Article (Scientific journals)
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 et al.
2014In Molecular Reproduction and Development, 81, p. 1146-1158
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Keywords :
sex determination; brain; aromatase; genes; steroids
Abstract :
[en] 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 mg L-1) and YY (6500 mg L-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, 17β-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.
Research center :
AFFISH-RC - Applied and Fundamental FISH Research Center - ULiège
Disciplines :
Genetics & genetic processes
Author, co-author :
Gennotte, Vincent ;  Université de Liège - ULiège > Centre de formation et de recherche en aquaculture (CEFRA)
Mélard, Charles ;  Université de Liège - ULiège > Centre de formation et de recherche en aquaculture (CEFRA)
D'Cotta, Helena;  Cirad > UMR Intrepid > Persyst
Baroiller, Jean-François;  Cirad > UMR Intrepid > Persyst
Rougeot, Carole ;  Université de Liège - ULiège > Centre de formation et de recherche en aquaculture (CEFRA)
Language :
English
Title :
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
Publication date :
2014
Journal title :
Molecular Reproduction and Development
ISSN :
1040-452X
eISSN :
1098-2795
Publisher :
Wiley Liss, Inc., New York, United States - New York
Volume :
81
Pages :
1146-1158
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture [BE]
ULiège - Université de Liège [BE]
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since 22 October 2014

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