The effects of temperature on the cytochrome P-450 system of thermally acclimated bluegill

The effects of temperature acclimation at 10, 20 and 30 degrees C on the concentration and activity of the mixed function oxidase system in bluegill are as follows. Liver weight/body weight varied inversely with temperature. Significant (P less than 0.05) differences in concentration of cytochrome P-450 of hepatic microsomes were seen and varied inversely with temperature. Benzo(a)pyrene hydroxylase activity tested in vitro at incubation temperatures of 10, 20 and 30 degrees C showed significant differences in Km, but no differences in Vmax. SDS polyacrylamide gel electrophoresis revealed some quantitative differences in cytochrome P-450 isozymes between groups.