tag:theconversation.com,2011:/us/topics/fluorescence-37333/articlesFluorescence – The Conversation2023-10-04T21:19:46Ztag:theconversation.com,2011:article/2150152023-10-04T21:19:46Z2023-10-04T21:19:46ZQuantum dots are part of a revolution in engineering atoms in useful ways – Nobel Prize for chemistry recognizes the power of nanotechnology<figure><img src="https://images.theconversation.com/files/552184/original/file-20231004-19-i1snbm.jpg?ixlib=rb-1.1.0&rect=143%2C24%2C3655%2C2727&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Flasks of quantum dots fluorescing at the Nobel Prize announcement.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/laboratory-flasks-are-used-for-explanation-during-the-news-photo/1705001725">Jonathan Nackstrand/AFP via Getty Images</a></span></figcaption></figure><p>The 2023 Nobel Prize for chemistry <a href="https://www.nobelprize.org/prizes/chemistry/2007/summary/">isn’t the</a> <a href="https://www.nobelprize.org/prizes/physics/1986/summary/">first Nobel</a> <a href="https://www.nobelprize.org/prizes/chemistry/2010/summary/">awarded for</a> <a href="https://www.nobelprize.org/prizes/chemistry/2016/summary/">research in</a> <a href="https://www.nobelprize.org/prizes/chemistry/1996/summary/">nanotechnology</a>. But it is perhaps the most colorful application of the technology to be associated with the accolade.</p>
<p>This year’s prize recognizes <a href="https://scholar.google.com/citations?user=8086TkwAAAAJ&hl=en&oi=ao">Moungi Bawendi</a>, <a href="https://scholar.google.com/citations?user=GT0oh5QAAAAJ&hl=en&oi=ao">Louis Brus</a> and <a href="https://www.nobelprize.org/prizes/chemistry/2023/ekimov/facts">Alexei Ekimov</a> for the <a href="https://www.nobelprize.org/prizes/chemistry/2023/press-release/">discovery and development of quantum dots</a>. For many years, these <a href="https://doi.org/10.1021/acsanm.0c01386">precisely constructed nanometer-sized particles</a> – just a few hundred thousandths the width of a human hair in diameter – were the darlings of nanotechnology pitches and presentations. As a <a href="https://scholar.google.com/citations?user=b8NhWc4AAAAJ&hl=en">researcher</a> and <a href="https://en.wikipedia.org/wiki/Andrew_D._Maynard">adviser</a> on nanotechnology, <a href="https://2020science.org/wp-content/uploads/2009/01/maynard-ucla-090417-handouts.pdf">I’ve even used them myself</a> when talking with developers, policymakers, advocacy groups and others about the promise and perils of the technology.</p>
<p>The origins of nanotechnology predate Bawendi, Brus and Ekimov’s work on quantum dots – the physicist Richard Feynman speculated on what could be possible through nanoscale engineering <a href="http://calteches.library.caltech.edu/1976/">as early as 1959</a>, and engineers like Erik Drexler were speculating about the possibilities of atomically precise manufacturing <a href="https://www.penguinrandomhouse.com/books/42881/engines-of-creation-by-k-eric-drexler/">in the the 1980s</a>. However, this year’s trio of Nobel laureates were part of the earliest wave of modern nanotechnology where researchers began <a href="https://andrewmaynard.substack.com/p/living-in-a-material-world">putting breakthroughs in material science to practical use</a>.</p>
<p>Quantum dots brilliantly <a href="https://www.britannica.com/science/fluorescence">fluoresce</a>: They absorb one color of light and reemit it nearly instantaneously as another color. A vial of quantum dots, when illuminated with broad spectrum light, shines with a single vivid color. What makes them special, though, is that their color is determined by how large or small they are. Make them small and you get an intense blue. Make them larger, though still nanoscale, and the color shifts to red.</p>
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<span class="caption">The wavelength of light a quantum dot emits depends on its size.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.3389/fnins.2015.00480">Maysinger, Ji, Hutter, Cooper</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>This property has led to many arresting images of rows of vials containing quantum dots of different sizes going from a striking blue on one end, through greens and oranges, to a vibrant red at the other. So eye-catching is this demonstration of the power of nanotechnology that, in the early 2000s, quantum dots became iconic of the strangeness and novelty of nanotechnology.</p>
<p>But, of course, quantum dots are more than a visually attractive parlor trick. They demonstrate that unique, controllable and useful interactions between matter and light can be achieved through engineering the physical form of matter – modifying the size, shape and structure of objects, for instance – rather than playing with the chemical bonds between atoms and molecules. The distinction is an important one, and it’s at the heart of modern nanotechnology.</p>
<h2>Skip chemical bonds, rely on quantum physics</h2>
<p>The wavelengths of light that a material absorbs, reflects or emits are usually determined by the chemical bonds that bind its constituent atoms together. <a href="https://www.sciencedirect.com/topics/engineering/synthetic-dye">Play with the chemistry of a material</a> and it’s possible to fine-tune these bonds so that they give you the colors you want. For instance, some of the earliest dyes <a href="https://thedreamstress.com/2013/09/terminology-what-are-aniline-dyes-or-the-history-of-mauve-and-mauveine/">started with a clear substance such as aniline</a>, transformed through chemical reactions to the desired hue.</p>
<p>It’s an effective way to work with light and color, but it also leads to products that <a href="https://www.sciencemuseum.org.uk/objects-and-stories/chemistry/colourful-chemistry-artificial-dyes">fade over time as those bonds degrade</a>. It also frequently involves using chemicals that are <a href="https://doi.org/10.1016/B978-0-12-822850-0.00013-2">harmful to humans and the environment</a>.</p>
<p>Quantum dots work differently. Rather than depending on chemical bonds to determine the wavelengths of light they absorb and emit, they rely on very small clusters of semiconducting materials. It’s the <a href="https://www.britishcouncil.org/voices-magazine/what-quantum-dot">quantum physics of these clusters</a> that then determines what wavelengths of light are emitted – and this in turn depends on how large or small the clusters are.</p>
<p>This ability to tune how a material behaves by simply changing its size is a game changer when it comes to the intensity and quality of light that quantum dots can produce, as well as their resistance to bleaching or fading, their novel uses and – if engineered smartly – their toxicity.</p>
<p>Of course, few materials are completely nontoxic, and quantum dots are no exception. Early quantum dots were often based on cadmium selenide for instance – the component materials of which are toxic. However, the <a href="https://theconversation.com/are-quantum-dot-tvs-and-their-toxic-ingredients-actually-better-for-the-environment-35953">potential toxicity of quantum dots needs to be balanced</a> by the likelihood of release and exposure and how they compare with alternatives. </p>
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<a href="https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="people walk past colorful multi-screen display at a trade show" src="https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&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">Quantum dots are now a normal part of many consumer items, including televisions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/trade-visitors-walk-past-televisions-with-quantum-dots-news-photo/1040134228">Soeren Stache/picture alliance via Getty Images</a></span>
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<p>Since its earlier days, quantum dot technology has evolved in safety and usefulness and has found its way into an increasing number of products, from <a href="https://www.wired.com/2015/01/primer-quantum-dot/">displays</a> and <a href="https://doi.org/10.1021/acs.chemrev.2c00695">lighting</a>, to <a href="https://doi.org/10.1016/B978-0-323-88431-0.00025-9">sensors</a>, <a href="https://doi.org/10.2147/IJN.S357980">biomedical applications</a> and more. In the process, some of their novelty has perhaps worn off. It can be hard to remember just how much of a quantum leap the technology is that’s being used to promote the <a href="https://www.cnet.com/tech/home-entertainment/this-top-secret-prototype-display-will-blow-your-mind/">latest generation of flashy TVs</a>, for instance.</p>
<p>And yet, quantum dots are a pivotal part of a technology transition that’s revolutionizing how people work with atoms and molecules.</p>
<h2>‘Base coding’ on an atomic level</h2>
<p>In my book “<a href="https://andrewmaynard.net/films-from-the-future/">Films from the Future: the Technology and Morality of Sci-Fi Movies</a>,” I write about the concept of “<a href="https://andrewmaynard.substack.com/p/how-our-mastery-of-biological-physical-and-cyber-base-code-is-transforming-how-we-think-about-b2eae9d589d0">base coding</a>.” The idea is simple: If people can manipulate the most basic code that defines the world we live in, we can begin to redesign and reengineer it. </p>
<p>This concept is intuitive when it comes to computing, where programmers use the “base code” of 1’s and 0’s, albeit through higher level languages. It also makes sense in biology, where scientists are becoming increasingly adept at reading and writing the base code of DNA and RNA – in this case, using the chemical bases adenine, guanine, cytosine and thymine as their coding language. </p>
<p>This ability to work with base codes also extends to the material world. Here, the code is made up of atoms and molecules and how they are arranged in ways that lead to novel properties.</p>
<p>Bawendi, Brus and Ekimov’s work on quantum dots is a perfect example of this form of material-world base coding. By precisely forming small clusters of particular atoms into spherical “dots,” they were able to tap into novel quantum properties that would otherwise be inaccessible. Through their work they demonstrated the transformative power that comes through coding with atoms.</p>
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<a href="https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="alt" src="https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=514&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=514&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=514&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=646&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=646&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=646&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An example of ‘base coding’ using atoms to create a material with novel properties is a single molecule ‘nanocar’ crafted by chemists that can be controlled as it ‘drives’ over a surface.</span>
<span class="attribution"><a class="source" href="https://news.rice.edu/news/2020/rice-rolls-out-next-gen-nanocars">Alexis van Venrooy/Rice University</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>They paved the way for increasingly sophisticated nanoscale base coding that is now leading to products and applications that would not be possible without it. And they were part of the inspiration for a <a href="https://www.nature.com/articles/d41586-022-02146-4">nanotechnology revolution</a> that is continuing to this day. Reengineering the material world in these novel ways far transcends what can be achieved through more conventional technologies.</p>
<p>This possibility was captured in a 1999 U.S. National Science and Technology Council report with the title <a href="https://trid.trb.org/view/636880">Nanotechnology: Shaping the World Atom by Atom</a>. While it doesn’t explicitly mention quantum dots – an omission that I’m sure the authors are now kicking themselves over – it did capture just how transformative the ability to engineer materials at the atomic scale could be.</p>
<p>This atomic-level shaping of the world is exactly what Bawendi, Brus and Ekimov aspired to through their groundbreaking work. They were some of the first materials “base coders” as they used atomically precise engineering to harness the quantum physics of small particles – and the Nobel committee’s recognition of the significance of this is well deserved.</p><img src="https://counter.theconversation.com/content/215015/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Maynard has previously received funding for nanotechnology-based work from the National Institutes of Health, the National Science Foundation, and the Pew Charitable Trusts</span></em></p>Quantum dots are a prime example of the way nanotechnology engineers materials at an atomic scale.Andrew Maynard, Professor of Advanced Technology Transitions, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2145842023-10-03T23:06:07Z2023-10-03T23:06:07ZFrom glowing cats to wombats, fluorescent mammals are much more common than you’d think<p>Recently, several mammals have been reported to “glow” under ultraviolet (UV) light, including our beloved platypus. But no one knew how common it was among mammals until now.</p>
<p>Our research, published <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.230325">in Royal Society Open Science today</a>, found this glow – known as fluorescence – is extremely common. Almost every mammal we studied showed some form of fluorescence.</p>
<p>We also examined the glow to determine if it was really fluorescence and not some other phenomenon. Then, we tested if the fluorescence we observed in museum specimens was natural and not caused by preservation methods.</p>
<p>We also searched for links between the type and degree of fluorescence and the lifestyle of each species, to gain insights on whether there are any benefits to glowing under UV if you’re a mammal.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1323496257986260992"}"></div></p>
<h2>Nightclub lights</h2>
<p>Nightclub visitors will be familiar with white clothes, or perhaps their gin and tonic, glowing blue under UV light. This is a great example of fluorescence – when the energy from UV light, which is a form of electromagnetic radiation invisible to humans, is absorbed by certain chemicals. </p>
<p>These chemicals then emit visible light, which is lower-energy electromagnetic radiation. In the case of gin and tonic, this is due to the presence of the quinine molecule in the tonic water. </p>
<p>In the case of animals, this can be due to proteins or pigments in their scales, skin or fur. Fluorescence is quite common among animals. It <a href="https://royalsocietypublishing.org/doi/full/10.1098/rstb.2016.0335?rss=1">has been reported</a> for birds, reptiles, amphibians, fish, corals, molluscs and most famously scorpions and other arthropods.</p>
<p>However, it has been described less frequently in mammals, although recent studies have provided several examples. We already knew that bones and teeth glow with fluorescence, as do white human hair and nails. Some rodents have a pink glow under UV light and platypuses <a href="https://www.degruyter.com/document/doi/10.1515/mammalia-2020-0027/html">glow blue-green</a>. </p>
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Read more:
<a href="https://theconversation.com/explainer-what-is-the-electromagnetic-spectrum-8046">Explainer: what is the electromagnetic spectrum?</a>
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<a href="https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A glowing blue drink on a table in a dark restaurant" src="https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.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>
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<span class="caption">The reason a gin and tonic looks fluorescent under UV lighting is thanks to the quinine in the tonic.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Glowing_cocktail.jpg">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>How often do mammals glow?</h2>
<p>Our team came together because we were curious about fluorescence in mammals. We wanted to know if the glow reported recently for various species was really fluorescence, and how widespread this phenomenon was. We obtained preserved and frozen specimens from museums and wildlife parks to study.</p>
<p>We started with the platypus to see if we could replicate the previously reported fluorescence. We photographed preserved and frozen platypus specimens under UV light and observed a fluorescent (although rather faint) glow.</p>
<p>To make sure it was fluorescence and not some other effect that looked like it, we used a technique called fluorescence spectroscopy. </p>
<p>This involved shining various sources of light at the samples and recording the specific “fingerprints” of the resulting glow, known as an <a href="https://www.britannica.com/science/spectrum#ref11393">emission spectrum</a>. This way, we could confirm what we saw was indeed fluorescence.</p>
<p>We repeated this process for other mammals and found clear evidence of fluorescence in the white fur, spines and even skin and nails of koalas, Tasmanian devils, short-beaked echidnas, southern hairy-nosed wombats, quendas (bandicoots), greater bilbies and even cats.</p>
<p>Both fresh-frozen and chemically treated museum specimens were fluorescent. This meant it wasn’t preservation chemicals such as borax or arsenic causing the fluorescence. So, we concluded this was a real biological phenomenon. </p>
<h2>Mammals in dazzling lights</h2>
<p>Using specimens from the Western Australian Museum’s collection, we took the experiment to the next stage. We recorded every species of mammal that was fluorescent when we exposed the specimens to UV light.</p>
<p>As a result, we found 125 fluorescent species of mammal, representing all known orders. Fluorescence is clearly common and widely distributed among mammals.</p>
<p>In particular, we noticed that white and light-coloured fur is fluorescent, with dark pigmentation preventing fluorescence. For example, a zebra’s white stripes fluoresced while the dark stripes didn’t.</p>
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<em>
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Read more:
<a href="https://theconversation.com/zebras-stripes-are-a-no-fly-zone-for-flies-111888">Zebra's stripes are a no fly zone for flies</a>
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<p>We then used our dataset to test if fluorescence might be more common in nocturnal species. To do this, we correlated the total area of fluorescence with ecological traits such as nocturnality, diet and locomotion.</p>
<p>Nocturnal mammals were indeed more fluorescent, while aquatic species were less fluorescent than those that burrowed, lived in trees, or on land. </p>
<p>Based on our results, we think fluorescence is very common in mammals. In fact, it is likely the default status of hair unless it is heavily pigmented. This doesn’t mean fluorescence has a biological function – it may just be an artefact of the structural properties of unpigmented hair.</p>
<p>However, we suggest florescence may be important for brightening pale-coloured parts of animals that are used as visual signals. This could improve their visibility, especially in poor light – just like the fluorescent optical brighteners that are added to white paper and clothing.</p><img src="https://counter.theconversation.com/content/214584/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kenny Travouillon received funding from the Australian Biological Resources Study and is an adjunct at Curtin University. </span></em></p><p class="fine-print"><em><span>Christine Elizabeth Cooper receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Jemmy Bouzin receives funding from the Government of Seychelles. </span></em></p><p class="fine-print"><em><span>Linette Umbrello receives funding from the Australian Biological Resources Study and is a Research Associate at the Western Australian Museum. </span></em></p><p class="fine-print"><em><span>Simon Lewis 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>After combing through museum collections, our team of researchers found a whopping 125 fluorescent mammal species – from polar bears and dolphins, to leopards, zebras and wombats.Kenny Travouillon, Curator of Mammals, Western Australian MuseumChristine Elizabeth Cooper, Senior Lecturer, Curtin UniversityJemmy Bouzin, PhD candidate, Curtin UniversityLinette Umbrello, Postdoctoral research associate, Queensland University of TechnologySimon Lewis, Professor of Forensic and Analytical Chemistry, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1846592022-07-28T14:35:42Z2022-07-28T14:35:42ZShining fluorescent light on bee sperm could help explain colony survival<figure><img src="https://images.theconversation.com/files/467758/original/file-20220608-20-fs4cf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Ivan Marjanovic/Shutterstock</span></span></figcaption></figure><p>Form follows function. This is the principle that the design or shape of something – whether made by humans or in nature – should serve a purpose.</p>
<p>Honey bees’ function is to pollinate plants, make honey, survive and reproduce. Along with other pollinators – birds, moths, butterflies, bats and many more – they are the unsung forces behind much of what people eat, drink and even wear. Animal pollinators are said to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8396518/">contribute</a> to the production of 87 global crops in 200 countries, including 30% of the world’s food crops. Their labours have been valued at around 153 billion euros.</p>
<p>But in one <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320718313636">review paper</a>, researchers suggest that at current rates of decline, the world will lose some 40% of its insect species, including bees, over the next few decades. Among the causes are widespread use of <a href="https://www.reuters.com/article/us-science-europe-pesticides/pesticides-put-bees-at-risk-european-watchdog-confirms-idINKCN1GC18G">pesticides</a> and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320718313636">habitat loss</a>.</p>
<p>Bee colonies are collapsing around the world. In Europe, a <a href="https://ec.europa.eu/food/system/files/2017-04/la_bees_epilobee-report_2012-2014.pdf">2012-2014 survey</a>, the first of its kind, by the European Commission estimated that some countries were losing as many as a third of their colonies every year.</p>
<p>The threats to their survival make it urgent to understand the relationship between form and function in honey bees, particularly the sperm of the male bees (drones) – the “<a href="https://www.smithsonianmag.com/science-nature/key-honey-bee-conservation-bee-semen-180969676/">flying genitalia</a>” of the bee world, as one researcher described them. That’s because of the way bees mate and reproduce.</p>
<p>Researchers around the world are applying the latest technologies to this project. One technique is computer-aided sperm analysis. This assesses sperm function (its vitality and movement) and its structural parameters. At the comparative spermatology group at the University of the Western Cape in South Africa, we have a particular interest in the structure and movement of insect sperm. We’ve now <a href="https://doi.org/10.1080/00218839.2022.2090729">pioneered</a> the use of fluorescent microscopy in combination with computer-aided sperm analysis for what we believe are superior results.</p>
<p>In addition to motility and velocity, our in-depth analyses provide data on, among other things, the swimming patterns of honey bee sperm. This fluorescent method shows promise and can, <a href="https://doi.org/10.1080/00218839.2022.2090729">we argue</a>, provide baseline data for future studies evaluating honey bee sperm quality. </p>
<p>This matters as we seek to secure the survival of honey bee colonies.</p>
<h2>Choosy queen bees</h2>
<p>For now, South Africa and African honey bees appear to have been spared the colony losses seen in some parts of the world. This is thanks to the continuing use of traditional beekeeping practices, according to a <a href="https://www.fao.org/3/i2462e/i2462e.pdf">2012 report</a> by the United Nations’ Food and Agricultural Organisation.</p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/lessons-from-africa-on-how-to-build-resilient-bee-colonies-131478">Lessons from Africa on how to build resilient bee colonies</a>
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<p>But the threat, as evidenced by the situation in Europe, can’t be ignored. </p>
<p>There is some urgency to understanding the sperm quality of the honey bee drones because of how long it has to last. Bee queens have limited mating flights. They fly to what’s known as a drone congregation area and mate with multiple drones before heading back to the colony. The queen <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2718501/#:%7E:text=Honeybee%20queens%20are%20efficient%20sperm,on%20the%20honeybee%20mating%20system">can store</a> some six million sperm in a specialised sac, the spermatheca, for as long as seven years. Any one queen bee can potentially have around 1.7 million offspring.</p>
<p>So, she needs the best and most resilient sperm she can get. And she will be choosy, shedding some sperm and keeping only what she likes. It’s not known how the queen decides which sperm is chosen or shed. </p>
<p>This is where form and function meet. Honey bee sperm has a very long tail, about 225 micrometres (µm) in length. It dwarfs the tails of the sperm of larger vertebrates, which are typically in the 40-75 µm range.</p>
<p>Why these long tails? Do they aid motility – how strongly and how fast the sperm moves? Are they relevant to the sperm’s longevity in the queen’s sperm sac? Do they determine which sperm the queen decides to hold on to and which to shed?</p>
<p>To answer these questions, we need the right technology. </p>
<h2>Technology sheds light</h2>
<p>Honey bee sperm are devilishly difficult to study, even with powerful microscopes and tried-and-tested techniques such as <a href="https://www.microscopyu.com/techniques/phase-contrast/introduction-to-phase-contrast-microscopy">phase-contrast microscopy</a>, a technique that allows more contrast in a viewed sample. This has much to do with the sperm’s form and structure. The tails are often tightly coiled in a helix, making it hard to tell which is the tail and which the head of the sperm. Both have about the same width. </p>
<p>Other studies of sperm motility and kinematic parameters – broadly, the direction and range of movement – have tried to work around these blind spots, but at the expense of thorough analysis.</p>
<p>Our research group has adapted and stacked existing technology to study the sperm of the <a href="https://pubmed.ncbi.nlm.nih.gov/31383288/">black soldier fly</a> and <a href="https://www.micropticsl.com/bee-sperm-2/">the Cape honey bee</a>. </p>
<p>In our <a href="https://doi.org/10.1080/00218839.2022.2090729">first published paper</a> about this work, we explain how we have improved on other sperm analysis systems by using fluorescence. This has also been done successfully in studies of human sperm. Only sperm heads fluoresce – glow brightly – so it is much simpler to distinguish head from tail.</p>
<p>This has allowed us to glean useful insights into sperm concentration among drones. We’ve also been able to confirm the three swimming patterns of sperm: moving in single helices (wound-up), progressively forward snake-like swimmers, and what we describe as groups of helical swimming sperm (as compared to the individual helical swimmers).</p>
<h2>Protecting colonies</h2>
<p>Sperm quality has also been put forward as a cause of colony collapse. This sort of research broadens our understanding of sperm quality’s importance for colony health and performance. Researchers elsewhere have <a href="https://doi.org/10.1093/jisesa/ieab048">suggested</a> that drone quality (which we believe includes sperm quality) and variability in a colony or apiary can be a useful indicator of queen and colony health. It can therefore also be used to identify the effect of, for example, environmental stressors. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-honeybees-in-south-africa-need-from-people-better-managed-forage-166369">What honeybees in South Africa need from people: better managed forage</a>
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<p>Assessing sperm quality as part of drone quality will allow for early detection of such stressors. That will allow for preventive management strategies to avoid colony deterioration.</p>
<p>We still have much to learn about honey bee sperm and colony collapses. But if it means we can aid beekeepers to track colony health, for instance, perhaps we can help to secure the future of this critical pollinator. </p>
<p><em>The research on which this article is based was co-authored by Master’s student Janice Murray. Mike Allsopp of the Agricultural Research Council helped to collect data in the field.</em></p><img src="https://counter.theconversation.com/content/184659/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christina Kotze receives funding from National Research Foundation (NRF); Thuthuka funding instrument; Grant number: TTK180407318351.
</span></em></p><p class="fine-print"><em><span>Gerhard van der Horst is an Emeritus Professor of Medical Bioscience at UWC and an Extra-Ordinary Professor at the University of Stellenbosch. He is also a senior consultant to Microptic SL, Barcelona, Spain in the field of Computer Aided Sperm Analysis</span></em></p>Studying bee sperm is difficult because of the way it coils, but fluorescent light illuminates the head of the sperm. Sperm quality may indicate stress levels in the bee colony.Christina Kotze, Lecturer in anatomy and physiology, and researcher in invertebrate reproductive biology, University of the Western CapeGerhard van der Horst, Emeritus Professor UWC, Extra-Ordinary Professor SU, expert comparative spermatologist, University of the Western CapeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1578562021-05-10T12:31:27Z2021-05-10T12:31:27ZDNA ‘Lite-Brite’ is a promising way to archive data for decades or longer<figure><img src="https://images.theconversation.com/files/399089/original/file-20210505-13-w8uydd.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3072%2C2041&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A simple two-dimensional grid can convey a lot of information – whether making pictures with Lite-Brite or storing data in DNA.</span> <span class="attribution"><a class="source" href="https://flickr.com/photos/52076395@N00/3801567473/">Justin Day/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>We and our colleagues have developed a way to store data using pegs and pegboards made out of DNA and retrieving the data with a microscope – a molecular version of the <a href="https://shop.hasbro.com/en-us/product/lite-brite-ultimate-classic:A0579FDA-BDE1-4888-840A-1862576A318E">Lite-Brite</a> toy. Our prototype stores information in patterns using DNA strands spaced about 10 nanometers apart. Ten nanometers is more than a thousand times smaller than the diameter of a human hair and about 100 times smaller than the diameter of a bacterium. </p>
<p>We tested our <a href="https://doi.org/10.1038/s41467-021-22277-y">digital nucleic acid memory</a> (dNAM) by storing the statement “Data is in our DNA!\n.” We described the research in a paper published in the journal Nature Communications on April 22, 2021.</p>
<p>Previous methods for retrieving data in DNA require the DNA to be sequenced. Sequencing is the process of <a href="https://www.genome.gov/about-genomics/fact-sheets/DNA-Sequencing-Fact-Sheet">reading the genetic code of strands of DNA</a>. Though it is a powerful tool in medicine and biology, it wasn’t designed with DNA memory in mind.</p>
<p>Our approach uses a microscope to read the data optically. Because the DNA pegs are positioned closer than half the wavelength of visible light, we used <a href="https://www.sciencemag.org/features/2016/05/superresolution-microscopy">super-resolution microscopy</a>, which circumvents the <a href="https://courses.lumenlearning.com/physics/chapter/27-6-limits-of-resolution-the-rayleigh-criterion/">diffraction limit</a> of light. This provides a way to read the encoded data without sequencing the DNA.</p>
<figure class="align-center ">
<img alt="Three columns and three rows of dots against a dark background" src="https://images.theconversation.com/files/399090/original/file-20210505-15-1moc0w7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399090/original/file-20210505-15-1moc0w7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=488&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399090/original/file-20210505-15-1moc0w7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=488&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399090/original/file-20210505-15-1moc0w7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=488&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399090/original/file-20210505-15-1moc0w7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=613&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399090/original/file-20210505-15-1moc0w7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=613&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399090/original/file-20210505-15-1moc0w7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=613&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Digital nucleic acid memory (dNAM) uses light-emitting DNA strands to read the data optically rather than requiring sequencing. The left column shows patterns designed for encoding data, the middle column shows optical readout of data stored in DNA using super-resolution microscopy, and the right column shows Atomic Force Microscope images of the DNA nanostructures. Each 6 x 8 pegboard is roughly 70 x 90 nanometers.</span>
<span class="attribution"><span class="source">Nucleic Acid Memory Institute at Boise State University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The patterns of DNA strands – the pegs – light up when fluorescently labeled DNA bind to them. Because the fluorescent strands are short, they rapidly bind and unbind. This causes them to blink, making it easier to separate one peg from another and read the stored information. We use the fluorescent patterns of each pegboard as a code to store chunks of data.</p>
<p>The microscope can image hundreds of thousands of the DNA pegs in a single recording, and our error-correction algorithms ensure we recover all of the data. After accounting for the bits used by the algorithms, our prototype was able to read data at a density of 330 gigabits per square centimeter.</p>
<h2>Why it matters</h2>
<p>You’re not likely to have a DNA storage device in your phone or computer, at least anytime soon. DNA data storage is promising for archival storage – storing large amounts of information for long periods of time. DNA can store a lot of information in a small space. It would be possible to <a href="https://doi.org/10.1038/nmat4594">store every tweet, email, photo, song, movie and book ever created</a> in a volume equivalent to a jewelry box. And data stored in DNA could last for centuries, given that the biomolecule has a <a href="https://www.nature.com/news/dna-has-a-521-year-half-life-1.11555">half-life of over 500 years</a>.</p>
<h2>What other research is being done</h2>
<p>Researchers have been <a href="https://www.scientificamerican.com/article/dna-data-storage-is-closer-than-you-think/">developing methods of storing data in DNA</a> for several decades. Those methods involve the design and synthesis of unique strings of information made from the DNA nucleotides adenine (A), thymine (T), cytosine (C) and guanine (G). This information is recovered by reading the strings using sequencing technology.</p>
<h2>What’s next</h2>
<p>From here, our goal is to increase the amount of data that we can store in dNAM, decrease the amount of time it takes to write and read the data, and use the technique to encrypt data.</p>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/157856/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Will Hughes receives funding from the National Science Foundation, the Semiconductor Research Corporation, and the State of Idaho.</span></em></p><p class="fine-print"><em><span>George Dickinson receives funding from the National Science Foundation, the Semiconductor Research Corporation, and the State of Idaho</span></em></p><p class="fine-print"><em><span>Luca Piantanida receives funding from the National Science Foundation, the Semiconductor Research Corporation, and the State of Idaho. </span></em></p>DNA has been storing vast amounts of biological information for billions of years. Researchers are working to harness DNA for archiving data. A new method uses light to simplify the process.Will Hughes, Professor of Materials Science & Engineering, Boise State UniversityGeorge David Dickinson, Post-Doctoral Research Scientist in Materials Science and Engineering, Boise State UniversityLuca Piantanida, Post-Doctoral Research Scientist in Materials Science and Engineering, Boise State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1443632020-08-26T12:24:13Z2020-08-26T12:24:13ZFive techniques we’re using to uncover the secrets of viruses<figure><img src="https://images.theconversation.com/files/353169/original/file-20200817-16-xm2iez.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/illustration-influenza-virus-cells-3d-1612792156">ffikretow/Shutterstock</a></span></figcaption></figure><p>Viruses are often termed “<a href="https://global.oup.com/academic/product/the-invisible-enemy-9780198564812?cc=gb&lang=en&">the invisible enemy</a>”. They aren’t visible with the naked eye, or even by using a standard optical microscope. So how do we know they exist or what they look like? </p>
<p>There are biochemical methods, such as the ones used to confirm COVID-19 infection, that look for evidence of genetic material from a virus. But there are also multiple different methods we use in the laboratory to “see” viruses. </p>
<p>To understand these methods, we first need to understand how small viruses actually are. Most of our cells are around 100 micrometres (0.1 millimetres) in diameter. Viruses are about 1,000 times smaller than this averaging around 150 nanometres (0.00015 millimetres).</p>
<h2>Light microscopy</h2>
<figure class="align-center ">
<img alt="Healthy human lung cells (left) compared to virus-infected cells." src="https://images.theconversation.com/files/352791/original/file-20200813-16-1sndzn6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/352791/original/file-20200813-16-1sndzn6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=223&fit=crop&dpr=1 600w, https://images.theconversation.com/files/352791/original/file-20200813-16-1sndzn6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=223&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/352791/original/file-20200813-16-1sndzn6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=223&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/352791/original/file-20200813-16-1sndzn6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=281&fit=crop&dpr=1 754w, https://images.theconversation.com/files/352791/original/file-20200813-16-1sndzn6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=281&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/352791/original/file-20200813-16-1sndzn6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=281&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Healthy human lung cells (left) compared to virus-infected cells, as seen through a standard visible light microscope (magnification 10x).</span>
<span class="attribution"><span class="source">Grace Roberts</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Standard light microscopes allow us to see our cells clearly. However, these microscopes are <a href="https://svi.nl/DiffractionLimit">limited by light itself</a> as they cannot show anything smaller than half the wavelength of visible light – and viruses are much smaller than this.</p>
<p>But we can use microscopes to see the damage viruses do to our cells. We call this “<a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1006409">cytopathic effect</a>”, and comparing infected cells to uninfected ones enables us to detect the presence of viruses in a sample.</p>
<p>Preliminary work on SARS-CoV-2 (the virus that causes COVID-19) using light microscopy <a href="https://www.biorxiv.org/content/10.1101/2020.07.14.202028v1">has revealed</a> that the virus is able to fuse infected cells together to form syncitia - large cells with multiple nuclei – an effect that has previously been observed in several other respiratory viruses. </p>
<h2>Immunofluorescence</h2>
<figure class="align-center ">
<img alt="Immunofluorescence image showing lung hairs (pink), lung cell nuclei (blue) and virus particles (green)." src="https://images.theconversation.com/files/352792/original/file-20200813-16-lr2j1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/352792/original/file-20200813-16-lr2j1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/352792/original/file-20200813-16-lr2j1a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/352792/original/file-20200813-16-lr2j1a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/352792/original/file-20200813-16-lr2j1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/352792/original/file-20200813-16-lr2j1a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/352792/original/file-20200813-16-lr2j1a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=552&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Immunofluorescence image showing lung hairs (pink), lung cell nuclei (blue) and virus particles (green).</span>
<span class="attribution"><span class="source">Grace Roberts</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>An indirect way of visualising viruses is to use antibodies (much like the ones your body makes in response to infection) to tag viruses with fluorescent molecules that give off light when they absorb certain types of radiation. We can even tag multiple things (such as virus and cellular components) with different colours so we can track more than one at the same time. </p>
<p>We can then detect the fluorescent light from the tags to see where viruses go inside our cells and what cell structures they <a href="https://jvi.asm.org/content/jvi/89/5/2931.full.pdf">interact with</a>. This allows us to investigate things such as <a href="https://aac.asm.org/content/48/7/2693.long">how drugs affect virus replication</a> or <a href="https://www.mdpi.com/2073-4409/9/2/412">how different strains of viruses behave differently</a>.</p>
<h2>Super resolution microscopy</h2>
<figure class="align-center ">
<img alt="Bone cancer cell nucleus with normal high resolution fluorescence microscopy (left) and after super resolution processing (right)." src="https://images.theconversation.com/files/352796/original/file-20200813-14-15tqg44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/352796/original/file-20200813-14-15tqg44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=434&fit=crop&dpr=1 600w, https://images.theconversation.com/files/352796/original/file-20200813-14-15tqg44.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=434&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/352796/original/file-20200813-14-15tqg44.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=434&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/352796/original/file-20200813-14-15tqg44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=545&fit=crop&dpr=1 754w, https://images.theconversation.com/files/352796/original/file-20200813-14-15tqg44.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=545&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/352796/original/file-20200813-14-15tqg44.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=545&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bone cancer cell nucleus with normal high resolution fluorescence microscopy (left) and after super resolution processing (right).</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:GFP_Superresolution_Christoph_Cremer.JPG#/media/File:GFP_Superresolution_Christoph_Cremer.JPG">Christoph Cremer/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Recent advances in fluorescent microscopy have led to the development of <a href="https://www.nature.com/articles/s41556-018-0251-8">super resolution microscopy</a>, which combines very clever physics with computational methods to produce clear images that reveal highly detailed structures in cells.</p>
<p>Using this technique for virology can pinpoint areas of an infected cell with more accuracy. For instance, it can show exactly <a href="https://retrovirology.biomedcentral.com/articles/10.1186/s12977-018-0424-3">where inside</a> the cell viruses <a href="https://pubmed.ncbi.nlm.nih.gov/30206266">are located</a>, and what specific parts of cellular machinery viruses <a href="https://febs.onlinelibrary.wiley.com/doi/10.1002/1873-3468.12186">use to replicate</a>. </p>
<h2>Electron Microscopy</h2>
<figure class="align-center ">
<img alt="Electron microscopy visualisation of SARS-CoV-2 particles" src="https://images.theconversation.com/files/352801/original/file-20200813-18-kr15l3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/352801/original/file-20200813-18-kr15l3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=239&fit=crop&dpr=1 600w, https://images.theconversation.com/files/352801/original/file-20200813-18-kr15l3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=239&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/352801/original/file-20200813-18-kr15l3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=239&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/352801/original/file-20200813-18-kr15l3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=300&fit=crop&dpr=1 754w, https://images.theconversation.com/files/352801/original/file-20200813-18-kr15l3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=300&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/352801/original/file-20200813-18-kr15l3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=300&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Electron microscopy visualisation of SARS-CoV-2 particles, approximately 150-200 nanometres in diameter.</span>
<span class="attribution"><span class="source">Liu et al</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>None of the techniques mentioned so far are able to directly visualise virus particles. That’s where electron microscopy comes in, as it can produce images at the nanometre scale. It does this by firing electrons at a sample and seeing how they interact with it. A computer then interprets this information to produce an image.</p>
<p>This enables us to visually investigate different stages of virus infection <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2013.00306/full">inside cells</a>. Electron microscopy can also be used to visualise whole virus particles, as shown in the image above. From these images, we can form 3D structures of whole virus particles by computationally assembling images of thousands of particles taken in different orientations, such as this example of a <a href="https://phil.cdc.gov/Details.aspx?pid=23312">3D EM rendering of SARS-CoV-2</a>. </p>
<p>Electron microscopy has been used for SARS-CoV-2 <a href="https://science.sciencemag.org/content/367/6483/1260">to determine</a> how the virus uses its outer “spike” protein to interact with our cells and infect them. Such studies are really useful in working out how the virus gains access to our cells so we can work out how to use drugs to block it. </p>
<p>Evaluating the structure of the exterior of virus particles is also a great tool for identifying which antibodies <a href="https://www.sciencedirect.com/science/article/pii/S0092867420302622">can neutralise a virus</a>, which can help produce more precise and effective vaccines.</p>
<h2>Crystallography</h2>
<figure class="align-center ">
<img alt="X-ray crystallographic structure of the Norwalk virus capsid" src="https://images.theconversation.com/files/353464/original/file-20200818-16-19817g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353464/original/file-20200818-16-19817g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353464/original/file-20200818-16-19817g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353464/original/file-20200818-16-19817g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353464/original/file-20200818-16-19817g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353464/original/file-20200818-16-19817g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353464/original/file-20200818-16-19817g.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">X-ray crystallographic structure of the Norwalk virus capsid.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Norwalk_Caspid.jpg">BV Prasad et al</a></span>
</figcaption>
</figure>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182643/">Crystallography</a> allows us to view structures in even more detail, at the atomic level. To do this, you need a really pure sample of virus (with no debris) suspended in solution. The liquid of the suspension is evaporated which causes crystallisation of the remaining solids (including the virus). These align in a uniform manner to form crystals that can then be exposed to X-rays. </p>
<p>A detector records the way in which the X-rays diffract (or “bounce”) from the crystallised sample, indicating where the electrons are in the sample structure. This information can then be used to construct an atomic-scale <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5629563/">3D structure of the sample</a>.</p>
<p>As with electron microscopy, crystallography can be used to determine structures of viruses, such as the spike protein <a href="https://www.nature.com/articles/s41586-020-2380-z">of SARS-CoV-2</a>. Understanding these structures, especially how they interact with our cells and antibodies informs vaccine and drug design.</p><img src="https://counter.theconversation.com/content/144363/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grace C Roberts works at Queen's University, Belfast and receives funding from The Wellcome Trust. </span></em></p>Viruses are too small to visualise with traditional microscopes.Grace C Roberts, Research Fellow in Virology, Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1390482020-05-21T15:04:12Z2020-05-21T15:04:12ZCoral reefs that glow bright neon during bleaching offer hope for recovery – new study<figure><img src="https://images.theconversation.com/files/336473/original/file-20200520-152298-10c1yx2.JPG?ixlib=rb-1.1.0&rect=0%2C211%2C3820%2C2590&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Corals glow in neon shades during a 2010 bleaching episode at Palawan, Philippines.</span> <span class="attribution"><span class="source">Ryan Goehrung/University of Washington.</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Ocean heatwaves cause vast coral bleaching events almost every year due to climate change, threatening reefs around the world. The high water temperatures stress reef building corals, causing them to eject the photosynthetic algae that reside in their tissue. Losing these brownish-coloured plant cells lets the coral’s white limestone skeleton shine through, turning reefs ghostly white. </p>
<p>But when some corals bleach, they undergo a mysterious transformation that has confounded scientists. Rather than turning white, these corals emit a range of different neon colours. Colorful bleaching, as it’s known, was covered in the documentary <a href="https://www.chasingcoral.com/">Chasing Coral</a>, which showed a whole reef <a href="https://www.google.com/maps/@-22.3116493,166.2806091,3a,75y,228.71h,56.42t/data=!3m8!1e1!3m6!1sAF1QipMWUL50QIb1bc36GfobfWrkIOkZkFXFbLLCyndU!2e10!3e12!6shttps:%2F%2Flh5.googleusercontent.com%2Fp%2FAF1QipMWUL50QIb1bc36GfobfWrkIOkZkFXFbLLCyndU%3Dw365-h260-k-no-pi-0-ya52.5-ro-0-fo100!7i7000!8i3500">turning fluorescent</a>. The <a href="https://theoceanagency.org/team">underwater photographer</a> who documented the event said: </p>
<blockquote>
<p>It was as if the corals were screaming for attention in vivid colour, trying to protect themselves from ocean heatwaves. We’d witnessed the ultimate warning that the ocean is in trouble.</p>
</blockquote>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/336477/original/file-20200520-152288-kgzcsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/336477/original/file-20200520-152288-kgzcsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/336477/original/file-20200520-152288-kgzcsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/336477/original/file-20200520-152288-kgzcsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/336477/original/file-20200520-152288-kgzcsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/336477/original/file-20200520-152288-kgzcsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/336477/original/file-20200520-152288-kgzcsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A coral glowing neon purple during a bleaching event in New Caledonia, 2016.</span>
<span class="attribution"><span class="source">Richard Vevers/The Ocean Agency</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(20)30571-6">new research</a>, we’ve finally uncovered why corals do this.</p>
<h2>Solving a coral conundrum</h2>
<p>We knew that the appearance of unusually fluorescent corals was linked to bleaching. But why didn’t all corals suddenly become more colourful? And why did they only seem to appear during certain bleaching events? Things got even stranger when we tried to expose corals in the laboratory to experimental heat stress. </p>
<p>In our first trials, instead of becoming more colourful, <a href="https://www.sciencedirect.com/science/article/pii/S0025326X1200570X?via%253Dihub">they just bleached white</a>. But after conducting more lab experiments with the help of our students <a href="https://coralreef.nus.edu.sg/elenabollati.html">Elena Bollati</a> and <a href="https://www.uts.edu.au/research-and-teaching/our-research/climate-change-cluster/our-people/research-students/rachel-alderdice">Rachel Alderdice</a>, we found an answer.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/336476/original/file-20200520-152327-ofiafr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/336476/original/file-20200520-152327-ofiafr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/336476/original/file-20200520-152327-ofiafr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/336476/original/file-20200520-152327-ofiafr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/336476/original/file-20200520-152327-ofiafr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/336476/original/file-20200520-152327-ofiafr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/336476/original/file-20200520-152327-ofiafr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The coral animal has lost its algae and bleached white. The coral is still alive and has the potential to recover.</span>
<span class="attribution"><span class="source">Cecilia D'Angelo & Jörg Wiedenmann / University of Southampton</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In healthy corals, much of the sunlight is absorbed by the photosynthetic pigments of the algae. When corals lose their algae due to stress, the excess light travels back and forth inside the coral tissue, <a href="https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.4319/lo.2005.50.4.1025">reflected by the white skeleton</a>. The algae inside coral can recover after bleaching, once conditions return to normal. But when the coral interior is lit up brightly like this, it can be very <a href="https://bmcecol.biomedcentral.com/articles/10.1186/s12898-016-0061-4">stressful for the algae</a>, potentially delaying or even preventing their return.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/revealed-why-some-corals-are-more-colourful-than-others-36866">Revealed: why some corals are more colourful than others</a>
</strong>
</em>
</p>
<hr>
<p>If the coral cells can still carry out at least some of their normal functions during bleaching, the increased internal light levels boost the production of <a href="https://link.springer.com/article/10.1007/s00338-012-0994-9">colourful pigments</a> which protect the coral from light damage, forming a kind of sunscreen layer that allows algae to return. As the recovering algae start absorbing light for photosynthesis again, light levels inside the coral drop, and so the coral stops producing as much of these colourful pigments.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/MuGZCwam4Js?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>But it’s not just heat stress that can cause colourful bleaching. Corals and their algae are very sensitive to changes in <a href="https://doi.org/10.1016/j.cosust.2013.11.029">nutrient levels in their environment</a>. When there’s too little phosphorous or too much nitrogen in the water – something that can happen when <a href="https://theconversation.com/sponge-v-coral-overfishing-brings-caribbean-reefs-to-the-brink-of-a-new-battle-40927">fertiliser</a> runs off from farmland into the ocean – strong colourful bleaching can occur.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/336483/original/file-20200520-152284-1bobeo1.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"></a>
<figcaption>
<span class="caption">The internal changes that allow colourful bleaching to occur.</span>
<span class="attribution"><span class="source">Jörg Wiedenmann, Elena Bollati & Cecilia D’Angelo/University of Southampton, Palawan colourful bleaching image by Ryan Goehrung/University of Washington</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A brighter future for reefs</h2>
<p>Using satellite data, we reconstructed the temperature profiles for known colourful bleaching events. We saw that they tend to occur after brief or mild episodes of heat stress. When corals are exposed to severe or prolonged temperature extremes, they tend to bleach white. That’s why we only see bright neon colours in particular bleaching episodes, when conditions are just right.</p>
<p>Different members of the coral community can display different colours during these events, while some species don’t produce these colourful protective pigments at all. But even within coral species, there can be different <a href="https://theconversation.com/revealed-why-some-corals-are-more-colourful-than-others-36866">colour variants</a> that result from differences in their <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/mec.13041">genetic makeup</a>.</p>
<p>These variants have evolved to give species <a href="https://www.frontiersin.org/articles/10.3389/fmars.2018.00011/full">different strategies</a> to deal with light, depending on where they grow on the reef. For corals in shallower water it’s beneficial to invest a lot of energy in producing the colourful sunscreen. At greater depths or in shaded areas where light stress is lower, corals that produce less of the protective pigment are better off as they can save their energy for other useful purposes. Even so, these different variants often occur side-by-side, which is why some corals bleach colourful while their neighbours turn white.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/336481/original/file-20200520-152292-11aoipv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/336481/original/file-20200520-152292-11aoipv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=411&fit=crop&dpr=1 600w, https://images.theconversation.com/files/336481/original/file-20200520-152292-11aoipv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=411&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/336481/original/file-20200520-152292-11aoipv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=411&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/336481/original/file-20200520-152292-11aoipv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=516&fit=crop&dpr=1 754w, https://images.theconversation.com/files/336481/original/file-20200520-152292-11aoipv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=516&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/336481/original/file-20200520-152292-11aoipv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=516&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Colourful bleaching versus white bleaching on the Great Barrier Reef in 2010.</span>
<span class="attribution"><span class="source">Darren Coker / JCU Townsville</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The good news is that colourful bleached reefs seem more likely to recover than corals that bleach white, since they tend to appear when heat stress isn’t so severe and the colourful pigments themselves offer protection. Reports suggest that colourful bleaching occurred on some parts of the Great Barrier Reef in March and April 2020, so some patches of the world’s largest reef system may have better prospects for recovery after the recent bleaching.</p>
<p>Now that we know that nutrient levels can affect colourful bleaching too, we can more easily pinpoint cases where heat stress might have been aggravated by <a href="https://doi.org/10.1016/j.cosust.2013.11.029">poor water quality</a>. This can be managed locally, whereas the ocean heat waves caused by climate change will need global leadership. Together, these actions can secure a future for coral reefs.</p><img src="https://counter.theconversation.com/content/139048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jörg Wiedenmann receives funding from Deutsche Forschungsgemeinschaft, Natural Environment Research Council and European Research Council.</span></em></p><p class="fine-print"><em><span>Cecilia D'Angelo receives funding from Deutsche Forschungsgemeinschaft, Natural Environment Research Council and European Research Council.</span></em></p>While most corals turn ghostly white when they bleach, some turn neon purple. Scientists were baffled – until now.Jörg Wiedenmann, Head of the Coral Reef Laboratory, University of SouthamptonCecilia D'Angelo, Senior Research Fellow, Coral Reef Laboratory, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/924382018-04-10T19:56:23Z2018-04-10T19:56:23ZCurious Kids: How does glow in the dark paint work?<figure><img src="https://images.theconversation.com/files/209656/original/file-20180309-30954-f1bl33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">While some things glow all the time, glow-in-the-dark paint must be 'told to glow' - just like a phone needs to be charged or it won't work.</span> <span class="attribution"><span class="source">Mai Lam/The Conversation NY-BD-CC</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em></p>
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<p><strong>How does glow in the dark paint work? – Roman, age 5, Katoomba.</strong></p>
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<p>To answer your question, we need to talk about light. This is not an easy thing to do. About 100 years ago, the world’s smartest scientists even argued about what light really is. And they argued for many years. </p>
<p>Light is actually a bunch of tiny things that scientists call “photons”. These little things can travel unbelievably quickly.</p>
<p>How quickly? Well, imagine this: photons can go around the entire world more than seven times in just one second.</p>
<p>When these photons reach our eyes, we see them as light. The more photons there are, the brighter the light. </p>
<p>Photons can come in all the colours of the rainbow. They also hold energy which can turn into heat. This is why it feels warm when the sun shines. </p>
<p>But, not all light is the same. Blue and violet photons both have more energy than red ones, for example.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-why-does-rain-only-come-from-grey-clouds-90325">Curious Kids: why does rain only come from grey clouds?</a>
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<h2>Invisible light</h2>
<p>Now here is a weird thing: there are some types of light that are invisible! </p>
<p>For example, ultraviolet (UV) light, which has even more energy than blue and violet light, is invisible.</p>
<p>Sunlight contains some of this powerful UV light. Because it has so much energy, it can cause a lot of damage, like sunburn, if you get too much of it on your skin.</p>
<p>Another invisible type of light is infrared light. Infrared means “less than red”, so this light has even less energy than red light.</p>
<h2>Making paint glow</h2>
<p>Many light sources, like the Sun or an old light bulb in your bathroom, glow because they are really hot. Normal glowing, like that of the Sun and a light bulb, requires objects to be really hot for us to see it. </p>
<p>As you already know, you can see glow-in-the-dark paint, but if you touch it, it is just as cold as the bedroom wall. So, the glowing of the paint must be different to the glowing of a light bulb. </p>
<p>The paint has a special kind of glowing called “luminescence” and it can only be created from a few types of material. One such material is what scientists call “luminescent phosphors”, and this is what makes your paint glow. Scientists make luminescent phosphors in the lab by mixing special chemicals together, and then add them to the paint. The paint is then sold to factories and manufacturers who put it on toys, stickers, and even inside colouring pens.</p>
<p>While some things glow all the time, like the sun, glow-in-the-dark paint must be “told to glow”. Just like your parents need to charge their phones every night to make them work, these materials need to be “charged” before they start glowing. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-is-x-ray-vision-possible-90393">Curious Kids: Is x-ray vision possible?</a>
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<p>In fact, the charging of your glow-in-the-dark paint is done by other types of light. The invisible UV light with lots of energy can charge the special phosphors in your paint and make it glow in your bedroom at night. </p>
<p>There are different types of glow-in-the-dark paint. One type can be charged during the day and can glow for hours in the dark at night. The charging that happens during the day, for example by sunlight, is stored in the paint for some time, just like in the battery of a phone. </p>
<p>This type of paint is called phosphorescent. The other type, called fluorescent paint, only glows while an invisible UV light is turned on to charge it.</p>
<p>You might have heard that some animals can glow. Here’s a video all about that:</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/jp-jYVktx7s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
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<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/92438/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thorsten Trupke 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>You can see glow-in-the dark paint, but if you touch it, it is just as cold as the bedroom wall. So the glowing of the paint is different to the glowing of a light bulb.Thorsten Trupke, Professor of Photovoltaic and Renewable Energy Engineering, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/746022017-03-30T06:13:18Z2017-03-30T06:13:18ZThe world’s first glow-in-the-dark frog found in Argentina<figure><img src="https://images.theconversation.com/files/162094/original/image-20170322-31217-183kp0s.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A male Hypsiboas punctatus frog in daylight.</span> <span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/c/ca/Hypsiboas_punctatus_Peru_02.JPG">Erfil/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Scientists in Argentina have discovered a frog that glows in moonlight and at twilight. Fluorescence in terrestrial environments had previously only been traced to a few species of insects and birds and had never been scientifically reported in any of the world’s 7,000-plus amphibian species.</p>
<p>A team of herpetologists made the <a href="http://www.nature.com/news/first-fluorescent-frog-found-1.21616">headline-grabbing discovery</a> in the outskirts of the city of Santa Fe, Argentina, while collecting frogs to research the biochemical <em>cloricia</em> in amphibians. They sought out the polka-dot tree frog (<em>Hypsiboas punctatus</em>), a species found throughout South America, because its translucent skin allows the <a href="https://en.wikipedia.org/wiki/Polka-dot_tree_frog">accumulation of biliverdin</a> (a blue-green bile pigment) to be seen with the naked eye.</p>
<p>But when they shone a UVA light on the frogs, they did not see the faint red biliverdin emission they had anticipated. Rather, what they saw was a bright and beautiful cyan fluorescence. So luminous were the frogs that under the black light they glowed in the dark, helping the scientists locate specimens. This fluorescence was present in all of the 100-plus polka-dot tree frogs collected.</p>
<p>The team included researchers from the <a href="http://www.macn.secyt.gov.ar/cont_Gral/home.php">Bernardino Rivadavia Argentine Museum of Natural Sciences-CONICET</a>, the <a href="http://exactas.uba.ar/">University of Buenos Aires</a>, the <a href="http://www.leloir.org.ar/en/">Instituto Leloir Foundation</a> and <a href="http://www.inquimae.fcen.uba.ar/">INQUIMAE-CONICET</a> in Argentina and Brazil’s <a href="http://fcfrp.usp.br/pg/pcf/en/">University of São Paulo Faculty of Pharmaceutical Sciences of Ribeirão Preto</a>.</p>
<h2>Luminous in the moonlight</h2>
<p>The polka-dot tree frog’s translucent skin appears to glow because it allows a high level of transmission of light in the green and red parts of the electromagnetic spectrum, while blocking transmission of blue light.</p>
<p>The peculiar cyan fluorescence, which we found originated in its skin glands and lymph nodes, belongs to a family of derivatives of the molecule dihydroisoquinolinone. The compounds were named <a href="http://dx.doi.org/10.1073/pnas.1701053114">“hyloins”</a>, after the amphibian family Hylidae, to which the tree frog belongs.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/162274/original/image-20170323-4930-1rvlcpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/162274/original/image-20170323-4930-1rvlcpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162274/original/image-20170323-4930-1rvlcpu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162274/original/image-20170323-4930-1rvlcpu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162274/original/image-20170323-4930-1rvlcpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162274/original/image-20170323-4930-1rvlcpu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162274/original/image-20170323-4930-1rvlcpu.jpg?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">
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<span class="caption">The polka-dot tree frog seen in daylight, above, and glowing under black light, below.</span>
<span class="attribution"><span class="source">Julián Faivovich and Carlos Taboada</span>, <span class="license">Author provided</span></span>
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<p>Fluorescence can be an important biosignal for visual communication, helping these frogs locate each other. The perceived brightness depends on several factors: the proportion of photons arising from fluorescence compared to those reflected by the animal; the spectral lighting conditions of the environment where the amphibians live; and the sensitivity of frogs’ eyes to different colours.</p>
<p>In the case of <em>Hypsiboas punctatus</em>, we found that under twilight-nocturnal conditions, between 18% and 30% of all the light (photons) emanating from the frog’s skin were florescent. That’s a substantial proportion, enough to add significant fluorescence to the typical green (in daylight) colouration of the frog, enhancing its visibility.</p>
<p>Finding fluorescence in a land animal is particularly interesting because it has been <a href="http://pubs.rsc.org/-/content/articlelanding/2015/pp/c5pp00122f/unauth#!divAbstract">generally considered irrelevant</a> but for its presence in some insects (spiders, scorpions, beetles, butterflies, moths, dragonflies, millipedes) and in two avian species, parrots and parrotlets. In parrotlets, differences in feather fluorescence between sexes <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.2012.00931.x/abstract">have been found to serve</a> a function in mating and attraction.</p>
<p>With the polka-dot tree frog, we expect that its fluorescence plays a role in inter-species visual communication (because it matches the sensitivity of the frogs’ eyes photoreceptors for blue and green). We do not believe that it has any relevance to mating, as florescence does not seem to differ between females and males.</p>
<h2>What else glows?</h2>
<p>The discovery of fluorescence in frogs – a species previously unknown to exhibit it – has renewed interest in searching for other glow-in-the-dark amphibians.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/162262/original/image-20170323-4924-ntlsn0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/162262/original/image-20170323-4924-ntlsn0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=500&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162262/original/image-20170323-4924-ntlsn0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=500&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162262/original/image-20170323-4924-ntlsn0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=500&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162262/original/image-20170323-4924-ntlsn0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=628&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162262/original/image-20170323-4924-ntlsn0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=628&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162262/original/image-20170323-4924-ntlsn0.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">Beetles also display fluorescence.</span>
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</figure>
<p>The finding also opens additional avenues for future research. A more detailed study on the spectral sensitivity of the eye photoreceptors of <em>Hypsiboas punctatus</em>, for example, would help us calculate the amount of light reaching each of the polka-dot tree frog’s photoreceptors and better understand the species’ visual perception.</p>
<p>We are also interested in evaluating the photophysical properties of the purified free fluorophores found in this study, including their chemical and biochemical makeup. They could potentially be used as fluorescent markers or labels in molecular biology or biotechnology, allowing <a href="https://en.wikipedia.org/wiki/Fluorescent_tag">microscopic detection of biomolecules</a>.</p>
<p>Finally, this discovery has given scientists a strong hint for the answer to an important question in biophotophysical research: does naturally occurring fluorescence act as a biosignal, or is it simply a non-functional outcome of certain pigments’ chemical structure?</p>
<p>The polka-dot tree frog’s moonlight glow suggests strongly that, yes, fluorescence matters.</p>
<hr>
<p><em>Scientists involved in this work were: Carlos Taboada (Bernardino Rivadavia Argentina Museum of Natural Sciences-CONICET and the University of Buenos Aires, INQUIMAE-CONICET); Andrés E. Brunetti (Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo); Federico N. Pedron (University of Buenos Aires, INQUIMAE-CONICET and the Department of Inorganic, Analytic and Physical Chemical Chemistry, FCEN); Fausto Carnevale Neto (Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo); Darío A. Estrin (University of Buenos Aires, INQUIMAE-CONICET and the Department of Inorganic, Analytic and Physical Chemical Chemistry, FCEN); Sara E. Bari (University of Buenos Aires, INQUIMAE-CONICET); Lucía B. Chemes (Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET); Norberto Peporine Lopes (Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo); María G. Lagorio (University of Buenos Aires, INQUIMAE-CONICET and the Department of Inorganic, Analytic and Physical Chemical Chemistry, FCEN); and Julián Faivovich (Bernardino Rivadavia Argentina Museum of Natural Sciences-CONICET and University of Buenos Aires Department of Biodiversity and Biologial Experimentation, FCEN).</em></p><img src="https://counter.theconversation.com/content/74602/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>María Gabriela Lagorio 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>Scientists in Argentina have discovered a frog that glows in moonlight and at twilight.María Gabriela Lagorio, Researcher and Professor, Bioespectroscopy and Biophotochemistry, Universidad de Buenos AiresLicensed as Creative Commons – attribution, no derivatives.