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Biomedical subjects

S Cebrat

Publications and source records attributed to S Cebrat.

32 records · Page 2Linked to original sources

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate. IV. Reconstruction in R404 plasmid aggregate and separation of twelve genetically distinct derivative forms.

R404 plasmid aggregate is composed of two conjugative and two nonconjugative plasmids. Plasmid aggregate reconstructed from separated plasmids had the same genetic properties as the original R404 plasmid aggregate. It was found that plasmids of R404 factor could be transferred in conjugation in twelve different sets. These twelve genetically distinct classes of transconjugants formed only six groups differing in phenotypic characters.

Conjugation, Genetic↗

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate. II. Separation of plasmids by transformation.

Transformational separation of plasmids from R404 plasmid aggregate found in Salmonella enteritidis strain was performed. Three classes of transformants differing in their resistance patterns were isolated. Genetic properties of the transformants suggest that their resistance is determined by single plasmids. Plasmid pCK3 (Tra-ApCbCrSuSm) and pCK4 (Tra-ApCbCrCm) are nonconjugative while plasmid pCG1 (TraApCbCrSuSmTcKmNm) is conjugative. Separation of all plasmids of R404 plasmid aggregate allowed to determine their genetic properties and the manner of conjugational transfer of R404 plasmid aggregate R-determinants.

Anti-Bacterial Agents↗

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate. III. Entry exclusion features of its separative forms.

The genetic relationship of four plasmids separated from R404 plasmid aggregate has been characterized by investigating entry exclusion and intracellular incompatibility. It has been found that the four plasmids exist in an autonomous state in cells carrying the aggregate. They are compatible and the two conjugative plasmids possess different traS genes.

Anti-Bacterial Agents↗

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate I. Conjugational separation of different derivative plasmid aggregates and their genetic properties.

Conjugational transfer of R404 factor, found in Salmonella enteritidis strain, was examined. Six derivative forms differing in resistance pattern were isolated. The manner of conjugational separation during transfer of R404 factor from E. coli to E. coli strain was the same as from the original strain of S. enteritidis to E. coli strain. During following conjugation, all isolated forms except one, could give forms differing in a resistance pattern from the parenteral ones. This one form, from which different conjugational forms could not be separated, was assumed to be a single plasmid and was designated pCK2. All other forms, including the original R404 factor were assumed to be plasmid aggregates.

Conjugation, Genetic↗

Transformation of Escherichia coli by R404 factor DNA and properties of the transformants.

Three r-determinants (Cb Cm Cf) out of eight present in R404 factor were transferred in transformation of Escherichia coli by the plasmid DNA isolated from minicells. The r-determinants acquired in this way formed the replicon tr404-1 and were untransferable by conjugation unless another self-transmissible plasmid was present in recipient. The evidences are presented in support of hypothesis that the transfer events consist in infection of transformant cells with sex factor, recombination between tr404-1 replicon and the sex factor and finally transfer of the new formed structure to the host cells of the sex factor.

Anti-Bacterial Agents↗