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Biomedical subjects

N A Likhacheva

Publications and source records attributed to N A Likhacheva.

At least 19 recordsLinked to original sources
PubMed1990

[Genetic control of resistance of Escherichia coli K12 to phage C1].

The bacteriophage C1 isolated in production cycle lysis belongs to the most common group of bacteriophages wide spread in nature and having the long noncontractile motile tail. Bacterial cells sensitivity to bacteriophage C1 is determined by functioning of the three different loci mapped in different regions of Escherichia coli map at 89, 75 and 61 min. The possibility of existence of a complex receptor for bacteriophage C1 is discussed.

Bacteriophage lambda↗
PubMed1989

[Escherichia coli phage receptors. Minor porins and proteins participating in the specific transport as phage receptors].

Except for the main porin proteins OmpC and OmpF there exist the membrane proteins participating in the transport of specific substrates: phosphates, nucleosides, iron, vitamin B12, maltose and maltodextrins, that also play the role of phage receptors. Some phages use as receptors the porins determined by the genes of lambdoid prophages. LamB protein that serves receptor for phage lambda exposes the amino acids sequence on the outer surface of membranes that participates in phage adsorption. The sequence is similar to tetrapeptide of fibronectin responsible for binding with the surface of cellular receptor in eucaryotes.

Bacterial Outer Membrane Proteins↗
PubMed1989

[Phage receptors of Escherichia coli. Basic components of the outer membrane of E. coli as phage receptors].

Major outer membrane components which determine the structure and the barrier function of membrane Gram-negative bacteria are receptors for many bacteriophages. LPS--the major component of the outer membrane of Enterobacteria can be used by some phages with wide host range specificity. The other component of the outer membrane frequently include phage receptor component is OmpA protein. OmpA protein different areas can be used as receptors for different phages T--even group. A large group of phage receptors compose porin proteins, which are discovered in 32 species of bacteria. The synthesis of major porin proteins, which a receptor for several phages, are regulated by sufficiently complex system of some genes. These genes are sensitive to the changes of environment.

Bacterial Outer Membrane Proteins↗
PubMed1988

[Effect of the molecular weight of DNA on the effectiveness of plasmid transformation of E. coli K12].

The level of plasmid transformation and transfection by the high molecular mass DNA was studied for Escherichia coli mutants having increased efficiency of plasmid transformation by low molecular mass DNA. Decreased level of plasmid transformation and transfection registered in some mutants as compared to the one in wild type strain suggests the specificity of Escherichia coli cells penetration for DNA of different molecular mass.

DNA, Bacterial↗
PubMed1984

[Action of dicaine on the efficiency of plasmid transformation and transfection in Escherichia coli K12].

The action of tetracaine hydrochloride, a local anesthetic, on the effectiveness of plasmid transformation and transfection in variants of E. coli K-12 has been studied. The concentrations of tetracaine hydrochloride used in the experiment (0.002 M) affect the level of the synthesis of most proteins in the outer membrane of these bacteria. This seems to be one of the causes of changes in the effectiveness of plasmid transformation and transfection in E. coli K-12.

Anesthetics, Local↗
PubMed1983

[Escherichia coli K-12 mutants with an increased efficiency of plasmid transformation].

Escherichia coli K-12 mutants with an enhanced efficiency of plasmid transformation were obtained. In all the mutants, the efficiency of transfection with lambda vir phage DNA was changed, in comparison to the parent strain. However, these changes did not always correlate strictly with plasmid transformation alterations. For instance, two mutants with an increased plasmid transformation efficiency demonstrated 50-fold decrease in the level of transfection with lambda phage DNA. Polyacrylamide gel electrophoresis points to both quantitative and qualitative differences in protein composition of the mutant cell envelopes, as compared with the parent strain.

Bacterial Proteins↗
PubMed1983

[Comparative study of the plasmid DNA recipient capacity of Escherichia coli K-12 mutants for the main membrane proteins and of mutants with enhanced plasmid transformation efficiency].

The study of the plasmid transformation of E. coli K-12, carried out in mutants with the known damages in the main proteins of the outer membrane, made it possible to reveal the essential role of OmpA protein in this process. The damage of lipoprotein led to a considerable increase in the level of plasmid transformation. The mutants with the enhanced efficiency of plasmid transformation, obtained by the authors, were not connected with lesions in the main proteins of the outer membrane: OmpF, OmpC and OmpA.

Bacterial Outer Membrane Proteins↗
PubMed1982

[Induction of Escherichia coli K-12 mutants with an increased efficiency of plasmid transformation].

A new rapid method for plasmid transformation of Escherichia coli K-12 cells has been devised. It consists in application of plasmid pMB9 DNA to the surface of an agar medium with 0.05 M CaCl2 and tetracycline (50 micrograms/ml). The recipient cells treated with nitrosoguanidine were drifted on by sectors on the plates with pMB9 DNA. The method enabled the obtaining of 12 mutants with high efficiency of plasmid transformation.

Calcium Chloride↗
PubMed1980

[Role of Escherichia coli K-12 lambda phage receptors in transfection and plasmid transformation].

The dependence of competence of Escherichia coli cells in transfection and plasmid transformation from phage lambda receptor protein was studied. Mal+ variants, sensitive to phage lambda (Mal+ lambda S) were obtained from strains with impaired lambda-phage receptor protein (Mal-lambda R). Maximum increase of transfection (4.7-fold) was observed in JC411Mal+ lambda S strain. The efficiency of plasmid transformation of pMB9 and RP4 DNAs was also higher in the strain with functioning lambda-receptor protein.

Bacteriophage lambda↗
PubMed1979

[Transfer of a bacterial gene using phage lambda transfecting DNA].

A new amber mutation of phage with the gene coding synthesis of beta-galactosidase was received by recombination. With the help of transfection DNA isolated from this phage the transfer of the gene coding the beta-galactosidase synthesis to the recipient phage-resistant E. coli cell was realized. The suggested model can be used for the gene transfer to the recipient phage-resistant cells or other species of bacteria with transfection DNA.

Coliphages↗
PubMed1978

[Competence in Escherichia coli cells. V. Interaction of the competence factor with the cells].

Some trends of the interaction of the competence factor with the cells are described on the model of phage lambda transfection. It is shown that this process depends on the composition of the recipients growth media, the temperature regime in the interaction processand on the concentration of the competence factor and the recipient cells. The preliminary treatment of the recipient by EDTA (0.0001 M), CaCl2 (less than 0.02 M), MgCl2 (less than 0.01 M), and NaCl (less than 0.01 M) resulted in the increaze of their sensitivity to subsequent treatment by the factor. Data are obtained demonstrating that after the treatment of cells by the competence factor their sensitivity to decreased CaCl2 concentration is increasing.

Calcium Chloride↗
PubMed1976

[Competency of Escherichia coli cells. IV. Effect of freezing--thawing on the formation of competency in Escherichia coli cells in the presence of Ca++ ions].

The paper is initiated in the aim to use the effect of freezing-thawing in the system of intact Escherichia coli cells treated with Ca++ ions to increase the transfection efficiency. It is demonstrated that freezing-thawing of Ca++ treated cells increases the transfection indices of lambda phage DNA for E. coli Hfr clone with low transfection indices in 20-30 times, and for the strain of E. coli X7026 of high competence-in 5 times. Freezing-thawing efficiently increased the transfection only in cells with a decreasing competence. E. coli Hfr H cells acquired the capacity of more efficient lambda phage DNA perception independently on the growth phase, while in E. coli X7026 cells the maximal transfection increase under the effect of complementary interactions was observed at the beginning of the logariphmic and stationary growth stages, but not during the competence period. Short-term changes emerging in cells during freezing-thawing can probably promote the better penetration of Ca++ ions to active sites on the cell surface, which produces favourable conditions for lambda phage DNA formation.

Calcium↗
PubMed1975

[Competence in Escherichia coli cells. III. Formation of competent states in Escherichia coli X7026 and Escherichia coli Hfr H cells during storage in different conditions].

The competence formation in 2 strains of Escherichia coli X7026 and Hfr H to isolated phage gamma DNA after the prolonged treatment of cells with Ca++ ions at low temperatures was investigated. In both strains studied the sensitivity of cells to phage lambda DNA increased during several days of maintenance at 4 degrees C in 0.2 M CaCl2, and reached the maximal value in 24-48 hours for E. coli Hfr H cells, and in 72-96 hours for E. coli X7026 cells. Cells maintained in CaCl2 for 24 hours and more interacted more effectively with DNA in the cold, and didn't need Ca++ ions at the last stage of transfection (incubation of the infectious mixture at 37 degrees C) as the freshly grown cells did. Variations induced in the cells after the prolonged action Ca++ ions were preserved only in the presence of CaCl2. After the washing of CaCl2 from the cells with 0.15 M NaCl they returned to the initial state. The competence formation in cells of E. coli X7026 under the effect of Ca++ ions was going on more actively when the cells were preliminary incubated for several days at 4 degrees C in the absence of CaCl2. E. coli Hfr H cells were resistant to this treatment.

Calcium↗