Abstract:This study investigated effects of exogenous Vitamin C (VC) on the membrane time, hatching ratio, survival rate, growth characteristics, digestive enzyme activities and Lipases enzyme activities of spotted halibut (Verasper variegatus) during early development using mature eggs by the method of artificial fertilization. The eggs were divided into five groups with five different VC concentration of 0, 20, 25, 30, and 35 mg/L, respectively. Samples were collected at mature eggs, fertilized eggs, mid-gastrula, crystal appear, mixed nutrition and exogenous nutrition stages. The results showed that 25 mg/L VC significantly improved the hatching ratio, survival rate and growth characteristics and shorten the membrane time, and that VC contributed to the deposition of protein in spotted halibut during early development, and significantly enhanced the activity of pepsin after exogenous nutrition stage (P<0.05). After mixed nutrition stage, VC significantly increased the activity of amylase (P<0.05). After endogenous nutrition stage, VC significantly induced the activity of lipase and trypsin (P<0.05). VC at 25 mg/L increased the activities of lipoprotein lipase and hepatic lipase enzyme during embryo development (P<0.05). The findings indicated that lipoprotein lipase and hepatic lipase genes in zygotes may play functions at gastrula stage when lipid hydrolytic enzymes express to release energy for embryonic development. The results demonstrate that lipase and trypsin priority digest carbohydrates in yolk of mature eggs from spotted halibut to provide energy for embryonic development right after fertilization. The study revealed that appropriate level of VC could improve lipid metabolism during embryo development of spotted halibut.
