Figure 4.

Base composition at the 5’-end of tSMS reads and preceding genomic regions. Read base composition is reported for the first position sequenced (position 1, bottom). In addition, the base composition of the genomic region is indicated for the two positions preceding the beginning of tSMS reads. The first (position −1, middle) corresponds to the locking site while the second (position −2, top) corresponds to the genomic position following the last nucleotide preserved in the ancient DNA template and located on the complementary strand (see Additional file 1, Figure S2).