Δ6 fatty acid desaturase gene in estuarine tapertail anchovy (Coilia nasus): Structure characterization and mRNA expression under different dietary and fasting conditions

The enzyme δ6-fatty acid desaturase regulates the rate of highly unsaturated fatty acid (hufa) biosynthesis. we first obtained the cdna sequences and structures of fads6 in coilia nasus and investigated the mrna expression patterns in tissue,and in juveniles under different dietary regulation. the fads6 cdna was 2032 bp,specifying a protein of 445 amino acids. a high expression was observed in the brain and intestine,relatively high expression in muscle and liver,and a weak expression was exhibited in the heart,kidney and gill. the effects of three different diets (diet 1-soft pellet; diet 2-slow-sinking pellet; diet 3- daphnia) were studied on lipid metabolism enzyme activities and gene expression levels in different tissues of juveniles of c. nasus for 60 d. the differential expression of fads6 genes in liver,brain and intestine changed with different diets,respectively. we detected lipid metabolism enzyme-specific activities such as lipase enzyme,lipoprotein lipase enzyme and lipid peroxides in liver,and found that the lipase activity in liver of diet 2 group was significantly (p<0.05) higher than the other diets. the mechanism of hufas synthesis in c. nasus is described in the future. copyright 2016 zoological society of pakistan.