[The transposon content of nonconjugated E. coli plasmids]. / O transpozonovom soderzhanii nekon''iugativnykh plazmid E. coli.

The search of nonconjugated plasmids in antibiotic-resistant cells of wild E. coli strains was performed and their transposon maintenance has been studied. The possibility of existence of some different nonconjugated plasmids in one bacterial cells was shown and each plasmid could carry the same transposon. Insertion of one transposon into the conjugated plasmid pAP42 resulted in numerous deletions in the genome of this plasmid.

[Identification of the number of mutant copies of the genetic transfer factor AP42]. / Identifikatsiia mutantov kopiinosti faktora geneticheskogo perenosa pAP42.

The copy number mutant of genetic transfer factor pAP42 (incFIX) was induced by the treatment of E. coli AP115 cells carrying the plasmid by N-methyl-N-nitro-N-nitrosoguanidine. The copy number mutant pAP42::Tn1cop1 is characterized by the increased copy number. The cells carrying the copy number mutant have a higher ampicillin resistance and higher beta-lactamase activity. Mutant plasmid pAP42: :Tn1cop1 is incompatible with plasmid pAP42 and compatible with plasmids of the other inc-groups of F-like plasmids.

[F-like genetic transfer factor pAP42]. / Izuchenie F-podobnogo faktora geneticheskogo perenosa pAP42.

Sensitivity of E. coli K-12 cells containing the transfer factor pAP42 to phages was examined to determine the frequency of the test factor transfer from one cell to another one. The data on the phage sensitivity and the frequency of transfer indicate that the test factor is F-like plasmid derepressed by the conjugation function. Study of incompatibility of the transfer factor pAP42 has shown its compatibility with plasmids of all 8 groups of F-incompatibility. This enables one to characterize this factor as a representative of a new FIX group of F-incompatibility.

[Characteristics and classification of plasmids of conditionally pathogenic E. coli according to their conjugative and mobilization capacity]. / Kharakteristika i klassifikatsiia plazmid uslovno-patogennykh E. coli po ikh kon"iugativnosti i mobilizationnoi sposobnosti.

A number of conjugative plasmids of opportunistic E. coli with molecular weights of 23.6--81.8 megadaltons have been studied. On the basis of the data thus obtained conjugative F-like R-plastmids have been subdivided into 2 groups characterized by the unsuppressed or suppressed manifestation of their functions. Individual conjugative plasmids have been found to differ in their capacity for mobilizing non-conjugative SuSm plasmid for transfer, which indicates the possibility of using this test for characterization and classification of plasmids, identified in natural bacterial population.

[Atypical incompatibility of the F-like factors of pA22-4, pAP39 and pA41 genetic transfer with the F-group incompatibility plasmids]. / Atipichnaia nesovmestimost' F-podobnykh faktorov geneticheskogo perenosa pA22-4, pAP39 i pA41 s plazmidami F-grupp nesovmestimosti.

A study was made of compatibility of three F-like factors of the genetic transfer (pAP22-4, pAP39, pAP41) identified in the cells of serologically typed E. coli strains with F-group incompatibility reference plasmids. The factors of pAP22-4 and pAP41 transfer are partly incompatible with groups FII, FIII, FIV, and FI, FIV, respectively, while the factors of pAP39 transfer are completely incompatible both with groups FI and FIV plasmids.