Effects of temperature and dietary protein on gene expression ofHsp70andWap65and immunity of juvenile mirror carp (Cyprinus carpio)

Abstract

Juvenile mirror carp were fed diets containing 303.4, 321.7, 341.2, 361.0 and 379.1 g kg−1 proteins, respectively, and reared at different water temperatures (18, 23 and 28°C) for 60 days. Gene expression of heat shock protein gene (Hsp70) and the warm temperature acclimation-related 65 kDa protein gene (Wap65), immunity and antioxidant status in the carp were investigated. Results indicated that the contents of serum complement 3 (C3), complement 4 (C4) and immunoglobulin M (IgM), as well as activities of liver superoxide dismutase (SOD) and lysozyme (LSZ) were significantly enhanced with increasing dietary protein (P < 0.05), while content of malondiadehyde (MDA) decreased. Gene expression level of Wap65 in the liver significantly increased with dietary protein, while gene expression of Hsp70 decreased. The contents of C3, C4 and IgM, the activities of SOD and LSZ and gene expression level of Wap65 in the liver significantly increased with temperature. These results suggest that: Serum immune parameter, antioxidant enzymes and Hsp70 and Wap65 expression interact in fish to improve ability to adapt to the environment; and the optimal conditions for the immunity of carp are 348.1˜354.5 g kg−1 protein at 18°C, 352.3˜364.9 g kg−1 at 23°C and 360.2˜364.3 g kg−1 at 28°C, and the optimum temperature for carp is 23°C.