TitleMolecular genetic dissection of the sex-specific and vital functions of the Drosophila melanogaster sex determination gene fruitless
Publication TypeJournal Article
Year of Publication2001
AuthorsAnand, A, Villella, A, Ryner, LC, Carlo, T, Goodwin, SF, Song, HJ, Gailey, DA, Morales, A, Hall, JC, Baker, BS, Taylor, BJ
Type of ArticleJournal Article

A multibranched hierarchy of regulatory genes controls all aspects of somatic sexual development in Drosophila melanogaster. One branch of this hierarchy is headed by the fruitless (fru) gene and functions in the central nervous system, where it is necessary for male courtship behavior as well as the differentiation of a male-specific abdominal structure, the muscle of Lawrence (MOL). A preliminary investigation of several of the mutations described here showed that the fru gene also has a sex-nonspecific vital function. The fru gene produces a complex set of transcripts through the use of four promoters and alternative splicing. Only the primary transcripts produced front the most distal (PI) promoter are sex specifically spliced under direction of the sex-determination hierarchy. We have analyzed eight new fi-it mutations, created by X-ray mutagenesis and P-element excision, to try to gain insight into the relationship of specific transcript classes to specific fru functions. Males that lack the Pl-derived fm transcript,, show a complete absence of sexual behavior, but tic, Other defects besides the loss of the MOL. Both males and females that have reduced levels of transcripts from the P3 promoter develop into adults but frequently die after failing to eclose. Analysis of the morphology and behavior of adult escapers showed that P3-encoded functions are required for the proper differentiation and eversion of imaginal discs. Furthermore, the reduction in the size of the neuromuscular junctions on abdominal muscles in these animals suggests that one of fru's sex-nonspecific functions involves general aspects of neuronal differentiation. In mutants that lack all fru transcripts as well its a small number of adjacent genes, animals die at all early pupal stage, indicating that fm's function is required only during late development. Thus, fru functions both ill the sex-determination regulatory hierarch), to control male sexual behavior through sex-specific transcripts and sex-nonspecifically to control the development of imaginal discs and motorneuronal synapses during adult development through sex-nonspecific transcript classes.

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