[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]. / Rol' khromosomnogo Thr-Leu-segmenta E. coli K-12 v ékspressii fin V-sistemy ingibirovaniia perenosa F-podobnoi plazmidy 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]. / Mutatsii geneticheskoi oblasti Fin F-podobnoi plazmidy 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+.

[Genetic region of incompatibility of the F-like plasmid pAP-18-1]. / Geneticheskaia oblast' nesovmestimosti F-podobnoi plazmidy pAP18-1.

With help of molecular cloning the genetic region controlling incompatibility of plasmid pAP18-1 (Inc FXI) was localized in EcoR1-fragment f5 (3.6 MD). The genetic region of incompatibility of its derepressed mutant pAP18-1drd (Inc FVII) is situated in EcoR1-fragment f2 (7,2 MD).

[Genetic organization of transfer region of F-like plasmid pAP18-1]. / O geneticheskoi organizatsii oblasti perenosa F-podobnoi plazmidy pAP18-1.

The results of complementation analysis of nitrosoguanidine-induced mutants of F-like drd-plasmid pAP18-1 (Tc, ColV) testified to the existence of at least 3 tra regions (tra1, tra2, tra3) and regulating locus fin V in the genome of this plasmid. By means of molecular cloning of tra2 region and locus fin V of plasmid pAP18-1drd were located in Sall-fragment f5 (3.9 MD).

[Molecular genetic study of the changes in the incompatibility and regulation of the transfer of the F-like pAP18-1 plasmid induced by nitrosoguanidine and the Tn5 and Tn9 transposons]. / Molekuliarno-geneticheskoe izuchenie izmenenii nesovmestimosti i reguliatsii perenosa F-podobnoi plazmidy pAP18-1, indutsirovannykh nitrozoguanidinom i transpozonami Tn5 i Tn9.

Relation between induced mutations of plasmid pAP18-1 (Tc, Col) and alterations in it's restriction map was studied. Nitrosoguanidine induced mutations of transfer regulation system and incompatibility of this plasmid related with alteration in the situation of recognition sites for restrictases EcoR1 and Sal1 in map positions 42.2-4.3 and 12.9-17.9 MD. Insertions of transposons Tn5 and Tn9 into the plasmid DNA resulted in a decrease of incompatibility level.

[Complementation analysis of derepressed mutants of F-like plasmids of Escherichia coli]. / Komplementatsionnyi analiz derepressirovannykh mutantov F-podobnykh plazmid Escherichia coli.

Complementation analysis of a number of conjugative transfer functions was performed in derepressed (drd) mutants of E. coli F-like plasmids. The major part of double plasmid complexes investigated has revealed the formation of complementation transfer inhibitor of Fin V-type, or less frequently--the formation of Fin U-type inhibitor. An additional complementation analysis of drd plasmids defective at Fin V region genes has demonstrated at least three genes (denoted A, B, C) in the structure of this region.

[Effect of transposons on the system regulating derepressed plasmid tra-genes]. / Vliianie trasnpozonov na sistemy reguliatsii tra-genov derepressirovannykh plazmid.

The ability of standard plasmids of six Fin-groups to inhibit the functions of genes transferring derepressed F-like plasmids has been studied. It is shown that transposons incorporation into the structure of individual plasmids alters the regulatory system of plasmid tra-genes.

[Characteristics of the derepressed mutant of the F-like plasmid pAP18-1 coding for tetracycline resistance in Escherichia coli]. / Kharakteristika derepressirovannogo mutanta F-podobnoi plazmidy pAP18-1, kodiruiushchei rezistentnost' k tetratsiklinu u Escherichia coli.

A transfer function derepressed mutant of the F-like plasmid pAP18-1 (Tc, ColV) was induced with the help of N-methyl-N'-nitro-N-nitrozoguanidine. The mutant plasmid pAP18-1drd belongs to the FVII incompatibility group of the F-like plasmids. The plasmid pAP18-1drd is characterized by the loss of the capacity for inhibiting the tra-genes functions of the Flac plasmid and is sensitive to the Tra-function inhibitors of the reference plasmids of the FinV and FinW groups.

[Systems regulating the tra genes of derepressed F-like plasmids]. / Izuchenie sistem reguliatsii tra-genov derepressirovannykh F-podobnykh plazmid.

A study was made of the ability of reference plasmids of the 6 known Fin-groups to inhibit the functions of transfer genes (tra-genes) of the 4 derepressed F-like plasmids (pAP22-2, pAP38, pAP43, pAP53). It was shown that unlike the derepressed Flac plasmid, the conjugation transfer of pAP38 and pAP53 plasmids was inhibited only by, the FinV plasmid, whereas pAP22-2 plasmids by Fin V and Fin V plasmids. The formation of donor-specific pili in case of pAP38 plasmid was inhibited by Fin Q, Fin U and Fin V plasmids, in case of pAP43 plasmid by Fin U Fin V and Fin W plasmids.

[Effect of transposons Tn1 and Tn9 on the genetic regulation system of transfer and incompatibility functions of Col-plasmid pAP19-1]. / O vliianii transpozonov Tn1 i Tn9 na sistemu geneticheskoi reguliatsii funktsii perenosa i nesovmestimost' Col-plazmidy pAP19-1.

F-like pAP19-1 Col-plasmid was labeled with transposons Tn1 and Tn9 and transfer functions of its derepressed mutants were investigated. The plasmid indicated was compatible with reference plasmids of 9 F-like incompatibility groups. Thus it belongs to the new incompatibility group FX. The ability of Tn9 to change the incompatibility of the plasmid investigated was discovered.

[Conjugativity and incompatibility of derepressed pAP11-2 plasmid]. / Kon"iugativnost' i nesovmestimost' derepressirovannoi plazmidy pAP11-2.

It has been demonstrated during investigation of Colplasmid pAP11-2 and its varieties labeled with transpozone (Tn1 and Tn9) that this plasmid is a derepressed one in terms of transfer functions in E. coli strain K-12 cells as well as in some of serologically typed strains of this type. The plasmid under study is incompatible with reference plasmids belonging to two different groups (FI and FIV) and is marked by a number of the properties common to the system of genetic control over Tra-functions.

[Genetic characteristics of plasmid pAP53 derepressed in transfer functions detected in the cells of an opportunistic E. coli strain]. / Geneticheskie osobennosti derepressirovannoi po funktsiiam perenosa plazmidy pAP53, vyiavlennoi v kletkakh uslovno-patogennogo shtamma E. coli.

A study was made of plasmid pAP53 derepressed as regards transfer functions (Tra-functions) detected in E. coli strain cells, serogroup 0128, after its labeling with transpozones Tn1 and Tn9. The compatibility tests demonstrated that the plasmid belongs to the incompatibility group FIII and is partially incompatible with the group FII reference-plasmid. Plasmid pAP53 is unable to inhibit Tra-functions of plasmid F'lac and is not inhibited by the fin type genetic regulation on the OP group plasmids under study. At the same time Tra-functions of plasmid pAP53 are inhibited in the presence of pAP41 plasmid, which indicates that this plasmid has a special type of genetic regulation.

[Genetic features of the F-like pAP10-2 plasmid controlling synthesis of thermostable enterotoxin in E. coli cells]. / Geneticheskie osobennosti F-podobnoi plazmidy pAP10-2, kontroliruiushchei sintez termostabil'nogo énterotoksina v kletkakh E. coli.

A study was made of the genetic traits of F-like plasmid pAP10-2 that monitors the synthesis of thermostable enterotoxin after plasmid labelling with Tn9 transpozone. It has been shown that the test Ent-plasmid is a conjugative one, suppresses fertility functions of F plasmid and belongs to the F1 incompatibility group.