Investigation of vulnerable Antarctic fish recognized for distinguished scholarship

Fish that thrive in the ultracold waters of the Southern Ocean are the "canary in the coal mine" of 21^st century climate change. Species like the Antarctic emerald rockcod live in an environment that is consistently at or below 0° Celsius (32° Fahrenheit)-but raise the water temperature just a few degrees and many of them perish.

A study led by Washington State University biologist Wes Dowd has filled an important information gap in understanding how the rockcod evolved and how it may have lost its ability to respond to heat stress. The recently published findings were honored for distinguished scholarship by the American Physiological Society.

Most organisms have developed a protein-based heat stress response: when the temperature gets too warm, they produce specific proteins that help reduce the potential of lethal cellular damage. Not so with the rockcod.

"The Antarctic emerald rockcod is a highly sensitive stenothermal vertebrate, which is a fancy way of saying they can only survive in a very narrow range of water temperature." said Dowd.

The rockcod is both commercially fished and a key food source for Emperor penguins and seals. In order for it to survive the current warming trend of the waters around Antarctica, its limited heat stress response will need to evolve.

"To better forecast their potential to do that, we first need to understand the kinds of evolutionary changes that brought them to their current state," said Dowd.

In the study, researchers measured expression patterns for thousands of proteins in gill, kidney, and brain tissue across a range of temperature exposure conditions which confirmed the absence of a typical coordinated cellular response to heat stress. This vast new data set helps bridge the knowledge gap between the fish's DNA and its ability to function in icy waters.

Dowd, an associate professor in the WSU School of Biological Sciences, and his colleague, Dietmar Kültz at the University of California Davis, propose that a disruption in the genomic pathway which usually regulates protein expression during times of stress might explain why the fish have lost the ability to respond to temperature change. Additional studies of the genetic variation in similar species and the functional nature of their genomic changes will provide a deeper understanding of their adaptation to extreme cold.

The paper, "Lost in translation? Evidence for a muted proteomic response to thermal stress in a stenothermal Antarctic fish and possible evolutionary mechanisms", is available in the November issue of Physiological Genomics.