Is a sex-determining gene(s) necessary for sex-determination in amphibians? Steroid hormones may be the key factor

M. Nakamura

    Research output: Contribution to journalArticle

    17 Citations (Scopus)

    Abstract

    Amphibians have 2 genetic sex-determining systems, one with male (XX/XY) and one with female (ZZ/ZW) heterogamety. While the ancestral state of sex-determination is thought to be female heterogamety, male and female heterogametic types were probably once interchangeable. The Japanese frog Rana rugosa has both XX/XY and ZZ/ZW systems within a single species in certain local populations. However, steroid hormones can alter the phenotypic sex epigenetically. In R. rugosa, steroidogenic enzyme expression starts before sex-determination in the indifferent gonad, and these enzymes become active in both male and female tadpoles. Androgens are produced in the indifferent gonad of male tadpoles at high levels, whereas estrogens are synthesized in females. In this regard, the observed enhanced expression of the hormone-metabolizing genes, CYP19 in the female gonad and CYP17 in males, may be crucial for sex-determination. Moreover, with FSH known to increase estrogen synthesis in the vertebrate ovary, observed upregulation of FSH receptor (FSHR) expression in the indifferent gonad of female tadpoles is intriguing. These data suggest that steroid hormones could be crucial for sex-determination in R. rugosa, with the consequence that upregulation of CYP19 and FSHR expression is necessary for female and CYP17 for male sex-determination.

    Original languageEnglish
    Pages (from-to)104-114
    Number of pages11
    JournalSexual Development
    Volume7
    Issue number1-3
    DOIs
    Publication statusPublished - 2012 Dec

    Fingerprint

    Amphibians
    Steroids
    Hormones
    Gonads
    Genes
    FSH Receptors
    Steroid 17-alpha-Hydroxylase
    Larva
    Aromatase
    Estrogens
    Up-Regulation
    Ranidae
    Enzymes
    Anura
    Androgens
    Vertebrates
    Ovary
    Population

    Keywords

    • Amphibia
    • Rana rugosa
    • Sex chromosome
    • Sex reversal
    • Sex-determination
    • Steroid hormone

    ASJC Scopus subject areas

    • Developmental Biology
    • Embryology
    • Endocrinology, Diabetes and Metabolism

    Cite this

    Is a sex-determining gene(s) necessary for sex-determination in amphibians? Steroid hormones may be the key factor. / Nakamura, M.

    In: Sexual Development, Vol. 7, No. 1-3, 12.2012, p. 104-114.

    Research output: Contribution to journalArticle

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