Hierarchical clustering analysis of genes affected by oxidant or found to be regulated by PerR or Fur. From left to right: the first four columns represent changes in the transcriptome of the wild-type C. jejuni strain grown in MEMα medium in response to a 10-minute exposure to cumene hydroperoxide (labeled CHP), menadione (labeled MND), hydrogen peroxide (labeled H2O2), and H2O2 in the presence of iron (labeled H2O2 + Fe). The next four columns represent the changes in transcript level in the wild-type strain compared to the ΔperR mutant grown in MEMα medium determined 15 minutes after the addition of ferrous sulfate (labeled [perR + WT]/[WT + Fe]), in MEMα medium (labeled perR/WT), 15 minutes after the addition of ferrous sulfate followed by a 10-minute exposure to H2O2 (labeled [perR + Fe + H2O2]/[WT + Fe + H2O2]), and 10 minutes after exposure to H2O2 (labeled [perR + H2O2]/[WT + H2O2]). The last two columns represent the changes in transcript levels in the wild-type C. jejuni strain compared to the Δfur mutant grown to mid-log phase in MEMα medium (labeled fur/WT) and 15 minutes after addition of ferrous sulfate (labeled [fur + Fe]/[WT +Fe]). The Fur regulon was previously reported in Palyada et al. . The intensity of red and green indicates the degree of change, as represented by the scale at the bottom. Genes in boldface are further discussed in the text.