The sensitive period for male-to-female sex reversal begins at the embryonic stage in the Nile tilapia and is associated with the sexual genotype

Gennotte Vincent, Mélard Charles, D'Cotta Helena, Baroiller Jean-François, Rougeot Carole. 2014. The sensitive period for male-to-female sex reversal begins at the embryonic stage in the Nile tilapia and is associated with the sexual genotype. Molecular Reproduction and Development, 81 (12) : 1146-1158.

Quartile : Q2, Sujet : REPRODUCTIVE BIOLOGY / Quartile : Q3, Sujet : BIOCHEMISTRY & MOLECULAR BIOLOGY / Quartile : Q3, Sujet : DEVELOPMENTAL BIOLOGY / Quartile : Q3, Sujet : CELL BIOLOGY

Résumé : In this study, we sought to determine the mechanism of early sex reversal in a teleost by applying 4 hr feminization treatments to XY (17α-ethynylestradiol 2000 µgL -1) and YY (6500 µgL -1) Nile tilapia embryos on the first day post-fertilization (dpf). We then searched for changes in the expression profiles of some sex-differentiating genes in the brain (cyp19a1b, foxl2, and amh) and in sex steroids (testosterone, 17b-estradiol, and 11-ketotestosterone) concentrations during embryogenesis and gonad differentiation. No sex reversal was observed in YY individuals, whereas sex-reversal rates in XY progeny ranged from 0-60%. These results, together with the clearance profile of 17α-ethynylestradiol, confirmed the existence of an early sensitive period for sex determination that encompasses embryonic and larval development and is active prior to any sign of gonad differentiation. Estrogen treatment induced elevated expression of cyp19a1b and higher testosterone and 17β-estradiol concentrations at 4 dpf in both XY and YY individuals. foxl2 and amh were repressed at 4 dpf and their expression levels were not different between treated and control groups at 14 dpf, suggesting that foxl2 did not control cyp19a1b in the brains of tilapia embryos. Increased cyp19a1b expression in treated embryos could reflect early brain sexualization, although this difference alone cannot account for the observed sex reversal as the treatment was ineffective in YY individuals. The differential sensitivity of XY and YY genotypes to embryonic induced-feminization suggests that a sex determinant on the sex chromosomes, such as a Y repressor or an X activator, may influence sex reversal during the first steps of tilapia embryogenesis.

Classification Agris : M12 - Production de l'aquaculture
L53 - Physiologie animale - Reproduction
L10 - Génétique et amélioration des animaux

Champ stratégique Cirad : Axe 1 (2014-2018) - Agriculture écologiquement intensive

Auteurs et affiliations

• Gennotte Vincent, Centre de Recherches et de Formation en Aquaculture (BEL)
• Mélard Charles, Centre de Recherches et de Formation en Aquaculture (BEL)
• D'Cotta Helena, CIRAD-PERSYST-UMR INTREPID (FRA) ORCID: 0000-0003-2739-3476
• Baroiller Jean-François, CIRAD-PERSYST-UMR INTREPID (FRA) ORCID: 0000-0002-0992-1725
• Rougeot Carole, Centre de Recherches et de Formation en Aquaculture (BEL)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/575011/)

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