Molecular Characterization and Nutritional Regulation of Two Fatty Acid Elongase (elovl8) Genes in Chinese Perch...

Proteins for elongation of very long-chain fatty acids (ELOVLs) are critical for the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs), and they are one group of the rate-limiting enzymes responsible for the initial condensation reaction within the fatty acid elongation. Elovl8 is a newly identified member of the ELOVL protein family, and its evolutionary and functional characterizations are still rarely reported. Here, we identified two elovl8 paralogues (named Scelovl8 and Scelovl8b) from Chinese perch (Siniperca chuatsi), and then their molecular and evolutionary characteristics, as well as potential roles involved in LC-PUFA biosynthesis, were examined. The ORFs of both Scelovl8a and Scelovl8b genes were 810 bp and 789 bp in length, encoding proteins of 270 and 263 amino acids, respectively. Multiple protein sequence comparisons indicated that elovl8 genes were highly conserved in teleosts, showing similar structural function domains. Meanwhile, phylogenetic analysis showed that the elovl8 gene family was clustered into two subclades of elovl8a and elovl8b, and Scelovl8a and Scelovl8b shared close relationships with banded archerfish elovl8a and striped bass elovl8b, respectively. Genetic synteny and gene structure analyses further confirmed that elovl8b is more conserved in comparison to elovl8a in teleosts. In addition, Scelovl8a was found to be highly expressed in the liver, while Scelovl8b was most abundant in the gills. Long-term food deprivation and refeeding are verified to regulate the transcription of Scelovl8a and Scelovl8b, and intraperitoneal injection of fish oil (FO) and vegetable oil (VO) significantly modified their gene expression as well. In summary, our results in this study indicate that elovl8 genes were conservatively unique to teleosts, and both elovl8 genes might be involved in the endogenous biosynthesis of LC-PUFAs in Chinese perch. These findings not only expand our knowledge on the evolutionary and functional characteristics of both elovl8 genes but also lay a solid basis for investigating regulatory mechanisms of LC-PUFA biosynthesis in various teleosts.