Document Detail

Environmental effects on fish sex determination and differentiation.
MedLine Citation:
PMID:  19684457     Owner:  NLM     Status:  MEDLINE    
Environmental factors affect the sex ratio of many gonochoristic fish species. They can either determine sex or influence sex differentiation. Temperature is the most common environmental cue affecting sex but density, pH and hypoxia have also been shown to influence the sex ratio of fish species from very divergent orders. Differential growth or developmental rate is suggested to influence sex differentiation in sea bass. Studies in most fish species used domestic strains reared under controlled conditions. In tilapia and sea bass, domestic stocks and field-collected populations showed similar patterns of thermosensitivity under controlled conditions. Genetic variability of thermosensitivity is seen between populations but also between families within the same population. Furthermore, in the Nile tilapia progeny testing of wild male breeders has strongly suggested the existence of XX males in 2 different natural populations. Tilapia and Atlantic silverside studies have shown that temperature sensitivity is a heritable trait which can respond to directional (tilapia) or frequency dependent selection. In tilapia, transitional forms within a genetic sex determination (GSD) and environmental sex determination (ESD) continuum seem to exist. Temperature regulates the expression of the ovarian-aromatase cyp19a1 which is consistently inhibited in temperature masculinized gonads. Foxl2 is suppressed before cyp19a1. Recent in vitro studies have shown that foxl2 activates cyp19a1, suggesting that temperature acts directly on foxl2 or further upstream. Dmrt1 up-regulation is correlated with temperature-induced male phenotypes. Temperature through apoptosis or germ cell proliferation could be a critical threshold for male or female sex differentiation.
J F Baroiller; H D'Cotta; E Saillant
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Publication Detail:
Type:  Journal Article; Review     Date:  2009-08-10
Journal Detail:
Title:  Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation     Volume:  3     ISSN:  1661-5433     ISO Abbreviation:  Sex Dev     Publication Date:  2009  
Date Detail:
Created Date:  2009-08-17     Completed Date:  2009-11-24     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101316472     Medline TA:  Sex Dev     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  118-35     Citation Subset:  IM    
Copyright Information:
2009 S. Karger AG, Basel.
CIRAD, Upr20, Dept. Persyst, Campus International de Baillarguet, Montpellier, France.
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MeSH Terms
Fishes / physiology*
Genetic Variation
Sex Determination (Genetics)*
Sex Differentiation / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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