A Mutational Hotspot and Strong Selection Contribute to the Order of Mutations Selected for during Escherichia coli Adaptation to the Gut
Fig 3
The gat locus is a mutational hotspot.
The graph shows the log10 mutation rate (μ) (per locus, per generation) for each phenotype: gat-negative (grey bar) and furazolidone resistance (black bar) and their respective confidence intervals. Resistance to furazolidone is conferred by the inactivation of the nfsA gene. The values of μ were estimated by performing fluctuation assays and analyzing the results using the maximum likelihood approach implemented in FALCOR [25]. The mean frequency of spontaneous gat-negative mutants is ~300 times higher than the frequency of spontaneous resistants to furazolidone. After correcting for the difference between loci sizes the frequency of gat-negative phenotype is still ~38 times higher than the frequency of furazolidone resistance.