Comparative metabolomics analysis based on LC-MS method reveals regulatory difference in lipid metabolism and fatty acids metabolism between diploid and triploid rainbow trout (Oncorhynchus mykiss)

Diploid rainbow trout gonadal development occurs at the expense of stored energy and nutrients, lipid mobilization supplies energy required for this process. However, triploid rainbow trout gonads are not developed, the lipid and fatty acid metabolism might be different. However, which metabolic pathways and key metabolites regulate fatty acid metabolism have not been clarified. To identify the metabolism difference between diploid and triploid rainbow trout, we use the LC-MS technology based metabolomics to detect the metabolites in positive and negative ion mode. As far as it was evaluated, there are 174 metabolites with statistically significant differences, including 13 lipids and lipid-like molecules. Among the different metabolites, linoleic acid (LA), oleic acid (OA) and arachidonic acid (ARA) were related to the biosynthesis of unsaturated fatty acids, LA and OA were related to linoleic acid metabolism. The two metabolic pathways related to Polyunsaturated fatty acid (PUFA) metabolism might be associated with the differences in PUFA contents in diploid and triploid rainbow trout serum. Gene expression results validated that and pointed that the desaturation process maybe more crucial process in the differential metabolic pathways between diploid and triploid rainbow trout. The study provide a theoretical explanation for PUFA metabolism differences between diploid and triploid rainbow trout, identify the crucial metabolites as biomarkers to differentiate the metabolic mechanisms of PUFA metabolism in rainbow trout.