Molecular characterization of daughterless, a Drosophila sex determination gene with multiple roles in development.

The daughterless (da) gene in Drosophila acts both maternally and zygotically to provide essential functions during development. Maternal da+ expression is required by embryos for the regulation of sex determination and dosage compensation. Zygotic da+ expression is required throughout development--early for the formation of the peripheral nervous system and perhaps for the proper functioning of genes in heterochromatic regions of the genome; during larval stages for growth and differentiation of the future adult epidermis; and in the somatic part of the gonad of adult females for proper egg membrane synthesis. Here we describe the cloning of da by the transposon tagging approach as well as some aspects of the molecular characterization of wild-type and mutant alleles. Despite the multiple developmental roles of da, the organization and expression of this gene appear relatively simple at this level of analysis. The gene codes for two transcripts, present in both sexes and at all stages of development. The nucleotide sequence of a nearly full-length cDNA predicts a protein product of 710 amino acids that shares sequence similarity with the His-Pro repeat of the Drosophila genes bicoid and paired. Two partial-loss-of-function da mutations (one of which is temperature sensitive) appear to be caused by DNA insertions in the 5'-untranslated region of the gene.