Sex determination genes control the development of the Drosophila genital disc, modulating the response to Hedgehog, Wingless and Decapentaplegic signals

In both sexes, the Drosophila genital disc contains the female and male gen ital primordia, The sex determination gene doublesex controls which of thes e primordia will develop and which will be repressed. In females, the prese nce of Doublesex(F) product results in the development of the female genita l primordium and repression of the male primordium, In males, the presence of Doublesex(M) product results in the development and repression of the ma le and female genital primordia, respectively. This report shows that Doubl esex(F) prevents the induction of decapentaplegic by Hedgehog in the repres sed male primordium of female genital discs, whereas DoublesexM blocks the Wingless pathway in the repressed female primordium of male genital discs, It is also shown that DoublesexF is continuously required during female lar val development to prevent activation of decapentaplegic in the repressed m ale primordium, and during pupation for female genital cytodifferentiation, In males, however, it seems that Doublesex(M) is not continuously required during larval development for blocking the Wingless signaling pathway in t he female genital primordium, Furthermore, Doublesex(M) does not appear to be needed during pupation for male genital cytodifferentiation, Using dachs hund as a gene target for Decapentaplegic and Wingless signals, it was also found that Doublesex(M) and Doublesex(F) both positively and negatively co ntrol the response to these signals in male and female genitalia, respectiv ely. A model is presented for the dimorphic sexual development of the genit al primordium in which both DoublesexM and Doublesex(F) products play posit ive and negative roles.