Comparative lipidomics profiling of the sea urchin, Strongylocentrotus intermedius

Strongylocentrotus intermedius is an edible sea urchin and well-known for its nutritional value, such as a high content of polyunsaturated fatty acids (PUFAs). We carried out an untargeted lipidomics via high-resolution ultra-high-performance liquid chromatography - mass spectrometry (UPLC-MS) to highlight the features of the lipids profile of sea urchin gonad, which allowed for a more detailed interpretation of the accumulation of PUFAs with different abundances among sea urchins. For the first time, lipidomics profiling of lipid abundances in S. intermedius was demonstrated. We detected 11 PUFAs in sea urchin gonads, which represented >54.13% of the total fatty acid content. A total of 1552 lipid molecular species belonging to 36 lipid classes were identified. Lipidomics profiles data were analyzed using orthogonal partial least squares discriminant analysis (OPLS-DA) model and distinguished the PUFA abundances in both sexes of sea urchins. The significant differences in lipid molecules were highlighted and the major lipid classes identified were phosphatidylcholine (PC [19 species]) among females and triglycerides (TG [11 species]) among males. PC (42: 11) may be used as a potential marker for distinguishing high levels of PUFAs in sea urchin individuals, which as the result of the high level of PC (42:11). These data enrich the lipid profile library of aquatic products and provide a more reliable and refined biomarkers for the further research on fatty acid synthesis and metabolism in aquatic animals.