Cloning of hepatic lipase and the effects of dietary nutrition on hepatic lipase expression in genetically improved farmed tilapia (Oreochromis niloticus)

Hepatic lipase is an important gene in lipid metabolism, which is crucial in the growth of fish. In this study, the cDNA sequence of genetically improved farmed tilapia (GIFT) HL gene was cloned by aimed rapid amplification of cDNA ends (RACE) method. Then, the characteristics of HL were analyzed with bioinformatics methods, and the expression of HL was assessed by the quantitative real-time PCR. To study the regulation of HL expression, GIFT were fed with diets containing different contents of lipid (40, 80, and 120 g kg(-1)) and choline (500, 750, and 1000 mg kg(-1)) and fed with different frequencies (2 or 3 times/day) and amounts (20, 40, 60, 80, and g kg(-1) of body weight). Our results revealed that the GIFT HL gene has a full length of 1872 bp, encoding 493 amino acids. Consistent with the study in other species, GIFT HL was specially expressed in the liver. The HL gene of GIFT shared identity of 60.9-96.6% with other species. The expression of HL in 120 g kg(-1) dietary lipid and 1000 mg kg(-1) dietary choline group was the highest in all groups (P < 0.01). The expression of HL was increased gradually with 3 times/day frequency. All these results revealed the cDNA sequence of GIFT HL, and the expression of HL was affected by dietary choline and lipid levels, feeding frequency, and amount. This would guide the aquaculture of GIFT in the future.