Objectives The effects of growth trait selection on the genes expression and metabolites levels in the eggs of landlocked Oncorhynchus masou were investigated by transcriptomics and metabolomics.
Methods Eggs were collected from 15 non-selected and 15 fifth-generation (F5) selected landlocked O. masou. Differences in gene expression and metabolites levels between the eggs of the two species were analyzed by combining transcriptomics and metabolomics.
Results The results of the transcriptome analysis revealed a total of 10880 differentially expressed genes (DEGs), primarily enriched in ribosomes, oxidative phosphorylation, lysosomes, and FoxO signaling pathways. Among these, the selected line of landlocked O. masou exhibited upregulated expression of gonadotropin (Gn), gonadotropin-releasing hormone (GnRH), and follicle-stimulating hormone (FSH) genes associated with oogenesis promotion, while downregulated expression of gonadotropin-inhibiting hormone (GnIH) genes related to oogenesis inhibition. The results of the metabolomics analysis revealed 583 differentially expressed metabolites (DEMs). Among these, the levels of vitellin (Vn), alkaline phosphatase (AKP), malate dehydrogenase (MDH), α-tocopherol, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) were higher in the selected group compared to the non-selected group. Conversely, the levels of vitamin B2, spermine, and adenosine were lower in the selected group compared to the non-selected group. The combined analysis revealed that phospholipid, lysine, glucose and fatty acid metabolic signaling pathways participate in ovarian development by enhancing lipid and fatty acid matabolism.
Conclusions Continuous selection had significant effects on gene expression and metabolite levels of landlocked O. masou eggs, and phospholipid, lysine, glucose and fatty acid metabolic signaling pathways played important roles in the development of ovarian and eggs.
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