65bp deletion and insertion of 5bp, resulting in a frame shift and truncation of the protein after amino acid 97 and the addition of 20 unrelated residues.
The male germline appears completely normal in stil5 adults.
Most ovaries of 5 day old homozygous females contain a few germ cells, while the number of ovaries completely lacking germ cells increases with age. Hemizygous stil4/Df(2R)vg135 females have a stronger phenotype, with a greater proportion of ovaries completely lacking germ cells. stil5/stil6 ovaries show sexual transformation, containing some male-like germ cells which resemble spermatocytes. Nurse cells and male-like cells are seen in the same ovary, suggesting that they are mosaic in terms of germ cell sexual identity. The dominant ovoD2 phenotype is not significantly enhanced by one copy of stil5.
Isolated in a screen for lethal or sterile mutations uncovered by Df(2R)vg135.