Females expressing nito^HMS00166 under the control of Scer\GAL4^dome-PG14 are partially lethal and the surviving adult females display sex-determination defects manifested by the appearance of sex combs on their forelegs.

Expression of nito^HMS00166 under the control of Scer\GAL4^{otu.T:Hsim\VP16} results in complete sterility in females. In wild-type ovarioles, two or three germ-line stem cells (GSCs) are located in the anterior tip of the germarium. Strikingly, the mutant ovarioles are filled with undifferentiated stem-cell-like cells, and nurse cells and oocytes are not formed. Further, stem-cell like cells associated with nito^HMS00166 ovaries retain their proliferative potential and show a tumor-like phenotype.

Expression of nito^HMS00166 using Scer\GAL4^dome-PG14, that drives expression in both the leg and genital discs, leads to the transformation of female tissues into that of males. This is evidenced by the appearance of dark, thickened bristles, the male sex combs, in the forelegs of nito^HMS00166 females. This phenotype is almost fully penetrant. In addition, there are strong abnormalities in the genitalia of the mutant females. The abnormalities include rotational defects and the absence of typical female external structures, such as vaginal bristles. Structures resembling those of males, such as penis apparatus and claspers can be identified in the mutants.

nito^HMS00166 expression driven by a ubiquitous driver such as Scer\GAL4^Act.PU or Scer\GAL4^tub.PU is associated with larval lethality.