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Cytochrome P450 aromatase (P450arom) is an enzyme responsible for the conversion of androgen into oestrogen. To study the role of ovarian aromatase (Cyp19a1a) in sex differentiation, the novel c DNA clone encoding ovarian aromatase (Cyp19a1a) was identified from the ovary of the black rockfish ( Sebastes schlegeli). The cloned c DNA is 1868 bp in length with 79 bp 5′U TR, 209 bp 3′UTR [excluding poly (A)] and contains 1550 bp ORF, encoding a protein of 516 amino acids. Alignment and phylogenetic analysis showed that the black rockfish ovarian aromatase (Cyp19a1a) shared 61-89% sequence identity with those of other seven fish species. The cyp19a1a transcript was found more highly abundant in ovary, but not detected in the testis, brain, liver, spleen, kidney, muscle, skin, heart, head kidney, gill, intestine and eyes by semi-quantitative reverse transcription ( RT)- PCR. The cyp19a1a gene is not equivalent in tissue-specific expression in the female and male, showed the possibility of distinct promoters and regulatory mechanisms. The expression level of cyp19a1a in ovary declined with the ovary development, but was higher than that in testis in all phases. These results indicated that cyp19a1a might be involved in gonadal development in S. schlegeli. [ABSTRACT FROM AUTHOR]

Cytochrome P450c17 ( CYP17, 17α-hydroxylase/17,20-lyase) is a critical enzyme in the production of androgens and estrogens in vertebrates. A 2102 bp full-length cDNA of P450c17-II ( CYP17A2) has been isolated from the ovary of half-smooth tongue sole, C ynoglossus semilaevis which encodes 524 amino acids. The putative P450c17- II enzyme shares higher sequence identity with those of teleosts than with P450c17- I of vertebrate. The similarity between the two types of tongue sole P450c17 was 48%.Semi-quantitative RT- PCR analysis of spatial expression showed the enzyme was specifically expressed in the ovary and the head kidney. However, temporal expression shows that P450c17- II can be found in the brain. Furthermore, temporal expression pattern of P450c17- II in ovary and brain revealed developmental stage-dependency, and ovary P450c17- II expressed remarkably throughout the whole reproductive cycle. Otherwise, the expression pattern of P450c17- II in head kidney indicated negative ovary development-dependence. In addition, combined with our data on P450c17- I, T and E2 levels, the results further endorse the critical role of P450c17- II during shift in steroidogenesis, suggesting that P450c17- I and - II may act together to this physiological process. Based on the present study, we indicate an important role for P450c17- II during ovarian development. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Estrogen receptor (ERalpha) modifies the expression of genes involved in cell growth, proliferation and differentiation through binding to estrogen response elements (EREs) located in a number of gene promoters, so the ERalpha gene is considered as an important factor affecting reproductive endocrinology in Japanese flounder (Paralichthys olivaceus). In this study, twelve single nucleotide polymorphisms (SNPs) within eight CDS exons and 1 kb of 3'-UTR of the ERalpha gene were tested to association with four reproductive traits in a population of 119 Japanese flounder individuals with polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP). The association analysis of SNPs within Japanese flounder ERalpha gene with the reproductive traits was carried out using General Linear Model (GLM) estimation. Results indicated that two SNPs in the exon4 of ERalpha gene, P1 (A803G and C864T), were significantly associated with hepatosomatic index (HSI) (P<0.05) in female Japanese flounder. Other ten SNPs in 3'-UTR associated to serum 17beta-estradiol (E(2)) and HSI showed that P2 (A1982T) was significantly associated with E(2) (P<0.01) and P3 (A2149G, 2181TTACAAG2182 insertion or deletion, T2324G, A2359G and G2391A) was significantly associated with HSI (P<0.05) in female Japanese flounder. However, P2 (A1982T) and P4 (G2256T, T2294C, T2309G and A2333T) had significant effects on E(2) (P<0.05 and P<0.01, respectively) in male Japanese flounder. In addition, there were significant associations between diplotype D1 based on fourteen SNPs and reproductive traits. The genetic effects for HSI (female) or E(2) (male) of diplotype D1 were significantly higher than those of other eight diplotypes (P<0.05), respectively. Our findings implied that P1 of ERalpha gene affecting the reproductive traits could be a potential QTN (quantitative trait nucleotide) which would be useful genetic marker in the selection of some reproductive traits for its in Japanese flounder.