Meeting Abstract
The extremely cold-adapted fishes of the Southern Ocean possess some of the lowest upper thermal thresholds of any species. These fishes have evolved in the sub-zero waters of Antarctica for millions of years and possess profoundly cold-dependent physiologies. Some species have lost the traditional heat shock response but they nevertheless can respond to heat via modification of the transcriptome. It is clear that stenothermal fishes and eurythermal fishes differ in their response to temperature at the transcriptomic level. Many of the genes that vary in expression during thermal stress in cold-adapted fishes are related to the broad cellular stress response, a set of stress-related processes potentially including cell cycle arrest and/or apoptosis. Here, molecular chaperoning capacity was quantified in heat-shocked Antarctic fishes with different thermal tolerances. In addition, pro-apoptotic proteins and markers of cell cycle progression were measured. Taken together, these studies indicate that even relatively mild heat exposures (2°C) can cause apoptosis in these cold-adapted and environmentally sensitive species. To our knowledge, this is the lowest upper thermal threshold for the initiation of apoptosis in any known species. The research was funded by the National Science Foundation’s Office of Polar Programs.
