Lipidomic profiling reveals molecular modification of lipids in hepatopancreas of juvenile mud crab (Scylla paramamosain) fed with different dietary DHA/EPA ratios.

• The lipid molecules most affected by dietary DHA/EPA ratio were GPs. • The sn-2 position of PE was the predominant binding site for 18:2n-6. • Dietary DHA and EPA competed with ARA and 18:2n-6 for esterification sites. • Optimal dietary DHA/EPA ratio increased LC-PUFA at sn-2 in PC molecules. • Optimal dietary DHA/EPA ratio improved the nutritive value of mud crab. Untargeted lipidomic analysis was conducted to explore how different dietary docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) ratio and, specifically, how an optimal ratio (2.3) compared to a suboptimum ratio (0.6) impacted lipid molecular species and the positional distribution of fatty acids in hepatopancreas of mud crab. The results indicated that major category of lipid affected by dietary DHA/EPA ratio was glycerophospholipids (GPs). The optimum dietary DHA/EPA ratio increased the contents of DHA bound to the sn-2 and sn-3 positions of phosphatidylcholine (PC) and triacylglycerol, EPA bound to the sn-2 position of phosphatidylcholine and 18:2n-6 bound to the sn-2 position of phosphatidylethanolamine (PE). Increased dietary DHA/EPA ratio also led to competition between arachidonic acid (ARA) and 18:2n-6 bound to esterified sites. Appropriate dietary DHA/EPA ratio can not only improve the growth performance and nutritional quality of mud crab, but also provide higher quality products for human consumers. [ABSTRACT FROM AUTHOR]