[The role of the chromosomal Thr-Leu segment of E. coli K-12 in the expression of the fin-V transfer inhibition system of the F-like plasmid pAP53].

The role E. coli K-12 cell chromosome genetic region (tis-region) in expression of fin V-transfer inhibition system of F-like plasmid pAP53 was shown. The results obtained testify the linkage of tis region and Thr-Leu chromosomal segment.

[Mutations of the genetic region Fin of the F-like plasmid pAP18-1].

With help of nitrosoguanidine 60 mutants of F-like plasmids pAP18-1 drd::Tn 5 and pAP18-1::Tn 9 were induced which determined resistance of E. coli cells of specific phage MS2. Mutational changes in fin-locus of those plasmids were accompanied by phenotypic reversion Fin(-)-Fin+.