CONTROL OF MALE SEXUAL-BEHAVIOR AND SEXUAL ORIENTATION IN DROSOPHILA BY THE FRUITLESS GENE

Sexual orientation and courtship behavior in Drosophila are regulated by fruitless (fru), the first gene in a branch of the sex-determinatio n hierarchy functioning specifically in the central nervous system (CN S). The phenotypes of new fru mutants encompass nearly all aspects of male sexual behavior. Alternative splicing of fru transcripts produces sex-specific proteins belonging to the BTB-ZF family of transcription al regulators. The sex-specific fru products are produced in only abou t 500 of the 10(5) neurons that comprise the CNS. The properties of ne urons expressing these fru products suggest that fru specifies the fat es or activities of neurons that carry out higher order control functi ons to elicit and coordinate the activities comprising male courtship behavior.