ISOZYME PATTERNS IN TISSUES OF TEMPERATURE-ACCLIMATED FISH

Abstract

ABSTRACT. Lactate dehydrogenase and malate dehydrogenase isozyme patterns from goldfish ( Carassius auratus L.) tissues were examined by starch gel electrophoresis. Electrophoretic analyses reveal no detectable qualitative or quantitative alterations in the isozyme patterns due to the effects of temperature acclimation at 5°, 15°, and 25°C. The only variations of LDH isozyme patterns observed were those attributable to genetic polymorphism and to the different isozyme patterns of white and red skeletal muscle fibers. Specific activity of LDH was similar for all acclimation temperatures. Various glycolytic and oxidative isozymes from green sunfish ( Lepomis cyanellus ) tissues were examined by starch gel electrophoresis and spectrophotometric activity analysis. No qualitative alterations were noted in the isozyme patterns due to the effects of temperature acclimation at 5° and 25°C although quantitative alterations were observed. Warm-acclimated sunfish display an increase in glycolytic enzymes (LDH, aldolase, phosphoglucomutase, G-3-PDH) and a decrease in an oxidative enzyme (MDH). Cold-acclimated sunfish display increased oxidative enzyme activity and decreased glycolytic enzyme activity. We conclude that qualitative isozyme alterations of these enzyme systems occur as a direct result of temperature acclimation only in trout, while other groups of fish show either quantitative alterations or no changes in isozyme patterns.