FIG. 4.

Plasmid patterns. Agarose gel electrophoresis of plasmid preparations of E. hirae S185R, S185, and SS22. (A and C) Detection with ethidium bromide on 0.8 and 1% (wt/vol) agarose gels, respectively. (B) Southern blot of the gel described in panel A with oligonucleotide O1 (pbp3r). Controls were pDML501 with a 4.5-kb NcoI insert containing pbp3r and pDML540 with a 7-kb EcoRI insert containing pbp5. The upper bands observed in the pDML501 preparation are probably another form and dimers of pDML501, because restrictions yielded only the 4.5-kb insert and the pBR325 vector. Standards were linear bacteriophage λ HindIII fragments and supercoiled pIP964 (a generous gift from T. Horaud, Pasteur Institute, Paris, France). Ch, linearized chromosomal DNA contaminant.