Integrative transcriptomic and lipidomic analysis of the effects of Eucommia ulmoides on growth performance and lipid metabolism in Larimichthys crocea.

INTRODUCTION: Larimichthys crocea is an economically important marine aquaculture species, and improving growth performance while maintaining lipid metabolic homeostasis is important for its sustainable production. This study investigated the effects of dietary Eucommia ulmoides supplementation on growth performance and lipid metabolism in L. crocea and explored the underlying molecular basis using integrated transcriptomic and lipidomic analyses.

METHODS: A 4-week feeding trial was conducted using a control diet and a diet supplemented with 0.3% E. ulmoides. Growth performance, plasma biochemical indices, hepatic lipid accumulation, transcriptomic profiles, and lipidomic profiles were evaluated. Integrated pathway analysis was further performed to identify metabolic pathways jointly represented in the transcriptomic and lipidomic datasets.

RESULTS: Dietary supplementation with 0.3% E. ulmoides significantly increased the specific growth rate (SGR) of L. crocea (P < 0.05) and reduced the feed conversion ratio (FCR; 1.38 in the E. ulmoides group versus 2.68 in the control group). Hepatic Oil Red O staining revealed reduced lipid staining in the E. ulmoides group, while plasma biochemical analyses showed decreased triglyceride levels and improved antioxidant status. Integrated transcriptomic and lipidomic analyses identified glycerolipid metabolism and glycerophospholipid metabolism as the principal pathways represented in both omics datasets. In glycerolipid metabolism, differentially expressed genes (DEGs) were mapped to reactions involving intermediate metabolites associated with neutral-lipid synthesis. In glycerophospholipid metabolism, DEGs were mapped to reactions involving phosphatidylglycerol (PG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), and their precursors. Notably, pathway-level co-mapping showed that these two metabolic pathways converge at phosphatidic acid (PA; 1,2-diacyl-sn-glycerol-3-phosphate), suggesting a potential metabolic connection between neutral-lipid storage and membrane lipid remodeling.

DISCUSSION: These findings indicate that dietary E. ulmoides supplementation can improve growth performance and modulate lipid metabolism in L. crocea. The coordinated changes in glycerolipid and glycerophospholipid metabolism, potentially linked through PA, provide a molecular basis for the observed reduction in hepatic lipid accumulation and suggest that E. ulmoides may promote lipid metabolic homeostasis in L. crocea.