Nutritional regulation of genes responsible for long-chain (C20-24) and very long-chain (>C24) polyunsaturated fatty acid biosynthesis in post-larvae of gilthead seabream (Sparus aurata) and Senegalese sole (Solea senegalensis)

Abstract

The fatty acyl elongases Elovl4 are pivotal components in the biosynthesis of very long-chain polyunsaturated fatty acids (VLC-PUFA) from long-chain polyunsaturated fatty acids (LC-PUFA). Thus, nutritional regulation of Elovl4, as well as other elongase and desaturase genes involved in LC-PUFA biosynthesis (e.g., Elovl5, Fads2) has been proposed as a strategy to enhance endogenous production of LC-PUFA and VLC-PUFA under intensive farming conditions. This study aimed at investigating the nutritional regulation of genes involved in the biosynthesis of VLC-PUFA (elovl4 isoforms a and b) and LC-PUFA (fads2, elovl5) in Sparus aurata and Solea senegalensis post-larvae fed three inert micro-diets with graded concentrations of dietary LC-PUFA by using different combinations of fish oil and soya oil. The effect of dietary LC-PUFA on survival, growth and fatty acid composition was also examined. The results denoted that, while no effects were observed in survival, fish fed the diet with the highest LC-PUFA content during 30 d showed a higher total length and wet weight. Gene expression results showed that fads2, elovl5, elovl4a and elovl4b can be regulated by dietary LC-PUFA content. Remarkably, our results denoted a differential elovl4 nutritional regulation associated to each species. The head is the body part studied with the highest elovl4 transcripts in both fish species.