Membrane preparations from male, female and Hfr deletion mutant strains of E. coli are being analyzed as a means of identifying the products and functions of the genes in the F factor transfer operon of E. coli K12. Isolation of lambda transducing phage carrying Ftra operon genes is being attempted. Three phages which have complementing activity for Ftra J lac mutants are being characterized. A series of F lac mutants which are temperature sensitive in plasmid maintenance are being characterized.