This Arctic fish has gills stuffed with antifreeze, scientists find : ScienceAlert

Bathing in bitterly cold water between the turquoise arms of a remote Greenland iceberg, researchers caught an arctic fish with a body that is highly tolerant of freezing temperatures.

Currents regularly drop below zero degrees Celsius off East Greenland, where the juvenile was caught.

These frigid temperatures are enough to freeze the blood of tropical-accustomed fish. Many antifreeze proteins flow through blood vessels.

When researchers sequenced the RNA of Arctic fish, they found that the variegated snail (Liparis Gibbs), they found that the seeds were packed in their gills with antifreeze protein.

Bifilo Vitro Gruber from the City University of New York.

“We already knew that these little snails that live in very cold water produce antifreeze proteins, but how tightly packed those proteins are and how much effort goes into making these proteins. I wasn’t aware of what was going on.”

The fish in question are L. Gibbs, Also known as the polka-dotted snail, it is named for the black flecks found all over its brown, flabby body.

On the surface, it is a fairly unremarkable species. But what’s inside is full of surprises.

A bird's eye view of an iceberg in Greenland.
The Greenland iceberg where the snail was found. (Peter Clough)

In 2019, variegated snails were spotted glowing green and red. This is the first Arctic fish reported to be biofluorescent and the first instance of a single species exhibiting her bichromatic fluorescence.

Now, RNA sequencing has revealed another snail secret.

Among all the thousands of transcripts sequenced in Arctic species, researchers found several that encode antifreeze-like proteins. They were all highly expressed.

In fact, one transcript was the most highly expressed in the bundle, well above the top 1%.

In the field of genetics, a “transcript” is an RNA copy of a portion of DNA. It gives the cell instructions on how to produce a particular protein.

Such high expression of antifreeze transcripts suggests that snails place importance on these proteins. They are probably important for surviving in subzero temperatures.

Ice-binding antifreeze proteins have been found in many other polar and subpolar fish, as well as some reptiles, insects, and plants.

In fish, these liver-produced proteins are thought to prevent ice particles from becoming too large or accumulating and clogging inside cells and fluids.

The most highly expressed antifreeze-like protein in snails is relatively weak compared to other proteins Antifreeze type Although it is a protein, it may play an important role in maintaining the biological functions of fish.

A mixture of weaker and stronger proteins can actually work together to provide the temperature resistance a snail needs to live in such bitter water.

For example, some antifreeze proteins may not be strong enough to stop the growth of ice crystals in the blood, but they help transport unsaturated lipids, which require specific temperatures as they move through blood vessels. There is a possibility.

As such, the authors say their findings in snails raise the possibility that “weak or combined antifreeze effects may be beneficial” for Arctic fish.

At least it’s useful now.

“Since the mid-20th century, temperatures have warmed twice as fast in the Arctic as in mid-latitudes, and if Arctic sea ice continues to decline at the current rate, we project that the Arctic Ocean will be nearly ice-free in summer. Some studies will do so within the next 30 years,” warns co-author John Sparks, curator of the American Museum of Natural History.

“The Arctic Ocean does not support a high degree of fish species diversity, and our research suggests that as ocean temperatures become increasingly warmer, this snail-like ice-dwelling expert has previously predicted that these more We hypothesize that we may encounter increased competition from more temperate species that could not survive in high northern latitudes.”

That lone Greenland iceberg may not exist for very long. Who knows what will become of the fish swimming in its shadow.

This research evolutionary bioinformatics.

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