Requirement of flex (female lethal on X) in the development of the female germ line of Drosophila melanogaster

Abstract

Drosophila melanogaster females homozygous for flex, an X- linked recessive mutation, do not survive. Hemizygous males are unaffected. Homozygous embryos appear to lack SXL, the product of the Sex-lethal (Sxl) gene, apparently as a result of disruption of Sxl splicing. It is known that both Sxl and its somatic splicing regulators [snf and fl(2)d] also function in the development of the female germ line. For this reason, we investigated the role of flex in the germ line by generating flex/flex clones in flex/+ females. Females carrying such clones in their germ lines do not lay eggs whereas females carrying flex eggs lay viable eggs. Additionally, DAPI staining of ovarioles showed that diploid germ cells that are homozygous mutant for flex do not complete oogenesis. These results indicate that the flex⁺ gene product may be required for the development of the female germ line.