Effects of different dietary lipid sources on growth performance, hepatic lipid deposition and transcriptome response in spotted sea bass (Lateolabrax maculatus)

A 150-day feeding experiment was conducted to investigate the effects of dietary lipid sources on growth per-formance, hepatic lipid deposition, and transcriptome response in spotted sea bass (Lateolabrax maculatus). Four experimental diets were formulated with supplementation of four different lipid sources including fish oil (FO, the control), tea seed oil (TO), perilla oil (PO), and soybean oil (SO). There was no significant difference in growth parameters or body proximate composition among dietary treatments. Replacement of FO with vegetable oils induced significant increases in hepatic lipid droplets, suggesting the presence of lipid abnormal deposition. Fish fed the diet with FO showed significantly lower content of C18:1n-9 and higher contents of C20:5n-3 and C22:6n-3 in the liver compared with the other groups. Furthermore, a transcriptome analysis of liver tissue was carried out to further characterize the molecular mechanism of lipid deposition. A total of 61, 32, and 103 differentially expressed genes (DEGs) were identified in FO vs. TO, FO vs. PO, and FO vs. SO groups, respectively. These DEGs were divided into two sets (fatty acid metabolism and steroid synthesis). The transcriptomic results were further validated by quantitative RT-PCR on lipid metabolism-related key genes in the liver. The increase of fatty acids and steroids might induce the generation of triglycerides responsible for lipid deposition. The study provided a comprehensive view of the molecular mechanism of lipid metabolism in spotted sea bass and served as an information base for the formulation of feeds with vegetable oils in the future.