Nucleotides flanking the base inducing Trp+ reversion are usually incorporated in Trp+ revertants.

<p>Oligo N of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042905#pone-0042905-g002" target="_blank">Fig. 2</a> was transformed into G148Cm strains of the indicated genotype and Trp+ revertants sequenced to determine which oligo-induced mutations were present in each revertant, with the distance indicated from the 5′ end of the oligo. The indicated percentages are determined from approximately 48 revertants of each genotype. Trp+ revertants containing only the mutation at position 21 were assumed to be spontaneous revertants and were observed, rarely, and were not counted. In all experiments, oligos anneal to the leading strand of replication in the F orientation, and to the lagging strand in the R orientation.