The variegated snailfish is packed with naturally occurring antifreeze proteins at previously unseen levels that help it survive in subzero water, according to new research. The snailfish, known as Liparis gibbus, is also distinctive thanks to biofluorescence, which makes it glow green and red.
Study authors David Gruber and John Sparks, both studies scientists from the American Museum of Natural History in New York City, were at the Constantine S. Niarchos Scientific Expedition in 2019 when they spotted a glowing snailfish off the coast of East Greenland.
Biofluorescence occurs when animals have the ability to convert blue light into green, red or yellow light. This trait is incredibly rare in Arctic fish, which live in long periods of darkness. So far, the pied snailfish is the only known Arctic fish to have this glow.
Gruber and Sparks collected a juvenile snailfish only about 1.9 centimeters long — about the size of a fingernail — compared to an adult’s average 11.4 centimeters in length.
The scientists wanted to learn more about the snailfish’s biofluorescent properties when they discovered something else in the fish’s genetics: the highest expression levels of antifreeze proteins ever seen.
“Just as antifreeze in your car keeps the water in your radiator from freezing at low temperatures, some animals have developed amazing machines that prevent them from freezing, such as antifreeze proteins, which prevent the formation of ice crystals,” says Gruber, a researcher. researcher associate at the American Museum of Natural History and distinguished professor of biology at the Baruch College of the City University of New York, in a statement.
“We already knew that this little snail, which lives in extremely cold water, produced antifreeze proteins, but we didn’t realize how chock-full of those proteins it is — and how much effort it took to make these proteins.”
However, as Arctic waters continue to warm as a result of the climate crisis, the future of the variegated snailfish, with its remarkable adaptation to the cold, is uncertain. said study co-author John Burns, a senior research scientist at the Bigelow Laboratory for Ocean Sciences in East Boothbay, Maine.
Polar oceans are extreme environments for marine life, and only creatures that have adapted to live within freezing temperatures can survive there.
Some species of insects and reptiles can survive if their bodily fluids are partially frozen, but fish can’t. Antifreeze proteins, which are largely produced in the liver, prevent the formation of large ice granules in their cells and body fluids.
Nearly 50 years ago, scientists first discovered antifreeze proteins in fish. Researchers traced the proteins to five different genetic families.
The snailfish is particularly intriguing because it has two different types of gene families that code for the antifreeze proteins: type I and type IV.
“The genes encoding type I antifreeze proteins are likely recent additions to the fish genome and may be actively expanding into additional copies,” Burns said. “It’s like seeing evolution in action.”
The fact that the scientists discovered so many genetic details in a juvenile snailfish captures what happens as the fish grows and develops, Burns said.
“We see that in addition to growth, these juvenile fish also need to invest heavily to protect themselves from freezing,” Burns said. “The amount of RNA the fish makes for protection against frostbite matches what it invests in basic cellular machinery, the stuff that makes its cells in the first place.”
Until now, scientists do not know whether there is a connection between the biofluorescent and antifreeze proteins.
But warming temperatures in the Arctic could pose a threat to the creatures that have adapted to survive there — meaning all the energy they put into protecting them from frostbite is wasted, Burns said.
Some scientists predict that if Arctic sea ice continues to decline at its current rate, the Arctic will be ice-free within the next three decades, the study authors said.
“Arctic seas do not support great diversity of fish species, and our study hypothesizes that with increasingly warming oceanic temperatures, ice-dwelling specialists such as this snailfish may face more competition from more temperate species that were previously unable to survive in these higher northern latitudes.” Sparks, curator of the American Museum of Natural History’s division of ichthyology and professor at the museum’s Richard Gilder Graduate School, said in a statement.
Knowing more about antifreeze proteins will help scientists translate their findings into biotech applications, such as protecting crops from frost or better determining the freezing properties of meat, Burns said.