Cloning and nutritional regulation of polyunsaturated fatty acid desaturase and elongase of a marine teleost, the nibe croaker Nibea mitsukurii

Abstract

We identified fatty acid desaturase (fads)-like and elongase (elovl)-like genes from nibe croaker to better understand the molecular basis of n-3 highly unsaturated fatty acid metabolism in marine fish. Phylogenetic analysis revealed that the fads-like and elovl-like genes were classified into the fads6 and elovl5 groups, respectively. We investigated the effects of various levels of docosahexaenoic acid (DHA)-enriched live feed, Artemia nauplii, on larval growth, survival, and fads-like and elovl-like gene expression. After a 15-day feed trial, total length, body weight, and survival were all significantly improved by the supplementation of Artemia with DHA. This result indicates that nibe croaker cannot endogenously produce enough DHA. Furthermore, the fads-like gene transcripts in larvae fed on oleic acid-enriched Artemia were significantly higher than those in larvae on 100% DHA-enriched Artemia. In contrast, no significant differences were observed in the transcript levels of the elovl-like gene. These data indicate that the fads6-like gene was controlled by negative feedback from the quantity of DHA stored in the larval body. These results have implications for the functionality of the fads-like gene in nibe croaker.