Figure 1. Genetic organization of the antibiotic-resistance gene cluster of SGI1 of Salmonella enterica serotype Typhimurium DT 104. DR-L and DR-R are the left and right direct repeats, respectively, bracketing SGI1. Polymerase chain reactions (PCRs) used to assess the genetic organization of the antibiotic-resistance genes (PCRs floR, A, B, C, D, and E) and the SGI1 junctions to the chromosome (PCRs LJ and RJ for left and right junctions, respectively) are indicated. Abbreviations for restriction sites: X, XbaI; H, HindIII; Xh, XhoI.