Figure 3. In Vivo in Flies, 2′-O-methylation Protects piRNAs against Destabilization by Complementary Sites.

Left, the predicted fraction of fly piRNAs bound to complementary sites in transcripts for different regions of the piRNA; a representative experiment from fly ovaries is shown. Right, the difference in the predicted median fraction bound for stable (≥ 80% of w¹¹¹⁸ levels in hen1^f00810) and unstable (≤ 20% of w¹¹¹⁸ levels in hen1^f00810) unmethylated piRNAs for contiguous complementarity starting at different piRNA nucleotides; data are for all possible permutations of biological replicates of fly ovaries (w¹¹¹⁸, n = 4; hen1^f00810, n = 2). Grey: data for piRNA regions for which the predicted median fraction bound did not decrease monotonically in the direction from unstable to stable piRNAs. The 95% confidence interval for the effect size of median difference was calculated with 10,000 bootstrapping iterations.