Post-feeding molecular responses of cobia (Rachycentron canadum): RNA-sequencing as a tool to evaluate postprandial effects in hepatic lipid metabolism

Abstract

Abstract We used transcriptome sequencing to investigate the hepatic postprandial responses of Rachycentron canadum (cobia), an important commercial fish species. In total, 150 cobia juveniles (50 per tank, triplicate) were fed ad libitum with a commercial diet for 7 days, fasted for 24 h and fed for 10 min. Liver samples were sampled 10 min before and 30 min, 1, 2, 4, 8, 12, and 24 h after the feed event. Posteriorly, it was evaluated liver fatty acid profile, transcriptome sequencing, and differential gene expression focusing on fatty acid synthesis and oxidation pathways. In general, liver fatty acid profile reflected the diet composition. Docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) levels increased at 8 to 12 h and decreased at 24 h after the feed event. It was observed a high number of differentially expressed genes (DEGs) comparing fish fasted by 8 h with those fasted by 30 min and 24 h, while a reduced number of DEGs was observed comparing individuals fasted by 30 min compared with those fasted by 24 h. Similarly, the main differences in the expression of genes related to the fatty acid biosynthesis and oxidation pathways were noticed in individuals fasted by 8 h compared with those fasted by 30 min and 24 h. The results suggested that the adequate time to sample the individuals ranged between 8 and 12 h after meal, since apparently, after 24 h, differential gene expression was not necessarily influenced by feed intake.