title: The primary sex determination signal of Drosophila acts at the level of transcription.
abstract: For Drosophila, the choice between male and female development is made by the switch gene, Sxl, in response to the X:A ratio. Once Sxl is turned on in females, it actively maintains the determined state, independent of the X:A signal, by a positive autoregulatory feedback loop in which Sxl proteins direct the female-specific splicing of Sxl transcripts. In this paper we have investigated the mechanism controlling pathway initiation. Our results suggest a two-step model for the initial activation of Sxl in females. In the first step, a special class of Sxl mRNAs is expressed in female embryos from an early promoter that responds to the genes signaling the X:A ratio. The proteins produced from these early mRNAs then initiate the autoregulatory loop by directing the female-specific processing of transcripts from the late Sxl promoter.
authors.affiliation: Department of Biology, Princeton University, New Jersey 08544.
authors.forename: L N
authors.initials: LN
authors.lastname: Keyes
authors.forename: T W
authors.initials: TW
authors.lastname: Cline
authors.forename: P
authors.initials: P
authors.lastname: Schedl
mesh_terms: D000818:Animals; D001483:Base Sequence; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D005246:Feedback; D005786:Gene Expression Regulation / Q000235:genetics; D008969:Molecular Sequence Data; D012326:RNA Splicing; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D012732:Sex Determination Analysis; D015534:Trans-Activators; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D015534:Trans-Activators