How fish survive in freezing Antarctica waters

Cold logic: Co-author Christin (Credit: University of Illinois)scientists have found how a fish species survives the freezing Antarctic waters. The Antarctic notothenioids produce an "antifreeze protein" that keeps their body fluids from turning into crystals.

The study analysed tissue from notothenioids and found the pancreas and stomach are the main sources of fish antifreeze -- a protein called afgp for short. The study appeared in the June 19 online edition of the Proceedings of the National Academy of Sciences. Though afgp was discovered decades ago, scientists didn't know how or in which organ the fish produced it. For some years, it has been suggested that afgp was formed in the liver, in part because the organ is a factory for blood proteins. But subsequent studies had trouble tracking afgp to the liver.

The evolution of afgp, the researchers write, was probably driven by the need to prevent the intestinal fluid from freezing, but has since allowed notothenioids to survive where many animals dare not swim.