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KMID : 0894520070110030195
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Development & Reproduction
2007 Volume.11 No. 3 p.195 ~ p.203
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Expression of Cytochrome P450 Aromatase Genes during Sex Differentiation in Korean Rockfish, Sebastes schlegeli
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Lee Chan-Hee
Kwon Joon-Yeong
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Abstract
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Sex determination and sex differentiation are influenced by genotype in many gonochoristic fish. Cytochrome P450 aromatase (CYP19) is the terminal enzyme in steridogenic pathway that converts androgens into estrogens. In this study, partial fragments of aromatase genes (ovarian aromatase, P450aromA and brain aromatase, P450aromB) were cloned and sequenced in Korean rockfish (Sebastes schlegeli), and gene specific primers were designed based on their sequences. Using these primers, aromatase gene expression during sex differentiation was investigated by RT-PCR. Expression of these aromatase genes were detected both in the head and body parts at 35 dab (days after birth). The number of fish that expressed the aromatase genes decreased at 52 dab, implying down-regulation of these genes. However, these genes were expressed at 59 dab in almost all fish studied here. The expression patterns of both genes are similar throughout the investigated period except for 45 dab where the expression of P450aromB was detected in more fish than that of P450aromA both in the head and body parts. Timing of sex differentiation in this species has been shown to be at around 50～65 dab by histological analysis. However, the results from this study suggest that sex differentiation of rockfish may take place 1～2 weeks earlier than the period proposed previously. The results also suggest that the mechanism of sex differentiation in viviparous fish may be similar to that in oviparous fish in terms of the importance of aromatase action during the critical period.
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KEYWORD
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Aromatase, Gene expression, Brain, Ovary, Sex differentiation, Viviparous, Rockfish, Sebastes schlegeli
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