Diagram of the 5' junction sequences of the somatic R2 insertions with the 28S gene. Putative somatic insertions such as those shown in Figure 1C, D were excised from a gel, re-amplified with the same PCR primers, purified on a second gel and subjected to double-stranded DNA sequencing. The 28S gene sequence is shown at the top of the figure. Short regions upstream and downstream of the R2 insertion site (arrow) are not shown because no R2 junctions occurred in these areas. For each junction those sequences corresponding to R2 sequences have been highlighted with tan shaded boxes. Those nucleotides that could correspond to either the 28S sequence or R2 (described as microidentities in the text) have been indicated with a blue box. Those sequences that do not correspond to either the 28S gene or R2 (described as non-templated nucleotides in the text) are indicated with an orange box. The number at each junction corresponds to the first nucleotide of the R2 element, based on the consensus Drosophila simulans R2 sequence .