Figure 4

A piRNA cluster giving rise to both piRNAs and pr19RNAs A) A bidirectional piRNA cluster is presented (NCBI37/mm9 coordinates: chr6:127,734,347-127,787,210). The coverage of piRNAs-sized reads (24-30nt) and 19mers (with A 10 nt downstream) is visualised by wiggle-plots with reads mapped from left to right above the x-axis and reads mapped from right to left below. Only uniquely mapping reads are plotted. The position of repetitive elements, adapted from the UCSC Genome Browser [15], is indicated below the plots. The approximate position of two PCR targets used for strand-specific real-time quantitative reverse transcription PCR (qRT-PCR) is also indicated. B) The abundance of the piRNA precursor transcript relative to that of an overlapping antisense precursor transcript is presented. The fold-difference was estimated by strand-specific qRT-PCR targeting two separate loci, as indicated.