Characterization of two lipid metabolism-associated genes and their expression profiles under different feeding conditions in Acipenser dabryanus

Acipenser dabryanus is an endemic species restricted to the upper reaches of the Yangtze River and is listed as a national first-class protected animal in China. In the present study, two lipid metabolism-associated genes, namely, lipoprotein lipase (LPL) and apolipoprotein E (apoE), were identified from the full-length transcriptome analysis of A. dabryanus. The full-length genes encoded polypeptides with typical conserved motifs and functional sites shared with their homologues in other fish. Gene expression profile analysis showed that the LPL and apoE genes were constitutively expressed in A. dabryanus. The highest expression level of LPL was found in the muscle, while apoE was predominantly expressed in the liver. In the fasting and refeeding experiment, one hundred twenty fish were randomly assigned to four groups (fasting 0, 3, 7 or 14 d and then refed for 14 d). Fasting and refeeding significantly regulated the expression level of LPL with various expression patterns in different tissues, whereas starvation showed little effect on apoE expression. In addition, the expression levels of LPL and apoE were significantly affected by feeding frequency. The fish were bred for eight weeks at six different feeding frequencies groups (once a day, two times a day, three times a day, four times a day, five times a day and six times a day). Both LPL and apoE expression levels were significantly upregulated in the liver in the highest feeding frequency group. Our study suggests potential roles for LPL and apoE in lipid metabolism in A. dabryanus and will be useful for further study of nutrition regulation in fish.