Fish 'crammed full' of antifreeze protein found in iceberg habitats off Greenland

New research based on an expedition to icy waters off Greenland reveals high levels of antifreeze protein in a species of tiny snail, highlighting the importance of this unique adaptation to life in sub-zero temperatures. The study, led by scientists from the American Museum of All-natural History and the City College of New York (CUNY), and published today in the journal Evolutionary Bioinformatics, also warns that warming ocean temperatures in the Arctic could pose a threat to these highly specialized species. fish.

“Similar to how the antifreeze in your car keeps the water in your radiator from freezing in cold weather, some animals have developed amazing devices that prevent them from freezing, such as antifreeze proteins, which prevent the formation of ice crystals,” said David Gruber, a research associate at the Museum and a distinguished professor of biology at CUNY’s Baruch Faculty. “We already knew that this little snail, which lives in extremely cold waters, produced antifreeze proteins, but we didn’t realize just how full of these proteins it is – and how much effort it goes into making. these proteins.”

The freezing waters of the polar oceans are an extreme environment for maritime life, limiting inhabitants to those with mechanisms to deal with freezing temperatures. Unlike some species of reptiles and insects, fish cannot survive even partial freezing of their body fluids. They therefore depend on antifreeze proteins, made mainly in the liver, to prevent the formation of large grains of ice inside their cells and body fluids. The ability of fish to make these specialized proteins was discovered almost 50 years ago, and scientists have since determined that antifreeze proteins are made from five families of different genes.

Gruber and co-author John Sparks, curator in the Museum’s Department of Ichthyology, decided to investigate the antifreeze proteins of juvenile variegated snailfish, Liparis gibbus, after encountering an exceptional ability distinct from the small fish – biofluorescence. In 2019, as part of a Constantine. The S. Niarchos, Sparks, and Gruber expedition were exploring iceberg habitats off the coast of eastern Greenland when they found a young variegated snail glowing green and red. Biofluorescence, the ability to convert blue light to green, red or yellow light, is uncommon in arctic fish – where there are long periods of darkness – and the snail remains the only polar fish reported as biofluorescent.

After further investigation of the biofluorescent properties of snails, researchers discovered two different types of gene families encoding antifreeze proteins. Snail genes have the highest expression levels of antifreeze proteins ever observed, underscoring their relevance for the survival of these animals and sending a warning signal about how they might behave under environmental conditions of warming.

“Since the middle of the 20th century, temperatures have risen twice as fast in the Arctic than mid-latitudes and some studies predict that if Arctic sea ice decline continues at this current rate, in summer the Arctic Ocean will be largely ice-free. in the next three decades,” Sparks said. “Arctic seas do not support a high diversity of fish species, and our study hypothesizes that with increasingly warm ocean temperatures, ice specialists such as this snail may encounter competition. increased by more temperate species that were previously unable to survive in these higher northern areas. latitudes.”

Other authors of this study include John Burns, American Museum of Organic Heritage and the Bigelow Laboratory for Ocean Sciences Jean Gaffney, CUNY and Mercer Brugler, American Museum of Natural History and University of South Carolina at Beaufort.

This research was generously supported by the Stavros Niarchos Foundation thanks to an AMNH Constantine S. Niarchos Expedition grant.



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