Expression of P450 aromatase protein in developing and in sex-reversed gonads of the XX/XY type of the frog Rana rugosa

Takashi Kato, K. Matsui, M. Takase, M. Kobayashi, M. Nakamura

    Research output: Contribution to journalArticle

    36 Citations (Scopus)

    Abstract

    Gonadal differentiation in some species of amphibians is sensitive to steroids. The phenotypic sex of XX/XY-type frogs such as Rana rugosa can be reversed from female to male by injection of testosterone into tadpoles, but little is known about the molecular mechanism of this sex reversal. To elucidate the mechanism of the sex differentiation, we examined the role of P450 aromatase (P450arom), an enzyme that converts testosterone to estrogen, during gonadal differentiation of amphibians. In this study, we first cloned a P450arom cDNA homolog of the frog R. rugosa and analyzed by RT-PCR its expression profile in developing and in female-to-male sex-reversed gonads. P450arom expression was observed in the gonad of tadpoles during ovarian differentiation and became much stronger in the developing ovary in which only immature oocytes were observed. However, its expression declined significantly in the ovary of frogs 2 months after metamorphosis, when oocytes were growing; and it was no longer seen in adult ovaries. By RT-PCR, we also examined the expression of P450arom and SF-1 (steroidogenic factor-1; the orphan nuclear receptor) in the female-to-male sex-reversed gonad. The level of P450arom mRNA was high in the ovary, but it declined rapidly after the injection of testosterone. In contrast, no change in the SF-1 (also known as Ad4BP) expression was observed. Moreover, to identify the type(s) of cells expressing P450arom protein, we performed immunostaining with an antibody against frog P450arom protein. Cells giving positive signals were observed around oocytes in the ovary of frogs 1 month after metamorphosis. They were identified as follicle cells by both light and electron microscopy. The results, taken together, indicate that P450arom protein is synthesized in follicle cells and that P450arom is very much involved in ovarian differentiation in R. rugosa.

    Original languageEnglish
    Pages (from-to)227-236
    Number of pages10
    JournalGeneral and Comparative Endocrinology
    Volume137
    Issue number3
    DOIs
    Publication statusPublished - 2004 Jul

    Fingerprint

    Ranidae
    Aromatase
    Gonads
    Anura
    gonads
    frogs
    gender
    Ovary
    Proteins
    proteins
    testosterone
    Oocytes
    Testosterone
    oocytes
    Amphibians
    tadpoles
    metamorphosis
    Larva
    amphibians
    reverse transcriptase polymerase chain reaction

    Keywords

    • Frog
    • Granulose cell
    • Immunostaining
    • Ovary
    • P450 aromatase
    • Sex-reversal

    ASJC Scopus subject areas

    • Endocrinology

    Cite this

    Expression of P450 aromatase protein in developing and in sex-reversed gonads of the XX/XY type of the frog Rana rugosa. / Kato, Takashi; Matsui, K.; Takase, M.; Kobayashi, M.; Nakamura, M.

    In: General and Comparative Endocrinology, Vol. 137, No. 3, 07.2004, p. 227-236.

    Research output: Contribution to journalArticle

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