Comparative transcriptome analysis provides new insights into the protective effect of astaxanthin on the liver of leopard coral grouper (Plectropomus leopardus)

Astaxanthin has been widely used as feed supplements in aquaculture, and the effects of which on the growth, immunity, and antioxidant system of aquaculture animals have been demonstrated by phenotype measurement and enzyme activity analysis. However, the molecular response to dietary astaxanthin of aquaculture animals has been rarely described. In this study, the comparative experiment was conducted employing coral grouper (Plectropomus leopardus) juveniles, which were fed with astaxanthin (AX group) or without astaxanthin (control group). The histological and antioxidant enzyme activities analysis of the livers showed dietary astaxanthin could reduce lipid accumulation and oxidative stress. By comparative transcriptome analysis of the livers, a total of 1992 and 981 differentially expressed genes (DEGs) were identified between the AX groups and the control groups at the 40- and 60-day after feeding trial, respectively. Functional analysis of DEGs showed that multiple enriched terms were related to oxidative stress, immune response, fat metabolism, cholesterol metabolism, and steroid biosynthesis. Furthermore, the functions of specific DEGs in oxidative stress and immune response were validated in primary cultured hepatocytes. Finally, weighted gene co-expression network analysis (WGCNA) was performed to construct gene co-expression networks, and identified key factors which may play vital roles in regulating the molecular response to astaxanthin feeding in livers of P. leopardus. Taken together, our findings facilitate the understanding of the molecular basis underlying the protective effect of dietary astaxanthin in P. leopardus, which provides valuable insights into the nutritional strategies of the aquaculture industry.