Single nucleotide polymorphisms within the estrogen receptor beta gene are linked with reproductive indices in Japanese flounder, Paralichthys olivaceus

The objectives of this study were to characterize polymorphisms within the coding region of estrogen receptor β (ERβ) gene in a population of 57 female Japanese flounder (Paralichthys olivaceus) and to analyze the association of ERβ polymorphisms with reproductive indices by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP). Two single nucleotide polymorphisms (SNPs), SNP1 (c.577delC) and SNP2 [c.A891T (p.Gln114Leu)], were identified in the ERβ gene. A one-way ANOVA revealed that SNP1 was significantly associated with the gonadosomatic index (GSI) in female Japanese flounder (P < 0.05). And SNP2 was significantly associated with the serum 17β-estradiol (E2) level and GSI (P < 0.05). Individuals with genotype AB of SNP2 had significantly higher serum E2 level and GSI than those of genotype AA (P < 0.05). Moreover, the hepatosomatic index (HSI), a marker for genetic effects, was significantly higher for diplotype D2 compared with the other three diplotypes (P < 0.05). These results obtained in this study suggested that SNP2 could influence reproductive endocrinology of female Japanese flounder and be useful as a potential candidate genetic marker for the selection of reproductive indices in female Japanese flounder.