The Promoter SNPs Were Associated with Both the Contents of Poly-Unsaturated Fatty Acids (PUFAs) and the Expressions of PUFA-Related Genes in Common Carp

Abstract

The allo-tetraploid common carp encodes two duplicated fads2 genes (fads2a and fads2b) and two duplicated elovl5 genes (elovl5a and elovl5b). The coding SNPs (cSNPs) of these genes were reported to be significantly associated with the PUFA contents. Whether the promoter SNPs (pSNPs) were associated with the PUFA contents has not been reported yet. In this study, after sequencing the promoters of these four genes, we identified six pSNPs associated with the contents of PUFAs in common carp, including one elovl5a pSNP, one elovl5b pSNP, and four fads2b pSNPs. The pSNPs were predicted in the locations of transcriptional factor binding sites. Together with previously identified cSNPs in fads2b and elovl5b, the pSNPs and cSNPs of these two genes had the joint effects on the PUFA contents with higher explained percentage of phenotypic variation of the PUFA contents than single gene. The expression levels of both fads2a and fads2b were significantly positively correlated with the contents of six PUFAs. The fads2b pSNPs corresponding to higher fads2b expression levels were associated with higher PUFA contents. The pSNPs and cSNPs will be useful for the future selection breeding of common carp with higher PUFA contents.

Contribution of elovl5a to Docosahexaenoic Acid (DHA) Synthesis at the Transcriptional Regulation Level in Common Carp, Cyprinus carpio

“…The biosynthesis of PUFAs in fish is a process in which LA and ALA are used as substrates to synthesize PUFA through continuous desaturation and elongation reactions. This synthesis pathway is mainly catalyzed by fatty acid desaturase (Fads) that catalyzes the desaturation reaction and elongase of very-long-chain fatty acids (Elovl) that catalyze the carbon chain extension reaction [7,8]. The elovl gene family, which encodes the synthesis of C18 or longer chain fatty acids [9], is a rate-limiting enzyme in these reaction steps [10], playing a crucial role in fatty acid synthesis [11].…”