LOCATION OF IS200 ON THE GENOMIC CLEAVAGE MAP OF SALMONELLA-TYPHIMURIUM LT2

Locations of six Tn10s, closely linked to each of the six IS200s on th e genomic cleavage map of Salmonella typhimurium LT2, were determined by digestion with XbaI and BlnI and separation of the fragments by pul sed-field gel electrophoresis; the locations were then further defined by P22-mediated joint transduction. The orientation of each IS200 wit h respect to its linked Tn10 was determined by Southern blotting. The locations of IS200-I, IS200-III, and IS200-V were confirmed to be clos e to sufD, melB, and purC, as previously indicated. IS200-II is jointl y transduced with cysG. IS200-IV is near fliA; the linked Tn10 is inse rted in fli, making the strain nonmotile. IS200-VI is jointly transduc ed with aspC but not with aroA. IS200 is transposed to a seventh site in some strains, while remaining in the other six locations described above. These data indicate that genome analysis by pulsed-field gel el ectrophoresis can locate the positions of Tn10s with accuracy sufficie nt to predict P22-mediated joint transduction.