9122 Nucleic Acids Research, 2012, Vol. 40, No. 18 Figure 5. In vivo resistance of PT DNA to double-strand breakage caused by H2O2 Salmonella cells were incubated with increasing concentration of H2O2 for 2 h. DNA ds break damage was monitored using agarose gel electrophoresis in TAE buffer containing thiourea. W: wild-type; B–E: dptB–E mutant, respectively. DNA from dpt mutant dptC–E did not contain PT modiﬁcation, while DNA from dptB mutant contained increased PT modiﬁcation. The experiment was repeated at least ﬁve times. DNA smear is quantiﬁed by densitometry and estimations of the percentage are indicated below the gel panel. Figure 6. In vivo consumption of sulfur on the modiﬁed DNA. Salmonella (A) and its dptB mutant (B) were treated using increasing concentration of H2O2 for 2 h (0, 176, 528, 704 and 880 mM, respectively). Sulfur on genomic DNA was monitored by Dnd phenotype analysis (per-acetic acid treatment followed by electrophoresis using buffer contained thiourea). Upper panel: DNA samples not treated with per-acetic acid as a control.