FIG. 1.

The region of the C. diphtheriae C7(β) chromosome that includes sigB, dtxR, and galE is depicted. The region of dtxR deleted in the ΔdtxR strain is shown as a white inverted triangle within dtxR. The locations of the transposon insertions in C7(β)dtxR-TnUP labeled as 1 and in C7(β)dtxR-TnIN labeled as 2 are shown as vertical gray lines. The positions of primer binding sites are shown as small black arrows labeled A, B, C, D, E, F, G, a, b, c, and d. The fluorescent probes used in qRT-PCR assays are shown as striped rectangles labeled SB, DR, DG, and GE. The sequences of the primers and probes are given in Table 1.