Transcriptome and lipidomics profiling of F2 generation female Chinese sturgeon (Acipenser sinensis) in response to different arachidonic acid diets

Our previous study indicated that dietary arachidonic acid (ARA) inclusion levels higher than 1% in the diet play key roles in ARA deposition, steroid and vitellogenin (Vtg) synthesis in F₂ generation female Chinese sturgeon, but the regulatory mechanism remains to be elucidated. As follow-up to our previous study (Aquaculture Reports, 21, 100818), the study further aimed to investigate the possible mechanisms of the effects of dietary ARA promoted steroid hormone synthesis in the ovary by transcriptomics and in the serum by lipidomics. RNA-Seq and lipidomics technology were employed to profile the ovary transcriptome and serum lipidomics after feeding four ARA supplemented diets (named CT, LT, MT and HT), and the differentially expressed genes (DEGs) and key differential metabolites were identified. A total of 1018 DEGs, 853 DEGs, 2680 DEGs, 303 DEGs, 1185 DEGs and 409 DEGs were identified in the LT versus CT, MT versus CT, HT versus CT, MT versus LT, HT versus LT and HT versus MT comparisions, respectively. Gene ontology showed that the DEGS between the ARA-supplemented diet group and the unsupplemented diet group were enriched in regulation of cellular process, development process and reproduction. Pathways concerning steroid hormone biosynthesis and cholesterol biosynthesis in lipid metabolism and ovarian steroidogenesis as well as the nuclear-initiated estrogen signaling pathway in endocrine system were enriched. Furthermore, weighted correlation network analysis (WGCNA) identified six hub genes that regulate gonad development and cholesterol synthesis, namely, mitogen-activated protein kinase (MAPK14), cyclin-dependent kinase 2 (CDK2), heat shock protein 8 (HSPA8), two forkhead boxes (FOXP3 and FOXJ3) and cytochrome P₄₅₀ sterol 14α-demethylase (CYP51A1). Collectively, the molecular mechanism by which ARA regulates the synthesis of steroids, may be related to enhanced cholesterol ester metabolism and facilitation of steroidogenesis gene transcription, which ultimately benefits ovary development in F₂ generation Chinese sturgeon.