Fig. 2
From: Single-cell CAS-seq reveals a class of short PIWI-interacting RNAs in human oocytes
Characteristics of novel 20-nucleotide (nt) small RNAs (oocyte short-PIWI-interacting RNAs (os-piRNAs)) in human oocytes. a Composition of small RNA categories according to their length distributions in both human and mouse oocytes. The length of os-piRNAs in human oocytes was ~2 nt shorter than that of mouse endo-small interfering RNAs (endo-siRNAs). b The relative nucleotide composition of piRNAs, endo-siRNAs, and os-piRNAs in a. Both os-piRNAs and the 30-nt piRNAs in human oocytes, as well as the piRNAs in mouse oocytes, have a preference of 1U and 10A in nucleotide compositions. c Length distribution of 5′ overlaps between small RNA pairs mapped to the opposite genomic strands of the same locus. The spike at 10 nt indicates the signature of a 10-nt 5′-end overlap between the partially complementary small RNA pairs. An example of an os-piRNA pair with a 10-nt 5′-end overlap signature is shown. d The proportion of complementary reads with a 2-nt 3′ overhang in human os-piRNAs was significantly lower than that in mouse endo-siRNAs. The average result in six human/mouse oocyte samples is shown in a–d, and the error bars in c, d represent the standard deviation. e Distribution of os-piRNA clusters on human chromosomes (top) and an instance of an os-piRNA cluster (bottom). The positive and negative numbers of the vertical axis represent the expression on the plus and minus strands, respectively. f Human os-piRNAs were more prone to be derived from single-stranded precursors compared to mouse endo-siRNAs. Strand bias in six replicate samples is shown. Source data of a–f are provided in the Source Data file
