A complementation analysis of transfer-deficient mutants of RP1 will be completed. Polar insertion mutants will be used to define the operon structure of the transfer region, and deletion mutants to give a genetic map of the transfer genes. The physical and genetic extents of the deletions will be compared to locate the transfer genes on the physical map of RP1. Complementation of representative point mutants by other enterobacterial and pseudomonas plasmids will be determined. Transducing phages carrying transfer and/or antibiotic resistance genes will be isolated and characterized genetically and physically.