Unbound MEDLINE

High temperature induces cyp26b1 mRNA expression and delays meiotic initiation of germ cells by increasing cortisol levels during gonadal sex differentiation in Japanese flounder.

Abstract

The Japanese flounder (Paralichthys olivaceus) is a teleost fish with an XX/XY sex determination system. XX flounder can be induced to develop into phenotypic females or males, by rearing them at 18°C or 27°C, respectively, during the sex differentiation period. Therefore, the flounder provides an excellent model to study the molecular mechanisms underlying temperature-dependent sex determination. We previously showed that cortisol, the major glucocorticoid produced by the interrenal cells in teleosts, causes female-to-male sex reversal by directly suppressing mRNA expression of ovary-type aromatase (cyp19a1), a steroidogenic enzyme responsible for the conversion of androgens to estrogens in the gonads. Furthermore, an inhibitor of cortisol synthesis prevented masculinization of XX flounder at 27°C, suggesting that masculinization by high temperature is due to the suppression of cyp19a1 mRNA expression by elevated cortisol levels during gonadal sex differentiation in the flounder. In the present study, we found that exposure to high temperature during gonadal sex differentiation upregulates the mRNA expression of retinoid-degrading enzyme (cyp26b1) concomitantly with masculinization of XX gonads and delays meiotic initiation of germ cells. We also found that cortisol induces cyp26b1 mRNA expression and suppresses specific meiotic marker synaptonemal complex protein 3 (sycp3) mRNA expression in gonads during the sexual differentiation. In conclusion, these results suggest that exposure to high temperature induces cyp26b1 mRNA expression and delays meiotic initiation of germ cells by elevating cortisol levels during gonadal sex differentiation in Japanese flounder.

Links

  • Publisher Full Text

    • Authors

    Yamaguchi T, Kitano T

    Institution

    National Research Institute of Aquaculture, Fisheries Research Agency, Mie 516-0193, Japan.

    Source

    Biochemical and biophysical research communications 419:2 2012 Mar 9 pg 287-92

    MeSH

    Animals
    Cloning, Molecular
    Cytochrome P-450 Enzyme System
    Female
    Flounder
    Germ Cells
    Hot Temperature
    Hydrocortisone
    Male
    Meiosis
    Phylogeny
    RNA, Messenger
    Sex Characteristics
    Sex Differentiation
    Synaptonemal Complex

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22342721