Identification of single nucleotide polymorphism cytochrome P450-c19a and its relation to reproductive traits in Japanese flounder (Paralichthys olivaceus)

CYP19 is considered as an important factor affecting reproductive endocrinology in many fishes, and plays an important role in ovarian development, reproductive function and sexual differentiation. In this study, three single nucleotide polymorphisms (SNPs) within CDS of the CYP19a gene were tested and the associations between their genotypes and four reproductive traits were analyzed in 65 Japanese flounder individuals with Polymerase chain reaction and Single-stranded conformational polymorphism (PCR–SSCP). Results indicated that a SNP in the exon7 of CYP19a gene, SNP2, was significantly associated with 17β-estradiol (E2) (P < 0.05) and gonadosomatic index (GSI) (P < 0.05). Individuals with genotype AB of SNP2 had significantly higher serum E2 levels (P < 0.05) and GSI (P < 0.05) than those of genotype AA or BB. In addition, there was significant association between one diplotype based on three SNPs and reproductive trait. The genetic effects for both serum E2 of diplotype D9 and GSI of diplotype D1 were respectively much higher than those of other diplotypes (P < 0.05). The evidence of the associations between genetic variants with serum E2 and GSI may help explain effects of CYP19a gene in reproductive endocrinology of Japanese flounder.