GSE171951
Maternal Piwi regulates primordial germ cells to ensure the fertility of female progeny in Drosophila
PIWI proteins and their associated small noncoding piRNAs, which guide PIWI to target RNAs by base-pairing, are among the maternal components deposited into the germline of the early embryo in Drosophila. Piwi has been extensively studied in the adult ovary and testis, where it is required for transposon suppression, germline stem cell self-renewal, and fertility. Consequently, loss of Piwi in the adult ovary using piwi-null alleles or knockdown from early oogenesis results in complete sterility, limiting investigation into possible embryonic functions of maternal Piwi. In this study, we show that the maternal Piwi protein persists in the embryonic germline through gonad coalescence, suggesting that maternal Piwi can regulate germline development beyond early embryogenesis. Using a maternal knockdown strategy, we find that maternal Piwi is required for the fertility and normal gonad morphology of female, but not male, progeny. Following maternal Piwi knockdown, transposons were mildly derepressed in the early embryo but were fully repressed in the adult ovaries of progeny. Furthermore, the maternal piRNA pool is diminished, reducing the capacity of the PIWI/piRNA complex to target some zygotic genes during embryogenesis. Examination of embryonic germ cell proliferation and gene expression in the adult ovary showed that the germline of female progeny is partially masculinized upon maternal Piwi knockdown . This reveals a novel role for maternal Piwi in the germline development of female progeny and suggests that the PIWI/piRNA pathway is involved in germline sex determination in Drosophila. Overall design: Total RNA-seq and Small RNA-seq of embryos depleted of maternal Piwi