Crosstalk between retinoic acid and sex-related genes controls germ cell fate and gametogenesis in Medaka
Résumé
Sex determination (SD) is a highly diverse and complex mechanism. In vertebrates,
one of the first morphological differences between the sexes is the timing of initiation
of the first meiosis, where its initiation occurs first in female and later in male. Thus,
SD is intimately related to the responsiveness of the germ cells to undergo meiosis
in a sex-specific manner. In some vertebrates, it has been reported that the timing
for meiosis entry would be under control of retinoic acid (RA), through activation of
Stra8. In this study, we used a fish model species for sex determination and lacking
the stra8 gene, the Japanese medaka (Oryzias latipes), to investigate the connection
between RA and the sex determination pathway. Exogenous RA treatments act as a
stress factor inhibiting germ cell differentiation probably by activation of dmrt1a and
amh. Disruption of the RA degrading enzyme gene cyp26a1 induced precocious meiosis
and oogenesis in embryos/hatchlings of female and even some males. Transcriptome
analyzes of cyp26a1–/–adult gonads revealed upregulation of genes related to germ
cell differentiation and meiosis, in both ovaries and testes. Our findings show that germ
cells respond to RA in a stra8 independent model species. The responsiveness to RA is
conferred by sex-related genes, restricting its action to the sex differentiation period in
both sexes.
Domaines
Sciences du Vivant [q-bio]Origine | Fichiers produits par l'(les) auteur(s) |
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