Hi, I am sure somebody has done chemical mutagenesis (e.g. ENU), to introduce small but harmful mutation(s), followed by a second round of mutagenesis and selection for escape mutation(s) (suppressors) that make the double mutant as fit as the original organism/cell. Can you help me locate these data? Ideally whole genome sequencing of many such strains. I am trying to identify coevolving gene pairs, and so far have been using different species' genome sequence variations, but would like to include mutagenesis data in my analysis, especially if it is already out there somewhere. I can find data for whole genome sequences of strains after mutagenesis, but not exactly the experiment I am thinking of with an initial mutagenized unfit strain followed by subsequent doubly-mutagenized fit strains. Thanks!!