Restriction banding patterns of total plasmid DNA from selected Salmonella isolates. Lanes 1 and 12, DNA marker fragments (sizes in kbp are indicated on the right edge of the gel); lanes 2 to 7, BamHI digestion of DNA from isolates S3 and S5 (RFP II), S78 and S80 (RFP I), and S13 and S14 (RFP III); lanes 8 and 9, EcoRI digestion of S16 and S18 (RFP IV); lanes 10 and 11, HindIII digestion of S27 and S28 (RFP V).