THE XBAI-BLNI-CEUI GENOMIC CLEAVAGE MAP OF SALMONELLA-PARATYPHI B

The genomic cleavage map of Salmonella paratyphi B was determined thro ugh digestion with endonucleases and separation of the fragments by pu lsed-field gel electrophoresis. The chromosome has 19 XbaI sites, 10 B lnI sites, and 7 CeuI sites. The fragments were arranged in order thro ugh excision of fragments from the gel, redigestion with a second enzy me, end labelling with P-32, and reelectrophoresis. Tn10 transposons i nserted in 61 different genes of S. typhimurium LT2 were transduced by use of bacteriophage P22 into S. paratyphi B. The locations of Tn10 i nsertions on the chromosome of S. paratyphi B were determined by use o f,E;bal and BlnI sites in Tn10, revealing the positions of genes with Tn10 insertions in S. paratyphi B. All seven CeuI sites (in rrl genes for 23S rRNA) and most of the XbaI and BlnI sites in rm genes for Glt- tRNA are conserved, but only about half of the XbaI and BlnI sites out side rm genes are conserved. Gene order is identical in the 68 genes t hat we could compare between S. paratyphi B and S. typhimurium LT2, an d the lengths of intervals between the genes are often the same, but t here are several instances of differences in interval lengths, indicat ing that insertions or deletions of DNA have occurred during the evolu tionary divergence of these bacteria.