Transcription of antisense GFP RNA from torimochi, an endogenous piRNA cluster. (Blue circle) Transcription start site (TSS) embedded with an endogenous piRNA cluster named torimochi. In #3, #5, and #8, this TSS-expressed antisense GFP fused with the torimochi-derived sequence. The fusion occurred in a splicing-dependent mechanism. We identified two types of “chimeric” piRNAs, which covered the junction between exogenous and endogenous sequences. Total abundances of each chimeric piRNA in three libraries are indicated. Chimeric piRNAs were not found in the WT BmN4-derived library. Density of piRNAs was normalized as described previously (Brennecke et al. 2007; Kawaoka et al. 2008b). See also Supplemental Figure S5.
