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Go to http://Brilliant.org/SciShow to try their Scientific Thinking course. The first 200 subscribers get 20% off an annual Premium subscription.

Bivalves—animals like mussels, clams and oysters—might be a more familiar sight in a restaurant than a lab. But it turns out that studying them might help us learn more about our own health.

Hosted by: Hank Green

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Sources:
https://www.nature.com/articles/nrmicro1750
https://www.nature.com/scitable/definition/model-organism-model-genetic-organism-139/
https://www.ncbi.nlm.nih.gov/books/NBK21070/
https://www.nature.com/articles/nature18599
https://www.cell.com/fulltext/S0092-8674%2815%2900243-3
https://www.sciencedirect.com/science/article/pii/S0145305X1830301X
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Image Sources:
https://www.istockphoto.com/photo/raw-blue-mussels-on-a-white-background-gm645002008-117034371
https://www.istockphoto.com/photo/raw-clam-gm499197994-80080063
https://www.istockphoto.com/photo/fresh-oyster-isolated-gm1076323920-288234381
https://www.istockphoto.com/photo/portrait-of-a-ferret-looking-to-the-camera-gm538876982-95937877
https://www.istockphoto.com/photo/toxocara-canis-second-stage-larvae-hatch-from-eggs-gm942368788-257164522
https://www.istockphoto.com/photo/mediterranean-purple-sea-urchin-sphaerechinus-granularis-gm1155299359-314475157
https://commons.wikimedia.org/wiki/File:Alexandrium_catenella.jpg
https://commons.wikimedia.org/wiki/File:PDB_1p0l_EBI.jpg
https://www.istockphoto.com/photo/pile-of-clams-gm155013393-16875744
https://www.istockphoto.com/photo/mother-of-pearl-luxury-background-gm594911996-101975579
https://www.istockphoto.com/photo/isolated-shot-of-abalone-shell-on-white-background-gm1197971034-342210295
https://www.istockphoto.com/photo/luxury-nacre-seashell-background-texture-close-up-gm1018041166-273704142
https://www.istockphoto.com/vector/oysters-in-the-half-shell-icon-set-gm464423952-59019314
https://www.istockphoto.com/photo/x-ray-of-knee-gm1173941778-326273836
https://www.istockphoto.com/photo/colony-of-mussels-in-the-colorful-algae-and-water-plants-in-the-shallow-water-gm1159475925-317061450
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Go to Brilliant.org/SciShow to check out their course on Scientific Thinking. [♪ INTRO]. Think of animals traditionally used in scientific research, and you probably think: rats, mice, guinea pigs, fruit flies...

But there might be a new player in town, and it’s one we’re more used to seeing at the raw bar than at the lab bench: bivalves like mussels, clams, and oysters. Animals that researchers use to help find answers to basic biological questions are known as model organisms. They’re generally chosen because their biology is well known and they’re easy to care for in the lab.

Not only that though, we usually pick specific animals because they resemble us in some key way, so they make good models to help us understand more about ourselves. There are already a few well-established model organisms that might seem like bizarre choices compared to mice and rats: things like ferrets, nematodes, and even sea urchins. Bivalves may soon make this shortlist of favorite model organisms.

They meet the requirement of being easy to care for — you don’t even need a supply of ocean water. And it turns out there’s a lot they can tell us about ourselves. In the last decade, researchers have been working hard to learn more about them, and apply what they’re learning to improve our own health and wellbeing.

For example, bivalves have the potential to teach us a lot about how immunity works. The ocean is positively crawling with viruses and other microbes. And it’s not like bivalves’ shells keep the water out: water supplies the oxygen and nutrients they need to survive.

Which means they are constantly encountering disease-causing pathogens — for example, the microorganism that causes paralytic shellfish poisoning, which you do not want to get! — but the bivalves themselves don’t seem to get sick. And they do it without the help of antibodies. Their immune systems can’t make them.

The adaptive immune system, which produces antibodies, is something only vertebrates have. Instead, as a part of their immune system, invertebrates like bivalves produce chains of amino acids that have the ability to kill microbes — earning them the name antimicrobial peptides, or AMPs. These seem to be at least partly responsible for why bivalves can withstand being constantly bathed in disease-causing microorganisms.

This is especially true for mussel: they have a huge variety of AMPs, even compared to other bivalves, which allows them to fend off many different pathogens and diseases. Pharmaceutical companies are especially interested in studying mussel AMPs, in the hopes that they might make good alternatives to existing antibiotics, which is really important because we’re dealing a lot with antibiotic resistance right now. Additionally, learning more about the immune system strategies that have evolved in bivalves could inspire new treatment options for all kinds of human diseases.

Speaking of immunity, several types of bivalves — including clams, mussels and cockles — are subject to a contagious form of cancer. The cancer that they get typically spreads between animals of a single species — but as researchers have dug deeper, they’ve found that it’s also been able to spread between species. In the past, contagious cancers were considered a fluke of nature, but now researchers believe they could be more widespread than they originally thought.

The discovery of this type of contagious cancer has inspired scientists to look into it as a model for human cancers. They hope that understanding more about how it spreads between these animals can help us understand more about how cancer spreads within our own bodies. Finally, despite the obvious cosmetic differences, the way bivalves form their shells can teach us a lot about how our bones are formed and repaired.

Nacre in particular is of interest to researchers. That’s the iridescent layer lining bivalve shells — the stuff that oysters use to make pearls. Nacre from oyster shells has been used to help with the mineralization and growth of bones in sheep, mice, rats and humans.

Basically, nacre stimulates bone-forming cells in the body, activating the process by which bones grow and then fill in with minerals. Along these same lines, it’s also been found to delay osteoporosis in lab rats, through the activation of bone-forming cells. Nacre may also help make bone grafts more compatible with our bodies and immune systems.

Along these same lines, oysters have become a model to study tissue implants, due to their pearl-growing abilities. The pearl industry makes natural pearls by inserting a piece of tissue from a donor oyster, along with a nucleus for the pearl to form around, into the gonad of a recipient oyster. This means that, much like a tissue implant, the two genetically distinct tissues have to play nice.

But while implants are often rejected by the recipient, this is not the case in oysters. Understanding more about these processes will help us improve our implant and bone graft procedures to increase their success rate and decrease the potential for rejection. Bivalves are already being used as a model system in a lot of research, but they’re not yet as established as model organisms like mice, rats, and fruit flies.

These creatures have extremely rich genomes, as they’ve evolved in an aquatic environment with exposure to a lot of different environmental conditions. We’ve only begun to scratch the surface when it comes to understanding their genetics, which means there is lots of hidden potential for innovating and improving upon our understanding of human health. Model organisms are a huge part of how biology is done.

If you’re interested in even more insight into how scientific inquiry works, you might like Brilliant’s course Scientific Thinking. It’s designed to introduce you to the laws of physics without the number crunching, instead demonstrating principles through puzzles. And there are tons more courses on Brilliant, covering math, science, engineering, and computer science.

Right now, the first 200 people to sign up at Brilliant.org/SciShow will get 20% off an annual Premium subscription. So check it out if you’re interested — and thank you for your support. [♪ OUTRO].