The exuperantia gene is required for Drosophila spermatogenesis as well as anteroposterior polarity of the developing oocyte, and encodes overlapping sex-specific transcripts.

The Drosophila gene exuperantia (exu) is a maternal effect gene which is needed for proper localization of the bcd RNA during the formation of oocytes. We have extended the characterization of the exu phenotype and find that the gene functions in the male as well as the female germline. Six of seven exu alleles are male-sterile; mutant defects in spermatogenesis first appear during meiosis. A genetic analysis presented here shows that the exu gene does not encode a zygotic vital function. The isolation of two overlapping deficiencies that delete exu function localizes the gene cytologically to polytene bands 57A4-B1. We describe the molecular cloning and identification of the gene, and show that it encodes overlapping sex-specific transcripts of 2.9 kb in the male and 2.1 kb in the female. We also show that these two transcripts are limited in expression to the germline. We demonstrate that one allele, exuVL57, is a deletion of about 700 bp which results in a loss of both transcripts.