Comparison of antioxidant capacity and immune response between low salinity tolerant hybrid and normal variety of Pacific white shrimp (Litopenaeus vannamei)

The Pacific white shrimp (Litopenaeus vannamei) is an economically important aquaculture species worldwide. Antioxidant immune performance is an important indicator of healthy growth and physiology of aquatic organisms. In this study, we compared the antioxidant capacity and immune response between a low salt tolerant hybrid and a normal variety of shrimp (control) cultured at different salinities (1‰, 5‰, and 15‰). At 1‰ salinity, the apoptotic cell numbers, apoptosis rate, and reactive oxygen content of the hybrid group were significantly lower than those of the control group. The hybrid group also had stronger antioxidant enzyme activities (glutathione peroxidase, glutathione transferase, superoxide dismutase, catalase) and higher gene expression levels. In addition, the hybrid group cultured at low salinity (1‰ and 5‰) had significantly higher total hemocyte count, phagocytic rate, and respiratory burst than the control group. Similarly, the hybrid group had higher immune-related enzyme (acid phosphatase, alkaline phosphatase, lysozyme, phenol oxidase) activities and gene expression levels than the control group at low salinity. These results show that the hybrid population had better antioxidant and immune capacity than the normal variety when cultured under low salinity conditions, and they lay the foundation for selection and breeding of low-salt tolerant, high-quality Pacific white shrimp.