Metabolic differentiation of diploid and triploid European sea bass juveniles

Abstract

The effects of triploidy were studied on indices of growth and metabolism in juvenile European sea bass. Ploidy affected flesh quality of Dicentrachus labrax, as protein and water contents were significantly higher in triploid than in diploid fish and triploid fish exhibited significantly lower lipid content. Compared to 2n fish, triploid fish exhibited 53.4% and 28.6% more DNA and RNA, respectively, 17.2% higher RNA/DNA ratio and 28.7% more protein/DNA ratio. The activities of the aerobic metabolism enzyme CCO and the glycolytic LDH of the muscle tissue were significantly higher in the triploid fish. Nevertheless, the ratio of these two enzymes was lower in the triploids, indicating metabolic difference in the potential for aerobic metabolism. The increased activity of LDH may reflect a potential shift towards anaerobic metabolism required under demanding conditions, for example, during burst swimming, confirming the effects of ploidy on the aerobic swimming capacity of fish. The increased CCO activity of triploids observed in the present work indicates an effect of ploidy on the capacity for aerobic metabolism of triploid fish.