FIG. 3.

Density of piRNA matches to the consensus sequence of human-specific LINE-1 elements. To smooth the density, the plots were made using kernel density estimation with a Gaussian kernel instead of histograms. The blue (green) line shows the density of sense (antisense) piRNA matches to the LINE-1 element. The ∼1-kb region in the coding region of ORF2 that is depleted of piRNA matches is also depleted across all primate-specific LINE-1s in humans. There are 1,134 bases in LINE-1s that match piRNAs.