Figure 2.

Perfect and complex short tandem duplications in primates and flies. (a) Exact tandem duplication. Replication errors following scenarios similar to the illustrated scheme will generate insertions that are flanked by their exact template. (b) Complex duplications. The 8 bp insertion illustrated lacks a simple tandem template, but can be divided into two parts, each of which have a perfect match in proximity to the insertion point (c) Reverse strand templates. The 8 bp insertion illustrated lacks a perfect or partial template in the vicinity of the insertion site. It does have a perfect template at the reverse strand, however, located 14 bp from the insertion point. (d) Fraction of insertions with perfect, partial and reverse template matches. Shown are the fractions of insertions that admitted a full tandem template, partial tandem template or reverse strand template, plotted as a function of the insertion length (see Materials and methods). Most of the remaining events (designated 'other') are likely to be artifacts (see text). Nt, nucleotides. (e) Spatial distribution of reverse strand templates. Shown is the distribution of relative positions of reverse strand templates for human/chimp insertions. The distribution was computed using insertions of at least 6 bp that lacked a tandem template in the plus strand but admitted a perfect reverse strand template.