisdiction to regulate mitochondrial replacement but then halted further discussions. A rider included in the <a href="https://www.congress.gov/bill/114th-congress/house-bill/2029/text">2016 Congressional Appropriations Act</a> precludes the FDA from considering mitochondrial replacement.</p>
<p>While the technique has been given the green light in the U.K., the nation’s Human Fertilisation and Embryology Authority is gathering more <a href="http://www.hfea.gov.uk/10363.html">safety-related information</a> before granting the first licenses for mitochondrial replacement to clinics.</p>
<p>Experts have predicted that once the authority starts granting authorization, people seeking mitochondrial replacement would go to the U.K. </p>
<p>At the moment, with no global standard dictating the use of mitochondrial replacement, couples (and experts willing to use these technologies) are going to countries where the procedure is allowed. </p>
<p>This has happened with other technologies such as embryo selection and commercial surrogacy, with patients traveling abroad to seek out assisted reproduction services or technologies that are either prohibited, unavailable, of lower quality or more expensive in their own countries.</p>
<p>The <a href="https://www.newscientist.com/article/2107219-exclusive-worlds-first-baby-born-with-new-3-parent-technique/">first documented case</a> of successful mitochondrial replacement involved U.S. physicians assisting a Jordanian couple in Mexico. Further reports of the use of mitochondrial replacement in <a href="https://www.newscientist.com/article/2108549-exclusive-3-parent-baby-method-already-used-for-infertility/">Ukraine</a> and <a href="http://www.nature.com/news/reports-of-three-parent-babies-multiply-1.20849">China</a> have followed. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/146461/original/image-20161117-18108-1di8hjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/146461/original/image-20161117-18108-1di8hjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/146461/original/image-20161117-18108-1di8hjo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/146461/original/image-20161117-18108-1di8hjo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/146461/original/image-20161117-18108-1di8hjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/146461/original/image-20161117-18108-1di8hjo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/146461/original/image-20161117-18108-1di8hjo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In this Nov. 3, 2015 photo, a newborn baby is transferred to an ambulance at the Akanksha Clinic, one of the most organized clinics in the surrogacy business, in Anand, India.</span>
<span class="attribution"><span class="source">Allison Joyce/AP</span></span>
</figcaption>
</figure>
<p>The increasing trend of medical tourism has been followed by sporadic <a href="http://www.telegraph.co.uk/news/2016/04/14/baby-gammy-was-not-abandoned-in-thailand-court-rules/">scandals</a> and waves of tighter regulations in countries such as <a href="http://www.cnn.com/2016/09/08/asia/india-surrogacy-laws/">India</a>, <a href="http://www.nytimes.com/2016/05/03/world/asia/nepal-bans-surrogacy-leaving-couples-with-few-low-cost-options.html?_r=0">Nepal</a> and <a href="http://www.bbc.com/news/world-asia-31546717">Thailand</a>, which have been leading destinations of couples seeking assisted reproduction services.</p>
<p>Intended parents and children born with the help of assisted reproduction outside of their home countries have faced problems related to family ties, citizenship and their relationship with donors – especially with the use of <a href="http://scholarship.law.berkeley.edu/cgi/viewcontent.cgi?article=1420&context=bjil">commercial surrogacy</a>.</p>
<p>Mitochondrial replacement and new gene editing technologies add further questions related to the safety and long-term effects of these procedures.</p>
<h2>Gene modification complicates reproductive tourism</h2>
<p>Mitochondrial replacement and technologies such as gene-editing with the use of <a href="http://www.nytimes.com/2015/12/18/opinion/a-pause-to-weigh-risks-of-gene-editing.html">CRISPR-CAS9</a> that create germline modifications are relatively new. Many of the legal and ethical questions they raise have yet to be answered.</p>
<p>What if the children born as a result of these techniques suffer unknown adverse effects? And could these technologies affect the way in which we think about identity, kinship and family ties in general? One technique to replace mutated mitochondria involves the creation of embryos that will be later disposed. How should the use and disposal of embryos be regulated? What about the interests of the egg donors? Should they be paid? </p>
<p>Some of these problems could be avoided through a solid regulatory system in the U.S. and other countries. But as long as patients continue to seek medical treatments in “havens” for ethically dubious or risky procedures, many of these problems will persist. </p>
<p>Regulatory authorities around the world are <a href="http://nationalacademies.org/gene-editing/consensus-study/index.htm">debating</a> how to better regulate these genetic modification technologies. Governments need to start considering not only the ethical and safety effects of their choices but also how these choices drive medical tourism.</p><img src="https://counter.theconversation.com/content/67132/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rosa Castro does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Medical tourism for assisted reproductive technologies raises a host of legal and ethical questions.Rosa Castro, Postdoctoral Associate in Science and Society, Duke UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/573592016-04-15T00:27:41Z2016-04-15T00:27:41ZMutant malaria parasites resistant to antimalarial Atovaquone cannot spread: new research<figure><img src="https://images.theconversation.com/files/117662/original/image-20160406-29002-xwldve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists found that malaria parasites resistant to antimalarial Atovaquone cannot survive inside their mosquito host. </span> <span class="attribution"><span class="source">Anest/www.shutterstock.com</span></span></figcaption></figure><p>Resistance to a commonly used antimalarial medication, Atovaquone, can’t spread to the general human population, new research suggests. </p>
<p>This is significant as scientists have been racing against malaria parasites’ rapid resistance to various antimalarial medications. </p>
<p>Resistance to antimalarial drugs hinders effective treatment of malaria, a life-threatening mosquito-borne infectious disease of which almost half of the world’s population (3.2 billion) are at risk of contracting. </p>
<p>An international team of researchers led by scientists from Eijkman Institute and University of Melbourne published the research today in <a href="http://science.sciencemag.org/content/352/6283/349">Science</a>. </p>
<p>The research shows that Atovaquone, a component of an effective antimalarial drug Malarone, interrupts the life cycle of resistant parasites in the mosquito phase.</p>
<p>“Drug resistance will not spread [to other patients] because mosquitoes will not be able to spread [the resistant strain]. This shows that Atovaquone is a safe drug,” co-principal investigator of the research, Professor Sangkot Marzuki, molecular biologist at the Eijkman Institute for molecular biology in Jakarta said. </p>
<p>Senior research officer from the Burnett Institute Paul Gilson, who was not involved in the research, said the findings show an “important breakthough” in malaria treatment. </p>
<p>“The big picture is that Atovaquone, once thought of as a second rate drug because parasites can easily become resistant to it, might be extremely effective at stopping malaria transmission and could therefore be important for disease eradication,” he said. </p>
<p>Like other antimalarials, Atovaquone is prone to resistance. The research findings debunked the assumption that resistance to Atovaquone will spread as it has with other antimalarials such as Artemisinin.</p>
<p>Commenting on the research, James McCarthy, professor of infectious diseases at Queensland Institute of Medical Research, who was not involved in the study said: “this suggests that the drug may be very useful in helping stop the spread of Artemisinin resistant parasites”. </p>
<p>“This [the research] would allow us to think about using Atovaquone to try to stop Artemisinin-resistant parasites from spreading because they would still be sensitive to Atovaquone,” Co-principal investigator Professor Geoffrey McFadden from University of Melbourne said. </p>
<p>Currently, Artemisinin-resistant malaria parasites have been discovered in the greater Mekong Delta and Indonesia. “If it gets away from there it then could become global,” Professor McFadden said.</p>
<p>Professor Marzuki said the findings are “important for future research on drug development” to treat not only malaria but also other parasitic diseases. </p>
<p>Malaria parasites have two life cycles: first, in their mammalian hosts, such as mice or humans; second, in their mosquito hosts. </p>
<p>The research shows that some malaria parasites developed a genetic mutation that protected them against Atovaquone in early life inside their mammalian hosts. But the mutation eventually killed the parasites in the mosquito life phase by stopping production of an essential type of energy as they grew. </p>
<p>Professor McFadden called it a “genetic trap”. </p>
<p>The research shows that Atovaquone can stop the life cycle of the resistant parasites, stopping them from spreading in the field, because it targets a protein called cytochrome b. </p>
<p>This protein, located inside the parasite’s cell – specifically in the mitochondria – is essential for the cells of the parasite to breath and release energy. </p>
<p>“The research shows that the target molecule of the drug is very important for the survival of the parasite in mosquitoes,” Professors Marzuki said. “Therefore, it’s a good target for future drug development for malaria and other parasitic diseases,” he added.</p>
<p>Professor Marzuki said using mice models, the team of researchers looked into how the parasites mutate inside their mammalian hosts and become resistant to the drug. The researchers isolated resistant mutants by periodically exposing parasites that are infecting mice with dosages of Atovaquone that would not kill the parasites entirely.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/118521/original/image-20160413-23623-5ri33o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/118521/original/image-20160413-23623-5ri33o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118521/original/image-20160413-23623-5ri33o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118521/original/image-20160413-23623-5ri33o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118521/original/image-20160413-23623-5ri33o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118521/original/image-20160413-23623-5ri33o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118521/original/image-20160413-23623-5ri33o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Malaria parasite.</span>
<span class="attribution"><span class="source">Courtesy of University of Melbourne</span></span>
</figcaption>
</figure>
<p>Professor Marzuki said the resistant parasites show mutations in their mitochondrial-DNA that expresses the gene for cytochrome b. </p>
<p>Professor Marzuki said this mutant strain survives in the mammalian host perhaps because even though cytochrome b could not function well in this strain, malaria parasites only need low respiratory activity when living in the red blood cells. </p>
<p>The researchers then tested the transmissibility of the resistant strain. They observed whether mice that had been bitten by mosquitoes that had bitten mice infected by the resistant strain will be infected too. The tests show the mosquitoes could not transmit the resistant strain to other mice.</p><img src="https://counter.theconversation.com/content/57359/count.gif" alt="The Conversation" width="1" height="1" />
Resistance to a commonly used antimalarial medication, Atovaquone, can’t spread to the general human population, a new research found.Prodita Sabarini, CEO/Publisher, The Conversation IndonesiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/500762015-11-19T19:05:48Z2015-11-19T19:05:48ZDo you share more genes with your mother or your father?<figure><img src="https://images.theconversation.com/files/102448/original/image-20151119-19367-w73ku0.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5279%2C3077&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">To whom is she more closely related?</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Many of your relatives probably have an answer to the question of whether you are more your mother or your father’s child. But the correct answer to the question is not as simple as it might seem.</p>
<p>Genetically, you actually carry more of your mother’s genes than your father’s. That’s because of little organelles that live within your cells, the <a href="http://www.nature.com/scitable/topicpage/mitochondria-14053590">mitochondria</a>, which you only receive from your mother.</p>
<p>Mitochondria are the energy-producing factories of the cell; without them, a cell would not be able to generate energy from food.</p>
<p>Mitochondria have an interesting history, as about 1.5-billion to 2-billion years ago they were free-living organisms. The ancestor of all mitochondria was a bacterium that was engulfed by another bacterium, but for one reason or another not digested, giving rise to the eukaryotes. The eukaryotes are basically all plants, animals and fungi, plus some rather weird organisms grouped together under <a href="http://www.encyclopedia.com/topic/Protista.aspx">Protista</a>.</p>
<p>Because of their evolutionary history as free-living bacteria, mitochondria have retained their own genome, called mitochondrial DNA, or mtDNA. Each cell contains many copies of mtDNA, as mitochondria freely replicate within the cell.</p>
<h2>The mother effect</h2>
<p>Tissues that require a lot of energy, such as your brain and your muscles, have cells packed with mitochondria. Because all mitochondria you received come from your mother only, you are technically more related to your mum than you are to your dad.</p>
<p>This is true for pretty much all animals. In plants and fungi too, mitochondria come from one parent only, although not necessarily from the mother.</p>
<p>Why do we have two different kinds of inheritance, one for nuclear genomes (nDNA) that combine parts of the mother and the father, and one for mitochondrial genomes, that excludes one parent completely?</p>
<p>The reason behind the evolution of so-called uniparental inheritance has long been a mystery among evolutionary biologists. One thing was clear: it better be for a good reason. </p>
<p>Mammalian males go through the bother of actually tagging the mitochondria in their sperm so that it is easier to destroy them after the <a href="http://www.sciencedirect.com/science/article/pii/S0167488913001092">egg has been fertilised</a>. In plants too, the mitochondria from one parent are actively destroyed, this time before <a href="http://link.springer.com/article/10.1007%2Fs10265-009-0306-9">fertilisation takes place</a>.</p>
<p>For decades <a href="http://www.sciencemag.org/content/281/5385/2003.full">the prevailing theory</a> explaining why mitochondria inherit uniparentally was the “conflict theory”.</p>
<p>The idea is that mtDNA replicates independently within the cell, so the number of copies increases over time. And the more copies there are, the more likely some will be transmitted to the daughter cell when that cell divides.</p>
<p>If all mtDNA comes from one parent only, then mtDNA within a cell are closely related to each other, as they are all clones. Hence, there is not much scope for competition, as copies of the mitochondrial genomes are basically competing with exact copies of themselves.</p>
<h2>Unhealthy competition</h2>
<p>But imagine what could happen if organelles were derived from both parents, the four grandparents, and so on ad infinitum. This would set the scene for a genetically variable population of organelles in every cell.</p>
<p>And this could be bad news as now different clonal lineages of mtDNA are competing with each other. The faster mtDNA replicates, the more copies it produces and the more likely it will spread to the next generation of cells.</p>
<p>Ultimately, the slower reproducing organelle lineage will be eliminated from the cell lineage. The smaller an organelle’s genome, the faster it can replicate. Thus, competition among organelles within cells selects for smaller genomes.</p>
<p>At some stage genomes will be so small that the function of the organelle is affected. Remember that the mitochondria produce the energy the cell needs, so when their genome size becomes very small, the organelles cease to function properly and the host cell suffers.</p>
<p>Interesting idea. But what is the evidence? Sadly, none.</p>
<h2>Cleaning the mix</h2>
<p>Recently a much simpler explanation was proposed: what if the simple mixing of mitochondrial lineages within the same cell is for some reason costly in itself?</p>
<p>This very simple assumption actually nicely explains the peculiar inheritance of <a href="http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1005112">mitochondria in theoretical models</a>. </p>
<p>But there is more. Mice that were experimentally constructed so that individuals carried two mitochondrial lineages were less active, ate less, were more stressed and were <a href="http://dx.doi.org/10.1016/j.cell.2012.09.004">cognitively impaired</a>. It seems carrying mitochondria from both your parents is bad for you.</p>
<p>So why is the question of whether you are more like your mum or dad so hard to answer? Because your genetic make-up is only part of the equation. Which genes are expressed is the other part. And apparently your dad has the upper hand when it comes to <a href="http://www.nature.com/ng/journal/v47/n4/full/ng.3222.html">which genes are expressed</a>.</p>
<p>So, you may look more like your dad but are more related to your mum after all. How is that for a simple answer?</p><img src="https://counter.theconversation.com/content/50076/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Madeleine Beekman receives funding from the Australian Research Council. She is affiliated with the International Union for the Study of Social Insects. </span></em></p>How many times do people make the comment about which parent a child takes after. So what does genetics say?Madeleine Beekman, Professor of Behavioural Ecology and ARC Future Fellow, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/184022013-09-20T02:28:07Z2013-09-20T02:28:07ZViewpoints: the promise and perils of three-parent IVF<figure><img src="https://images.theconversation.com/files/31637/original/sn7vcgm8-1379574080.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Three-parent IVF is about allowing women who carry genetic diseases in their mitochondria to avoid passing them on to their children.</span> <span class="attribution"><span class="source">Glenn/Flickr</span></span></figcaption></figure><p><em>Far from creating designer babies, <a href="https://theconversation.com/meet-mama-papa-and-mama-how-three-parent-ivf-works-15725">three-parent IVF</a> is about allowing women who carry genetic diseases in their mitochondria to avoid passing them on to their children. The process involves replacing the mitochondria from the ovum of a woman who has a mitochondrial disease with one from a healthy donor.</em></p>
<p><em>It’s controversial because it requires a third “parent”, a woman who can donate a healthy mitochondria. The technology is currently prohibited throughout the world although the UK government has <a href="http://www.bionews.org.uk/page_318118.asp">announced its intention</a> to draft proposals allowing it.</em> </p>
<p><em>The technology could work in two ways – transferring the chromosomes from the mother into an egg from a healthy donor that has only the mitochondria (with other chromosomes removed) before fertilisation. Or we could take all the chromosomes out of a fertilised egg and put them into a donor egg that, again, has been “emptied” apart from the mitochondria.</em></p>
<p><em>An article published in the journal Science today raises some potential concerns about the technique. Here, one of the authors of the paper, Damian Dowling explains some limitations of the process. And professor of mitochondrial genetics Justin St John responds.</em></p>
<hr>
<p><strong>Damian Dowling:</strong> Our article outlines key research findings, as well as the outcome of a public consultation by the UK Human Fertilisation and Embryology Authority (HFEA) into the safety and ethics of mitochondrial replacement, which is also known as mitochondrial replacement-assisted IVF, or popularly as three-parent IVF. We believe the technique holds exciting promise for prospective mothers suffering from mitochondrial disease. </p>
<p>We talk about a body of scientific literature that is highly pertinent to the technology, but has been by-and-large overlooked in the scientific and public forums of this debate.</p>
<p>People have different nuclear genomes (genetic make-up) and different mitochondrial DNA sequences (mtDNA or haplotypes). How we make energy is determined by how these genomes work in tandem with our mitochondrial haplotypes. Indeed, experimental research on model organisms, ranging from mice to insects, indicates that how the mitochondrial DNA interacts with the genome is tightly preserved by natural selection – nature’s quality control process. </p>
<p>This interaction (mito-nuclear) is salient to life as we know it because it regulates much of our energy production. </p>
<p>When researchers have used mitochondrial replacement-type techniques to mix-and-match different combinations of putatively healthy mitochondrial haplotypes and nuclear genomes, they have typically found that new mito-nuclear combinations change how organisms function – from altering development rates to cognitive ability, reproductive success to life expectancies. Sometimes, this is for the worse.</p>
<p>Mitochondrial replacement-assisted IVF can make novel combinations of mito-nuclear interaction in ways that normal sexual reproduction cannot. </p>
<p>Under normal conception, a copy of the mother’s nuclear genome is transmitted to her children in 100% of cases, along with her mitochondrial genotype. This gives natural selection the fuel to preserve optimally functioning mito-nuclear gene combinations, perpetually across generations.</p>
<p>In public discussions of this technology, mitochondria have been likened to batteries in a camera; it doesn’t matter what brand of battery you use, the camera will function well. The body of research we bring to the table suggests this analogy needs rethinking – the brand can affect the expression of many health-related traits.</p>
<p>We don’t want to block the transition of this technique to the clinic. But, we feel it’s our obligation to bring to the discussion the research that has been overlooked. This research should be considered by the authorities involved in bringing mitochondrial replacement-assisted IVF to the clinic, who should decide how relevant the results and principles highlighted in this literature are to humans. </p>
<p>Ultimately, it will be difficult to predict how relevant this all is to the human case.</p>
<p>Women who suffer mitochondrial disease and might benefit from this technique should at least have access to the full array of evidence. They should understand its potential implications, so they can make an informed choice that is right for them and their situation.</p>
<p>While we don’t claim that this is the whole solution, perhaps matching mitochondrial haplotypes of the donor and mother would make sense and should be explored further. This option has been discussed by the HFEA.</p>
<hr>
<p><strong>Justin St John:</strong> The authors of the Science piece mention that the research they are highlighting hasn’t been included in the public debate. It’s important to note that it has not been overlooked by the scientists working on the technology or the agencies involved.</p>
<p>For quite a while now, scientists have been trying to develop approaches to prevent future generations from inheriting diseases associated with the mitochondrial genome. </p>
<p>Proposed assisted reproductive technologies offer the opportunity to prevent these diseases from being passed from one generation to the next. This is a highly worthwhile pursuit, but there are a number of safety issues that still require further explanation. </p>
<p>The most important issue that Damian Dowling raises above is that research he is drawing attention to has been considered by the Human Fertilisation and Embryology Authority (HFEA). I have also previously argued this case in the scientific literature. </p>
<p>I would even go a step further and suggest the technology needs an all-round safety assessment, which is also the view of the UK’s Nuffield Council on Bioethics and the HFEA. It’s important to note that the HFEA is the only body in the world considering proceeding with the technology.</p>
<p>I want to be sure that there’s no accompanying mutated mitochondrial DNA introduced into the egg when the chromosomes from the mother are transferred into the donor egg. Modifications to this technology could prevent that.</p>
<p>I would also want to ensure that there are no other abnormal processes resulting from the transfer. It has previously been argued that the transfer of chromosomes from one egg to another could affect chromosomal gene expression patterns through <a href="https://theconversation.com/explainer-what-is-epigenetics-13877">epigenetic factors</a>.</p>
<p>To overcome these concerns, we are currently developing technologies to prevent the transfer of accompanying mitochondrial DNA. Once we have perfected this, we will test the outcomes in model systems.</p>
<p>That data would be available to the scientific community and the regulatory authorities, and it would enable informed decisions to be made about safety. </p>
<p>Sometimes, the public debate about complex science is simplified but that doesn’t mean that the science has been simplified, careless or rushing ahead heedless of negative consequences. It’s good that as we move closer to using this technology that the public debate becomes deeper, but that doesn’t mean that this depth is new in scientific circles. </p>
<p>We all seek to ensure that this area of research doesn’t generate another problem while solving one.</p><img src="https://counter.theconversation.com/content/18402/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Damian Dowling receives funding from the ARC.</span></em></p><p class="fine-print"><em><span>Justin St. John receives funding from NHMRC, which looks at mitochondrial mutations and previously held a grant from the UK MRC, which looked at cloned embryos and mitochondrial inheritance.</span></em></p>Far from creating designer babies, three-parent IVF is about allowing women who carry genetic diseases in their mitochondria to avoid passing them on to their children. The process involves replacing the…Damian Dowling, Senior Research Fellow , Monash UniversityJustin St. John, Professor and Director, Centre for Genetic Diseases, Monash Institute of Medical Research, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/158352013-07-22T05:37:23Z2013-07-22T05:37:23ZAlbert and Adam rewrite the story of human origins<figure><img src="https://images.theconversation.com/files/27757/original/783cnz7n-1374240339.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Looks like a modern human, but isn't. Evolution just got more complicated.</span> <span class="attribution"><span class="source">Erich Ferdinand</span></span></figcaption></figure><p>The DNA of Albert Perry may change the story of human origins. Perry was an African-American born into slavery in South Carolina. An analysis of the DNA of his descendants produced <a href="http://haplogroup-a.com/Ancient-Root-AJHG2013.pdf">results</a> that came as quite a surprise and have raised questions <a href="http://relocatingorigin.soc.srcf.net/?page_id=54">for geneticists</a> around the world.</p>
<p>It turns out that Perry carried a very different type of Y chromosome, never seen before. Every male has a Y chromosome, which is a piece of DNA inherited by sons from their fathers. But, unlike most DNA, the Y chromosome is not shuffled as it is passed down, and changes only slowly through mutation. Tracking these mutations allows scientists to create a genetic tree of fathers and sons going back through time.</p>
<p>As a man may have several sons or none, some branches of the genetic tree die out each generation, while others become more common. Going back through time it is therefore inevitable that all modern Y chromosomes must descend from from one man at some point in the past. He has become known as “Y-chromosomal Adam”.</p>
<p>This Adam was not the first man, or the only man, from his time to contribute to modern human DNA. It is just that, by chance, his Y chromosome was the only one to survive until today.</p>
<p>What is surprising about Perry’s Y chromosome is that it did not descend from Y-chromosomal Adam’s. Or rather that the established “Adam” has lost his title to a new “Adam”, further back in time, where Perry’s branch split from the tree (see figure). While the former-Adam is estimated to have lived around 202,000 years ago, the revised one is thought to be about 338,000 years old.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=529&fit=crop&dpr=1 600w, https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=529&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=529&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=665&fit=crop&dpr=1 754w, https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=665&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/27759/original/63s9qt7j-1374241733.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=665&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>To find where Perry’s Y chromosome may have come from, samples from around Africa were tested. Several more from Perry’s branch were found amongst the Mbo people of Cameroon.</p>
<p>So can this tell us anything about human origins? Central Africa contains Y chromosomes from both Perry’s branch and the former-Adam’s branch, while the rest of the world has only been shown to contain the former-Adam’s branch (with the exception of Perry himself). This suggests that our revised Adam may have lived in Central Africa.</p>
<p>The oldest-known “modern human” bones are from East Africa. But if Adam lived in Central Africa, does that mean that modern humans could have originated there? Again, it is hard to say. By looking further into the <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3218835/pdf/gb-2011-12-6-118.pdf">genetics of modern people</a>, the picture becomes even more complex. </p>
<p>It so happens that, just like the Y-chromosome is passed down only from father to son, there is a piece of DNA which sits in a different part of the cell called mitochondria, that is passed down only from mother to her children. Tracing back this DNA in a similar way, leads us to a “<a href="http://io9.com/5878996/how-mitochondrial-eve-connected-all-humanity-and-rewrote-human-evolution">Mitochondrial Eve</a>”, estimated to have lived about 190,000 years ago. Eve possibly lived in south-eastern Africa. But modern humans have DNA both from Adam and Eve.</p>
<p>Despite these apparent contradictions, it is possible that modern humans descended from a single localised population, and that geographical differences in diversity today are due to spread and extinction in the intervening years. But it could also be that many of <a href="https://theconversation.com/what-makes-us-human-genetics-culture-or-both-14505">the genetic and cultural ingredients</a> that produced modern humans existed in different parts of Africa, drifting and spreading until they came together and, by a mixture of luck and natural selection, became the combination that would out-compete their relatives to spread to the rest of the world. </p>
<p>One way or another, around 200,000 years ago, bones appear that are indistinguishable from today’s. But that is 140,000 years later than the estimated age of the new Adam, leading to the question: was he even “human”?</p>
<p>Answering this is tricky. There was no single moment when we became human, but rather a <a href="https://theconversation.com/what-makes-us-human-genetics-culture-or-both-14505">gradual process</a>. On an evolutionary timescale, Adam was very recent, and even if he was not “anatomically modern”, he could probably walk down a street today without raising too many eyebrows. </p>
<p>Given the scarcity of Perry’s branch and the lack of diversity within it, it is also possible that the revised Adam could have been an ancestor of two sub-species (or even species). Could one have become modern humans, while another produced a cousin? What if, long after modern humans had become established and started to spread, they should meet and interbreed? Like all our other close relatives, these cousins eventually disappeared, but maybe they left traces, such as Perry’s Y chromosome, in the modern gene pool. </p>
<p>This may sound shocking, but it would not be unprecedented. When modern humans spread from Africa to Eurasia, they met another cousin, the Neanderthals. Fossils with features from both species have long caused debate, and recently genetic evidence has suggested that today’s non-Africans owe 1 to 4% of their ancestry to <a href="http://accuca.conectia.es/noticias/2007/20070303_neanderthal_within.htm">such interbreeding</a>, although no Y chromosomes have yet been identified.</p>
<p>So, like many discoveries, Perry’s Y chromosome raises more questions than it answers. It will doubtless be fascinating to watch our understanding evolve as the genetics of more individuals, modern and ancient, from more locations are added to the picture.</p>
<hr>
<p><em>Correction: This post was modified to reflect that DNA test was performed on two of Perry’s descendants, rather than on Perry.</em></p><img src="https://counter.theconversation.com/content/15835/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Zadik does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The DNA of Albert Perry may change the story of human origins. Perry was an African-American born into slavery in South Carolina. An analysis of the DNA of his descendants produced results that came as…Daniel Zadik, Postdoctoral researcher in genetics, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/157252013-07-03T04:33:33Z2013-07-03T04:33:33ZMeet mama, papa and mama: how three-parent IVF works<figure><img src="https://images.theconversation.com/files/26761/original/ky37qp8f-1372823641.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mitochondrial genes are inherited from our mothers’ eggs and passed on through her daughters to subsequent generations.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The UK government has announced its <a href="http://www.bionews.org.uk/page_318118.asp">intention to draft proposals</a> allowing carriers of mitochondrial disease to have babies using a controversial IVF treatment that’s currently prohibited. The procedure is controversial because the babies will inherit DNA from three genetic parents.</p>
<p>The draft proposals will detail the regulation of the procedure and need to be endorsed by public consultation and parliament before being put into practice.</p>
<h2>The mighty mitochondria</h2>
<p>Mitochondrial DNA diseases offer distinct challenges to scientists and clinicians because we inherit our mitochondrial DNA in a different manner to our chromosomal genes. Our mitochondrial genes are passed down from our mothers’ eggs and on through her daughters to subsequent generations. </p>
<p>Mitochondrial genes are located in very small bodies called mitochondria and not with the chromosomes in the nucleus of the cell, which determine characteristics such as hair and eye colour.</p>
<p>The mitochondria are the “powerhouses” of the cell as they generate energy. Our cells use this form of energy for their everyday functions; mitochondrial genes are essential to this process. </p>
<p>If one of these genes is mutated, the individual may suffer from very debilitating diseases that affect, for example, muscle and nerve function. There are an increasing number of diseases that are associated with these mutations including diseases we hear about everyday, such as diabetes and Alzheimer’s disease. </p>
<p>The dilemma for a woman who carries mitochondrial DNA disease is that she doesn’t know how much damaged mitochondrial DNA is present in each of her eggs; each of these eggs is likely to have a different amount of mutation. Also, there’s no simple genetic test that can be used to tell the carrier whether her child would be affected. </p>
<p>So, if she and her partner choose to have a family, they will have no idea of the outcome – for them, it’s simply a matter of chance.</p>
<h2>Overcome mitochondrial disease</h2>
<p>Scientists are now developing two approaches to try and prevent children from inheriting these diseases. </p>
<p>The first of these techniques will transfer the mother’s chromosomes from one of her eggs into an egg from a donor. The donor egg would have had its chromosomes removed but retains its healthy mitochondrial DNA. </p>
<p>Then, as with normal IVF treatment, the eggs are fertilised with her partner’s sperm and the resultant embryo can develop for a few days in the lab before being transferred to the chromosomal mother to implant into her womb.</p>
<p>The second technique is similar but would first allow the partner’s sperm to fertilise the egg and then transfer the mother’s and father’s chromosomes to a healthy (empty apart from mitochondria) donor egg.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/26764/original/b5by5ywb-1372824517.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/26764/original/b5by5ywb-1372824517.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/26764/original/b5by5ywb-1372824517.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/26764/original/b5by5ywb-1372824517.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/26764/original/b5by5ywb-1372824517.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/26764/original/b5by5ywb-1372824517.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/26764/original/b5by5ywb-1372824517.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The controversy around these approaches lies with the baby having three genetic parents.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The controversy around these approaches lies with the baby having three genetic parents. These are the chromosomes that the mother and father contribute, as is normal following fertilisation. And then there’s the “third parent” – the mitochondrial DNA mother who donated the egg.</p>
<h2>Some things to consider</h2>
<p>Some groups argue that scientists are entering the brave new world of designer babies and that these techniques are similar to cloning. For them, these procedures are unacceptable.</p>
<p>Others argue that the technologies offer significant benefits, such as the potential to eradicate mitochondrial diseases. </p>
<p>In many respects, UK scientists are at the forefront of convincing government to legalise these procedures under the control of the country’s fertility regulator, the <a href="http://www.hfea.gov.uk/index.html">Human Fertilisation and Embryology Authority</a>.</p>
<p>In the last two years, there have been two significant reports supporting these procedures but they contained important reservations. In 2012, the UK’s <a href="http://www.nuffieldbioethics.org/mitochondrial-dna-disorders">Nuffield Council on Bioethics ruled</a>: </p>
<blockquote>
<p>If further research shows these techniques to be sufficiently safe and effective, we think it would be ethical for families to use them if they wished to, provided they receive an appropriate level of information and support. </p>
</blockquote>
<p>The Human Fertilisation and Embryology Authority sought public views on behalf of the secretary of state for health and <a href="http://www.hfea.gov.uk/7796.html">reported in late March, 2013</a>. It noted: </p>
<blockquote>
<p>… there is general support for permitting mitochondria replacement in the UK, so long as it is safe enough to offer in a treatment setting and is done so within a regulatory framework.</p>
</blockquote>
<p>These reservations are important because they are directed to two key aspects of the procedures. The first is whether any of the mutant mitochondrial DNA accompanies the chromosomes as they are transferred into the donor egg. </p>
<p>This is very important as even a small amount of mutant mitochondrial DNA in the egg can become the dominant population in the baby and lead to mitochondrial disease. We are unsure why this happens but this is currently an area of intense research activity.</p>
<p>The second is whether these techniques would lead to the baby suffering from any harmful side effects.</p>
<p>While I fully embrace these new approaches to fight mitochondrial disease, we still need to make significant advances in determining their safety and effectiveness, and they require a considerable amount of validation. </p>
<p>If they pass these tests, these technologies offer ways to prevent mitochondrial genetic disease from being passed from a female to her descendants through one round of assisted reproduction.</p><img src="https://counter.theconversation.com/content/15725/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Justin St. John receives funding from NHMRC, which looks at mitochondrial mutations and previously held a grant from the UK MRC, which looked at cloned embryos and mitochondrial inheritance. </span></em></p>The UK government has announced its intention to draft proposals allowing carriers of mitochondrial disease to have babies using a controversial IVF treatment that’s currently prohibited. The procedure…Justin St. John, Professor and Director, Centre for Genetic Diseases, Monash Institute of Medical Research, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/119992013-02-05T02:58:33Z2013-02-05T02:58:33ZMore than a hunch: identifying Richard III with DNA<figure><img src="https://images.theconversation.com/files/19949/original/b293kq29-1360028336.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The skeleton of Richard III was discovered beneath a car park in Leicester, and identified using the DNA of his descendants.</span> <span class="attribution"><span class="source">EPA/HO</span></span></figcaption></figure><p>In the past few days news has come to light of the <a href="http://www.guardian.co.uk/science/2013/feb/04/richard-iii-dna-bones-king">confirmation</a> that skeletal remains discovered in an excavated site of a Leicester car park are indeed that of the famous English king Richard III. But how was it done?</p>
<p>It should be noted that DNA played only a part in this puzzle, the project involved archaeologists, pathologists, genealogists and anthropologists. </p>
<p>It has been <a href="http://edition.cnn.com/2013/02/03/world/europe/richard-iii-search-announcement/index.html">reported</a> that testing produced a match with the maternal DNA of two descendants of Richard’s sister (one anonymous, and the other Michael Ibsen, a Canadian carpenter living in London). A “beyond reasonable doubt” match by all accounts. </p>
<p>So what does this actually mean and how can DNA be considered such a useful tool to identify the dead?</p>
<p>Most people who are interested in the field of forensic science would be familiar with DNA profiling. In shows such as <a href="http://www.imdb.com/title/tt0247082/">CSI: Crime Scene Investigation</a> it is used quickly and cleanly to great crime-fighting effect. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/wR1IjOVWI7Y?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The reality of course is somewhat different, but in essence what you see on screen is as it occurs in the lab. The DNA used mostly in the criminal forensic realm is that termed <a href="http://www.latimes.com/news/science/sciencenow/la-sci-sn-richard-iii-mitochondrial-dna-20130104,0,5536883.story">“nuclear DNA”</a>. This large DNA strand is found in the middle of most cells of the body, its role being to act as a blueprint for building and operating your body. </p>
<p>Its sequence is very unique. Your nuclear DNA is inherited in part from your father, and in part from your mother. The “letters” in their DNA codes combine to produce an approximately 3.2 billion base pair-long strand believed to be unlike anyone else’s (aside from an identical twin). It can be used to individualise biological evidence from crime scenes - effectively pinpointing an individual as the source. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/19953/original/nwjj5xxd-1360028805.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The complete skeleton of Richard III as discovered in a Leicester car park.</span>
<span class="attribution"><span class="source">EPA/HO/University of Leicester</span></span>
</figcaption>
</figure>
<p>When identifying bloodstains from a murder, or semen from a rape, this technique can be invaluable. Being a large molecule, however, nuclear DNA is susceptible to damage, which can be fatal to the scientist’s ability to read it’s code. </p>
<p>This means that when evidence items or biological material has been left exposed to the elements – such as moisture, sunlight, or chemical environments - its value for unique identification can be reduced. Enter <a href="http://ghr.nlm.nih.gov/chromosome/MT">mitochondrial DNA</a>.</p>
<h2>Mitochondrial DNA</h2>
<p>Mitochondria are the power-houses of the cells. They are present in virtually all cells both plant and animal. They convert energy into forms that can be used to drive cellular reactions and processes.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=755&fit=crop&dpr=1 600w, https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=755&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=755&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=949&fit=crop&dpr=1 754w, https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=949&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/19955/original/jmkfrkt8-1360029293.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=949&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A portrait of the slain English king Richard III.</span>
<span class="attribution"><span class="source">EPA/ The Dean and Chapter of Leicester </span></span>
</figcaption>
</figure>
<p>This is the much neglected “other” DNA contained within our bodies, and it has been used effectively to identify skeletal remains from hundreds, even thousands of years past. </p>
<p>To make the regal link: recently mitochondrial work has been <a href="http://news.nationalgeographic.com.au/news/2008/06/080606-egypt-mummies.html">undertaken on Egyptian royal mummies</a> from the Valley of the Kings. No less than Tutankhamen has had his familial relationships probed and documented via his mitochondrial DNA. </p>
<p>Moving further north, the Russian royal family (the Romanovs) were <a href="http://articles.latimes.com/2009/mar/11/science/sci-romanov11">also identified</a> after a grisly dispatch using the same process.</p>
<p>So why go down the mitochondrial path when nuclear DNA fails us? </p>
<p>In line with their functional importance, mitochondria are rewarded by both quantity and size in their cellular home. Your average cell contains hundreds or even thousands of circular mitochondrial DNA strands. This gives them an advantage over the more fragile, singular nuclear DNA. They are smaller, more robust and by weight of numbers - they are more likely to survive the slings and arrows of time and outrageous fortune. </p>
<p>The other advantage of mitochondrial DNA is that it is inherited solely on the maternal line. When egg and sperm combine at the moment of conception, the sperm tail containing the parental mitochondria is shed. The resulting embryo will now inherit the mitochondrial sequence from the mother. As there is no combining of codes the original sequence is (generally) maintained. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/19940/original/2gfjc673-1360025661.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The final resting place of Richard III was discovered over 500 years after his death.</span>
<span class="attribution"><span class="source">HO/EPA/University of Leicester</span></span>
</figcaption>
</figure>
<p>Less change and mutation means that even many generations down the line the sequence can be compared and matched. It also means when only distant relatives (such as maternal aunts or cousins etc) can be found for matching, a result is still possible. This kind of matching with standard nuclear DNA profiling is far less discerning.</p>
<p>So, where does this leave us with a king and a carpenter? King Richard and his sister would have inherited the same maternal mitochondrial DNA. This has in turn been carried down the line in Michael Ibsen’s family (thank goodness there appear to be no other skeletons in his family’s closet!). </p>
<p>A direct comparison would have been carried out, and (perhaps allowing for minimal mutation) a match would have been detected. A statistical analysis of the frequency of the profile within a population would have been undertaken and the result was such that scientists consider his identity “beyond reasonable doubt”.</p>
<p>It has been quipped that there is some irony in the fact that the man Shakespeare made famous for his “my kingdom for a horse” speech should be found in a car park. That aside, it is yet another testament to the value of the technique of DNA identification that makes a DNA scientist feel all warm and fuzzy. </p>
<p><strong>Further reading:</strong> <br> <a href="https://theconversation.com/a-burial-fit-for-a-king-from-car-park-to-cathedral-for-richard-iii-12001">A burial fit for a king: from car park to cathedral for Richard III</a> - Peter Sherlock, The Conversation</p><img src="https://counter.theconversation.com/content/11999/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jane Devenish-Meares does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In the past few days news has come to light of the confirmation that skeletal remains discovered in an excavated site of a Leicester car park are indeed that of the famous English king Richard III. But…Jane Devenish-Meares, Scientist, Molecular Biology, Victorian Institute of Forensic MedicineLicensed as Creative Commons – attribution, no derivatives.