ASW: a gene with conserved avian W-linkage and female specific expression in chick embryonic gonad

Michael O'Neill, Michele Binder, Craig Smith, Jane Andrews, Kirsty Reed, Matthijs Smith, Craig Millar, David Lambert, Andrew Sinclair

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Vertebrates exhibit a variety of sex determining mechanisms which fall broadly into two classes: environmental or genetic. In birds and mammals sex is determined by a genetic mechanism. In mammals males are the heterogametic sex (XY) with the Y chromosome acting as a dominant determiner of sex due to the action of the testis-determining factor, SRY. In birds females are the heterogametic sex (ZW); however, it is not known whether the W chromosome carries a dominant ovary-determining gene, or whether Z chromosome dosage determines sex. Using an experimental approach, which assumes only that the sex-determining event in birds is accompanied by sex-specific changes in gene expression, we have identified a novel gene, ASW (Avian Sex-specific W-linked). The putative protein for ASW is related to the HIT (histidine triad) family of proteins. ASW shows female-specific expression in genital ridges and maps to the chicken W chromosome. In addition, we show that, with the exception of ratites, ASW is linked to the W chromosome in each of 17 bird species from nine different families of the class Aves.

Original languageEnglish
Pages (from-to)243-249
Number of pages7
JournalDevelopment Genes and Evolution
Issue number5
Publication statusPublished - 13 May 2000
Externally publishedYes


  • Avian W-chromosome
  • Female-specific
  • Gene expression
  • Gonad development

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