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Biomedical subjects

V N Krylov

Publications and source records attributed to V N Krylov.

At least 109 records · Page 6Linked to original sources
PubMed1977

[Discovery of a new type of restriction and modification in a group of intestinal bacteria].

The adsorption of 23 new lambdoid bacteriophages to 547 strains which isolated from natural population of Enterobacteriaceae was studied. The frequency of positive combinations of phage-bacterium with adsorption is not more than 2%. A study of possible causes of limited growth of lambdoid phages in the bacterial strains revealed that neither homoimmune prophage nor prophage P2 are single factors of the growth limitation. It is found that in natural populations a selection of bacterial strains with the least limitation of phage takes place. Three cases of killing bacteria after infection with high multiplicity are found. The reason of the killing effect is manifestation of some functions by infecting phages. A new restriction-modification system is found which differs from restriction-modification system A, B, K, 15, P1, EcoRI, EcoRII. The most of strains, which adsorb phages but do not support their growth, are supposed to possess several mechanisms of restriction. Thus, the search of new restriction system in Escherichia coli is worthwhile.

Adsorption↗
PubMed1977

[Site-specific recombination between phages lambda and phi 81 and integration of hybrid phages lambda-phi 81].

Dependence of the formation frequency of hybrid phages immlambdahphi81 and immphi81hlambda in recombination between phages lambda and phi81 from int-function of both phages is studied. Phages with hybrid att-sites (Plambda OP'phi81 and Pphi81OP'lambda) are isolated and the efficiency of integration of these phages into bacterial chromosome is determined.

Chromosomes, Bacterial↗
PubMed1977

[Isolation and study of int-mutants of pi81 bacteriophage].

Int mutants of the lambdoid bacteriophage pi81 were isolated. With mapping of deletion the location of Int gene on the genetic map of prophage pi81 was was determined. Complementation of int function of prophages lambda and pi81 was demonstrated in the formation of stable lysogenics.

Coliphages↗
PubMed1976

[Genetic study of bacteriophage phi81. I. Isolation, study of complementation and preliminary mapping of amber-mutants of bacteriophage phi81].

123 Amber mutants of lambdoid bacteriophage phi81 are isolated and distributed into 19 complementation groups. Deletion mapping made possible to locate 5 gene groups on the genetic map of bacteriophage phi81 and to determine a region of possible location of mm' sticky ends on the prophage genetic map. A gene of phage phi81 is localized, which controls the adsorption specificity, and which functional similarity to a respective gene of phage phi80 is demonstrated.

Chromosome Mapping↗
PubMed1976

[New lambdoid Escherichia coli phages. I. Isolation, group immunity and recombination with lambda phage].

550 bacterial strains were isolated from sewage. 69 of them were lysogenic by phages active on Escherichia coli. The phages were divided into two groups on the basis of UV-inducibility, the ability to form plaques on Rep-E. coli mutants and particle morphology: lambdoid (23 phages) and related to P2 (46 phages). Hybrid phages isolated from the crosses of lambdoid phages with phage lambda harboured the region imm lambda and the gene of adsorption specificity from other parent. Ten groups of heteroimmune phages were found in the collection of new temperate phages are homoimmune with known phages: lambda, phi 80, phi 81, 434. Another 7 phages involved in 6 groups of immunity which were heteroimmune to known phages. Diversity of lambdoid phage genes determining the structure of repressor is discussed.

Coliphages↗
PubMed1976

[New lambdoid phages of Escherichia coli. II. Comparison of several genetic characteristics with lambda phages].

Functions of some newly isolated lambdoid phages and phage lambda genes were compared by their ability to interact with unrelated phages and the product of the bacterial gene gro P. 19 of 23 lambdoid phages studied interfere with prophage P2, that points out the presence of functionally active genes, essential for spi+ phenotype in their genomes. The development of 4 lambdoid phages with spi- phenotype is independent on the prophage P2 presence. Most of lambdoid phages show the reduced growth ability on the C600 groP- bacterial lawn. This indicates that they have a function similar to the gene P of phage lambda. The development of phage phi M417 in bacterial mutants groP- is not disturbed, which indicates that the gene P of phage phi M417 is different from that of the phage lambda. Newly isolated phages, that are homoimmune to phage lambda, restrict the development of T4 rII phage. The rest lambdoid phages have no rex function. The growth efficiency of lampodid phages on E. coli C cells, carrying Eco R1 plasmid, varies from 10(-6) to 10(-8) that presumbaly indicates on different amounts of restionci strites in DNA of these phages.

Coliphages↗
PubMed1976

[Detection of the products of several T4B phage genes among the proteins of infected Escherichia].

Proteins of wild-type phate T4 and its mutants in genes rII, su(30), stII, stIII, rVI-39 and 60 are studied by means of polyacrylamide gel electrophoresis in the presence of sodium dodecylsulphate of membrane fractions and lysates of infected bacteria. Physiological studies of mutants in these genes carried out by the authors and other investigators allow to suggest that when functions are realized, the products of these genes interact with the plasmatic membrane of the infected bacteria. The product of rIIB cystrone has been indentified as the protein of the membrane of an infected bacterium, its molecular weight being about 30 000. The products of genes su(30), stII, stIII and rVI could not be identified either in lysate or in membrane fraction. The function of gene stII is "superstoichiometric", which may be due to the involvement of a very small product amount when the function of gene stII is realized. Mutants in genes 39 and 60 lack one and the same protein with molecular weight of about 40 000 which is a protein of the membrane of an infected bacterium. This protein may be a product of gene 39, and the functional product of gene 60 is necessary to synthesize it.

Bacterial Proteins↗
PubMed1975

Mutations in the new gene stIII of bacteriophage T4B suppressing the lysis defect of gene stII and a gene e mutant.

Mutations of bacteriophage T4B were found which suppress the lysis defect of both gene stII mutants and gene e mutants. The suppressor mutations belong to a new gene, stIII, of phage T4B. Gene stIII is located on the genetic map of T4B between genes stI and e. stIII mutants sometimes form star plaques on Escherichia coli B. The latent period on E. coli 594, but not E. coli B, is shorter with stIII mutants than that with wild-type phage. The premature lysis of E. coli 594 infected with stIII phage does not depend on the expression of both stII+ and e+ function. StIII allele is dominant over the stIII+ with respect to both the ability to suppress the stII defect and the early lysis of infected E. coli 594 cultures.

Alleles↗
PubMed1975

[A genetic and physiologic study of mutations of T4 phage suppressing the lysis defect of gene stII mutants].

A new gene rVI phage T4B is found. Mutations rVI belong to the class of r-mutations of T4B. Mutations rVI do not show the lysis inhibition after superinfection and determine the r-morphology of plaques on Escherichia coli CR63 lawn. Mutations rVI are gene-specific suppressors of stII lysis defect, but do not suppress the e lysis defect. Alleles rVI and rVI+ are co-dominated with regard to the ability to suppress the stII lysis defect. The suggest the stoichiometric character of rVI gene function. Mutations rVI increase the permeability of infected cells before the lysis. The gene rVI located between the genes 56 and 39 on the T4B genetic map, close to the gene 56. The still mutations described earlier (Krylov, Yankovsky, 1973) suppress the lysis defect of the am z25 mutant in the gene e. The suppression is manifested when infected bacteria develope only in the liquid media.

Cell Membrane Permeability↗