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Parkhurst, S M; Bopp, D; Ish-Horowicz, D (1990). X:A ratio, the primary sex-determining signal in Drosophila, is transduced by helix-loop-helix proteins. Cell, 63(6):1179-1191.

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Drosophila determines its sex by "counting" X chromosomes. We show that premature expression of the pair-rule segmentation gene hairy interferes with this process, resulting in female-specific lethality by inhibiting initiation of the master control gene Sex-lethal (Sxl). The female-specific lethality can be suppressed by a constitutive Sxl allele or by extra copies of X-linked "counting elements." These results are best explained by competition between hairy and other helix-loop-helix transcription factors that act in chromosome counting. We have confirmed this model by showing that misexpression of the achaete-scute T4 gene induces ectopic Sxl expression and male-specific lethality, confirming that achaete-scute T4 is the sisterless-b counting element. We propose that X chromosomes are counted through heterodimers of helix-loop-helix transcription factors that act synergistically to initiate Sxl expression.


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Additional indexing

Item Type:Journal Article, refereed
Communities & Collections:07 Faculty of Science > Institute of Molecular Life Sciences
Dewey Decimal Classification:570 Life sciences; biology
Date:21 December 1990
Deposited On:11 Feb 2008 12:13
Last Modified:05 Apr 2016 12:12
Publisher DOI:10.1016/0092-8674(90)90414-A
PubMed ID:2124516

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