Temperature Acclimation of Enzyme Activities and Protein Synthesis in Channel Catfish (Ictalurus Punctatus). In Vivo and In Vitro Studies

Abstract

157 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.Hepatocytes from 15(DEGREES)C acclimated catfish isolated by collagenase perfusion were maintained for 3-4 weeks in primary culture at 7, 15, and 25(DEGREES)C on biomatrix prepared from liver structural proteins. Specific activities of enzymes of cultured hepatocytes showed acclimatory compensation for the following: cytochrome(DEGREES)C oxidase, citrate synthase, NADH-cytochrome(DEGREES)C reductase, and glucose-6-phosphate dehydrogenase. Lactate dehydrogenase showed no compensation. 6-phosphogluconate dehydrogenase showed partial inverse compensation. Hence, cultured hepatocytes show temperature acclimation of enzymes in patterns similar to those measured in vivo. Protein synthesis measured at 15(DEGREES)C by hepatocytes from catfish acclimated to different temperatures occurred in the series: 7 > 15 > 25(DEGREES)C acclimation. Protein synthesis measured at 15(DEGREES)C by cultured hepatocytes occurred in the series: 15 > 7 > 25(DEGREES)C. Protein degradation measured at temperatures of culture occurred in the series: 25 > 15 > 7(DEGREES)C. Changes in concentration of enzymes during acclimation may occur by direct temperature effects on rates of synthesis and degradation, and differences in temperature effects on protein synthesis in vitro and in vivo may result from absence of some critical substance in culture.In fluorographs of two-dimensional gel electrophoresis many polypeptides increased or decreased synthesis rates during low temperature acclimation; others did not change.The effect of temperature acclimation on heat-shock protein (hsp) synthesis was examined in hepatocytes isolated from catfish acclimated to 7 and 25(DEGREES)C. In 7(DEGREES)C acclimated fish hsp was maximal at 25-35(DEGREES)C, hsp of 25(DEGREES) at 35(DEGREES)C. Hsp is synthesized at lower temperatures by cold acclimated than by warm acclimated fish.Temperature acclimation of metabolic enzymes can occur in isolated cells in patterns similar to those in vivo. Temperature acclimation of protein synthesis in cultured cells follows a pattern different from that in intact fish. Temperature acclimation of protein synthesis is selective for specific proteins of mitochondria. Synthesis of heat-shock proteins can be altered by temperature acclimation.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD