Figure 1.

piRNAs associated with Aub and Piwi in fly ovary are methylated at their 3′ ends. (A) piRNA associated with Aub and Piwi in fly ovary were subjected to periodate oxidation/β-elimination chemical reactions. In both cases, piRNAs did not gain mobility, indicating that these piRNAs with Aub and Piwi were modified at their 3′ ends. Under these conditions, a synthetic 21-nt small RNA (luc guide siRNA) (Okamura et al. 2004) gained mobility by nearly 2 nt, a feature of RNAs bearing a 2′-, 3′-terminal-cis-diol group at the last nucleotide (Hutvagner et al. 2001). (B) miRNAs associated with AGO1 in fly ovary show that they are not modified at their 3′ ends, in contrast to plant miRNAs (Yu et al. 2005).