P1.203 Wednesday, Jan. 4 Evaluation of Thermally Induced Cross-Protection in Channel Catfish TAYLOR, Gordon*; WILSON, Alichia; HAUKENES, Alf; Univ. of Arkansas at Pine Bluff; Univ. of Arkansas at Pine Bluff; Univ. of Arkansas at Pine Bluff email@example.com
Heat stress initiates a suite of cellular responses across a wide range of plant and animal phyla. These responses can lead to increased resistance to subsequent stressors (e.g. heat, salinity); this latter phenomenon is often referred to as cross-protection. We applied a heat stress treatment to groups of channel catfish fingerlings (32, 34, or 36°C for 1, 5, or 10 min). Upper critical temperatures (UCT) were determined for these animals 24, 48, and 96h after heat treatments. Fish exposed to 34 or 36°C had significantly greater UCT than non-treated controls and the increased UCT was observed for 96 h following heat hardening for animals receiving the 36°C treatments. To evaluate cross protection we exposed animals to 36°C for one minute and 24, 48, or 96 h later groups of animals were immersed in a 35 ppt NaCl solution. Mean time to death for heat treated and control animals were compared. Fish pre-treated with a thermal stressor had significantly higher mean time to death than controls at both 48 and 96h after heat treatment. In a similar experiment, fish were hardened and exposed to high pH (10.9) 24, 48 or 96h after heat treatment. At 96h post hardening, mean time to death during the pH challenge was significantly greater in heat treated animals than control fish. These results provide evidence of heat hardening and cross protection in channel catfish. The utility and mechanisms of this response continue to be investigated in order to determine if inducing the heat shock response before events like transport and stocking can ameliorate some of the negative manifestations of stress that are attributed to these events.