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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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|
|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|
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