Proposed role of w chromosome inactivation and the absence of dosage compensation in avian sex determination

Chandra, Sharat H (1994) Proposed role of w chromosome inactivation and the absence of dosage compensation in avian sex determination. In: Proceedings of the Royal Society B: Biological Sciences, 258 (1351). pp. 79-82.

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Abstract

Three features of avian sex chromosomes - female heterogamety (ZZ male, ZW female), the apparently inactive state of the W chromosome, and dose-dependent expression of Z-linked genes - are examined in regard to their possible relation to sex determination. It is proposed that the W chromosome is facultatively heterochromatic and that the Z and W chromosomes carry one or more homologous sex-determination genes. The absence of dosage compensation in ZZ embryos, and W inactivation in ZW embryos, would then bring about a 2n(ZZ)-n(ZW) inequality in the effective copy number of such genes. The absence of dosage compensation of Z-linked genes in ZZ embryos is viewed as a means by which two copies of Z-W homologous sex determination genes are kept active to meet the requirements of testis determination. W inactivation may promote ovarian development by reducing the effective copy number of these genes from 2n to n. If there is a W-specific gene for femaleness, spread of heterochromatization to this gene in cells forming the right gonadal primordium may explain the latter's normally undifferentiated state; reversal of heterochromatization may similarly explain the development of the right gonad into a testis following left ovariectomy.

Item Type:	Journal Article
Publication:	Proceedings of the Royal Society B: Biological Sciences
Publisher:	The royal society
Additional Information:	Copyright of this article belongs to The royal society.
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	11 Apr 2011 04:22
Last Modified:	11 Apr 2011 04:22
URI:	http://eprints.iisc.ac.in/id/eprint/36709

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