Essential in the female germline for proper survival, sex determination and differentiation. Participates in the transcriptional activation of Otu. Does not regulate the expression of Ovo. Associates with decondensed chromatin, including sites of active transcription. Germ cells specific. Expressed in all germ cells. During the first instar larvae, it is expressed in all germ cells of both sexes. In third instar larvae, it decreases in male germ cells while it remains in female germ cells. In adult ovary, it is expressed in cells of the germarium, including the stem cells. In the early previtellogenic stages, it is highly expressed in the nurse cells. During vitellogenesis, it is not translocated into the maturing egg. In testes, it is only expressed during some steps of male germline differentiation. At the apex testis, it is expressed at low level in stem cells and dividing spermatogonia, while in newly formed 16-cell cysts of primary spermatocytes, it is transiently but strongly expressed before vanishing during spermatocyte growth phase. In embryos, it is expressed from stage 11 in the germ cell soon after their migration through the midgut epithelium.