Genetic control of the resistance to phage C1 of Escherichia coli K-12.

Escherichia coli K-12 lytic phage C1 was earlier isolated in our laboratory. Its adsorption is controlled by at least three bacterial genes: dcrA, dcrB, and btuB. Our results provide evidence that the dcrA gene located at 60 min on the E.

[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.

[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.

[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.

[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.

[Urocanic acid content of the epidermis of diabetics].

A degree of a decrease in the content of urocanic acid in washes-off from the skin surface of patients with decompensated diabetes mellitus depends on a period and gravity of disease that may be indicative of disorders of the adenylate cyclase system (or one of its links). Change in the content of urocanic acid in the epidermis of patients with diabetes mellitus treated with the Biostator apparatus, correlates with change in the content of glucagon and blood sugar. The authors discuss a possibility to use the test of urocanic acid determination for the prediction and assessment of the efficacy of therapy of patients with diabetes mellitus.

[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.

[Evaluation of the hepatotoxic activity of several chlor-nitro derivatives of benzoic acid].

Hepatotoxic effects of 4-chloro-3-nitrobenzoic acid (x-NBA), 3-nitrobenzoic acid (NBA) and 4-chlorobenzoic acid (CBA) were studied at the doses corresponding to LD50, 1/10 LD50 and 1/50 LD50. The toxic effects were estimated by monitoring alterations in activity of protein-synthesizing system in liver tissue and by the analyses for the presence in blood serum of two tissue-specific cytoplasmic enzymes of liver cells--urokaninase (EC 4.2.

[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.

[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.

[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).

[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.