Hepatopancreas transcriptomic and lipidomic analyses reveal the molecular responses of mud crab (Scylla paramamosain) to dietary ratio of docosahexaenoic acid to eicosapentaenoic acid

To investigate the metabolic response of mud crab Scylla paramamosain to dietary ratio of docosahexaenoic acid (DHA) to eicosapentaenoic acid (EPA), transcriptomic and lipidomic analyses were conducted on the hepato-pancreas of crabs (initial weight 20.92 & PLUSMN; 0.56 g) fed for 8-week with diets having suboptimum (0.6) and optimal (2.3) DHA/EPA ratios. The analyses identified 358 up-regulated and 432 down-regulated differentially expressed genes, and 48 up-regulated and 30 down-regulated differential lipid molecules with 53% phosphatidylcholine, 14% phosphatidylethanolamine and 13% phosphatidylinositol. GO analysis, KEGG pathway enrichment and network of interaction analysis identified pathways of glycerophospholipid metabolism, PPAR signaling, oxidative phosphorylation, ribosome and thermogenesis as being significantly affected by dietary DHA/EPA ratio. Specifically, dietary DHA/EPA ratio regulated the expression of genes in lipid metabolism and PPAR signaling pathways such as fas, fabp-1/3, fatp, cptI and aco. Compared to the suboptimum ratio, the optimum dietary DHA/EPA ratio down regulated the gene experssion of phospholipase D1/2 and glycerol-3-phosphate O-acyltransferase in glycerophospholipid metabolism pathway, akt and s6 in mTOR pathway, ask1 in thermo-genesis and non-alcoholic fatty liver disease pathway, and up regulated the pepck experssion in PPAR signaling pathway. Thus, dietary DHA/EPA ratio influence the lipid, protien and carbohydrate metabolism, immune response, and even the cell member structure. The findings improved our understanding of the impacts and molecular mechanisms of a nutritional challenge, in this case the dietary DHA/EPA ratio, increased basic knowledge of multi-omics analysis of in a commercially important crustacian species, the mud crab S. paramamosain, and provided the framework for further in-depth functional studies to promote sustainable aquaculture.