屋外飼育コイの糖代謝酵素活性および脂質含量の季節変化

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Seasonal changes of carbohydrate-metabolizing enzyme activity and body composition were investigated in common carp Cyprinus carpio fed to satiation with a commercial diet in an outdoor aquarium for more than one year. The hepatopancreatic glucosephosphate isomerase activity and serum triglyceride concentration were high in spring and summer and low in winter, reflecting changes in their feeding rates, and the reverse situation was found for GOT and GPT activities as welll as serum free amino acid and free fatty acid concentrations. The activities of glucose-6-phosphate and phosphogluconate dehydrogenases in pentosephosphate cycle increased from spring to autumn, and came up to their highest value in this season, then decreased markedly in winter. The seasonal change of these dehydrogenase activities coincided with that of the hepatopancreas and body fat content, suggesting that the decrease in environmental temperature in autumn causes an activation of the pentosephosphate cycle dehydrogenases to accelerate fatty acid synthesis in spite of a lower feeding rate, resulting in marked accumulation of body fat in early winter in the poikilothermic animal. It is also assumed that environmental temperature can cause various and reasonable changes in levels of carbohydrate-metabolizing enzymes and body components through chanes in their feeding rate.
日本水産學會の論文