Examination of ‘Heat-Hardening' in Channel Catfish

Heat stress initiates a suite of cellular responses across a wide range of plant an animal phyla. It is believed that the response, in aggregate, is adaptive and that by exposing animals to heat subtle changes to the upper critical temperature will be observed. This phenomenon is termed ‘heat-hardening’ and recent data suggests that a cross-protection to other noxious challenges might also occur. We have evaluated the time course of this heat-shock response by exposing groups of channel catfish fry to 32, 34, or 36°C for 1, 5, or 10 min and then determined upper critical temperature in these animals 24, 48, and 96 h later. Overall these data illustrate that increasing the intensity of pre-treatment (e.g. increased temperature) leads to a more pronounced ‘heat-hardening’ response.  We are using these data to develop experimental models to investigate the phenomena of cross-protection associated with ‘heat-hardening’ and examine the mechanisms of this observed plasticity in thermal tolerance.