Molecular cloning and nutritional regulation of putative ∆6 desaturase mRNA from striped catfish (Pangasianodon hypophthalmus)

The fatty acid composition of fish depends on both dietary fatty acid input and endogenous HUFA biosynthesis capacity. Fatty acyl desaturases (fads) introduce double bonds in selected positions of the acyl chains. Particularly, Δ6 FADS are the first enzymes involved in the biosynthesis of long-chain HUFA from the C18 n-3 and n-6 precursors, which is a rate limiting step. The extent to which fish can desaturate/elongate C18 FAs to HUFAs varies with species. Hence it is important to study the relationships between LC-PUFA biosynthesis pathways and the habitat and feeding habit of fish species, which will provide the basis for understanding the regulatory mechanisms controlling LC-PUFA biosynthesis pathways. The present study reports the full-length cDNA cloning, tissue distribution and nutritional regulation of Δ6 fads-like gene from freshwater catfish, P. hypophthalmus. This is the first report on cloning and expression analysis of Δ6 fads-like gene from any freshwater catfish.