Extended Data Fig. 4: Sequence analysis and Ping-Pong signature of piRNAs in WT and Piwil1-deficient females.
From: The piRNA pathway is essential for generating functional oocytes in golden hamsters
(a) The piRNAs identified in oocytes and embryos collected from wild-type females showed three main peaks in their size distribution: 18–20-nucleotide (19-nucleotide piRNA), 22–24-nucleotide (23-nucleotide piRNA), and 28–30-nucleotide (29-nucleotide piRNA). All three piRNA populations preferentially carried a 5′ uracil (U). Oocytes and embryos collected from Piwil1m1/m1 females only expressed 19-nucleotide piRNAs, which showed a strong preference for a 5′ U. Piwil1m1/m1 indicates Piwil1-deficient oocytes or maternal Piwil1-deficient embryos. Data shown were average value of biological replicates at each time point: n = 3 (PF), 3 (SF), 3 (GV), 3 (MII), 3 (9 h.p.e.a.), 6 (33 h.p.e.a.), 4 (44 h.p.e.a.) or 3 (52 h.p.e.a.) for WT; n = 2 (PF), 2 (SF), 2 (GV), 2 (MII), 3 (9 h.p.e.a.), 2 (33 h.p.e.a), 4 (44 h.p.e.a) or 4 (52 h.p.e.a) for Piwil1 mutants. (b) Sequence analysis of piRNAs bound to PIWIL1 and PIWIL3 in MII oocytes. (c) The 5’-5’ overlap between sense- and antisense strands of TE-derived piRNAs bound to PIWIL1 or PIWIL3 were analyzed for the presence of Ping-Pong signatures. The number of pairs of piRNA reads at each position is plotted. Significance of 10-nucleotide overlap (‘Ping-Pong’) was determined based on Z score; a Z score > 1.96 corresponds to p-value < 0.05.
