DIFFERENTIAL EXPRESSION OF GENES FOR AROMATASE AND ESTROGEN-RECEPTOR DURING THE GONADAL DEVELOPMENT IN CHICKEN EMBRYOS

Citation
O. Nakabayashi et al., DIFFERENTIAL EXPRESSION OF GENES FOR AROMATASE AND ESTROGEN-RECEPTOR DURING THE GONADAL DEVELOPMENT IN CHICKEN EMBRYOS, Journal of molecular endocrinology, 20(2), 1998, pp. 193-202
Citations number
29
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Endocrynology & Metabolism
ISSN journal
0952-5041
Volume
20
Issue
2
Year of publication
1998
Pages
193 - 202
Database
ISI
SICI code
0952-5041(1998)20:2<193:DEOGFA>2.0.ZU;2-N
Abstract
In birds, differentiation of embryonic gonads is not as strictly deter mined by the genetic sex as it is in mammals, and can be influenced by early manipulation with a sex steroid hormone. Thus administration of an aromatase inhibitor induces testis development in the genetic fema le, and administration of estrogen induces a left ovotestis in the gen etic male embryo. Another feature of avian gonadogenesis is that only the left ovary develops in most species. Molecular mechanisms underlyi ng these features at the lei el of gene expression have not been eluci dated. In this paper, we present evidence that a gene for aromatase cy tochrome P-450, an enzyme required for the last step in the synthesis of estradiol-17 beta, is expressed in medullae of the left and right g onads of a female chicken embryo, but not in those of a male chicken e mbryo, and that an estrogen receptor gene is expressed only in epithel ium (and cortex later, in the female) of the left, not the right, gona d of both sexes, but the expression in the male left gonad is temporar y and restricted to an early stage of des development. Differential ex pression of these two genes serves well to explain the above features of gonadal development in birds. Furthermore, in ovo administration of estradiol-17 beta from the 5th to the 14th day of incubation does not cause expression of the estrogen receptor gene in the right gonad of chicken embryos of either sex, suggesting that the absence of expressi on of the estrogen receptor gene in the right gonad is not the result of down-regulation, but may be regarded as an important cause of the u nilateral ovarian development.