FIG. 4.

oxyS and soxS induction by hydrogen peroxide and paraquat. The figure shows the results of primer extension assays of oxyS and soxS transcript levels in wild-type (MC4100) cells grown in LB medium. An exponential-phase culture was split into aliquots: one aliquot was left untreated, and the other aliquots were exposed to the indicated concentrations of hydrogen peroxide and paraquat. The cells were harvested after 5 min, total RNA was isolated, and primer extension assays were carried out with primer 188 specific to oxyS and primer 823 specific to soxS.