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

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 <i>elovl8</i> paralogues (named Sc<i>elovl8</i> and Sc<i>elovl8b</i>) from Chinese perch (<i>Siniperca chuatsi</i>), and then their molecular and evolutionary characteristics, as well as potential roles involved in LC-PUFA biosynthesis, were examined. The ORFs of both Sc<i>elovl8a</i> and Sc<i>elovl8b</i> genes were 810 bp and 789 bp in length, encoding proteins of 270 and 263 amino acids, respectively. Multiple protein sequence comparisons indicated that <i>elovl8</i> genes were highly conserved in teleosts, showing similar structural function domains. Meanwhile, phylogenetic analysis showed that the <i>elovl8</i> gene family was clustered into two subclades of <i>elovl8a</i> and <i>elovl8b</i>, and Sc<i>elovl8a</i> and Sce<i>lovl8b</i> shared close relationships with banded archerfish <i>elovl8a</i> and striped bass <i>elovl8b</i>, respectively. Genetic synteny and gene structure analyses further confirmed that <i>elovl8b</i> is more conserved in comparison to <i>elovl8a</i> in teleosts. In addition, Sc<i>elovl8a</i> was found to be highly expressed in the liver, while Sc<i>elovl8b</i> was most abundant in the gills. Long-term food deprivation and refeeding are verified to regulate the transcription of Sc<i>elovl8a</i> and Sc<i>elovl8b</i>, 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 <i>elovl8</i> genes were conservatively unique to teleosts, and both <i>elovl8</i> 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 <i>elovl8</i> genes but also lay a solid basis for investigating regulatory mechanisms of LC-PUFA biosynthesis in various teleosts.