PubMed Health⌕ Search

Biomedical subjects

Iu D Tsygankov

Publications and source records attributed to Iu D Tsygankov.

At least 19 recordsLinked to original sources
PubMed2005

[Bvg-negative regulation of repeated sequence transferring in Bordetella pertussis cells].

A method of monitoring the sequential events of IS481 transposition into the ctag site of bvg operon of Bordetella pertussis has been developed. Reproduction of virulent B. pertussis cells in vitro is accompanied by intrachromosomal site-specific IS481 transposition, which, in turn, results in inactivation of bvg operon of the causative agent and cell avirulent state. Avirulent bvg mutants of B. pertussis are incapable of intramolecular IS481 transposition. The frequency of the transposition increases when MgSO4 and nicotinic acid are present the culture medium. In the absence of these modulating factors. IS481 transposition along B. pertussis chromosome is inhibited but not arrested completely. Negative regulation of the bvg-repressed genes of B. pertussis seems to be a mechanism that controls bvg-dependent IS481 transposition.

Bacterial Proteins↗
PubMed1988

[Localization of prophage SM of Pseudomonas aeruginosa in the chromosome of host cells].

Pseudomonas aeruginosa PAO SM-prophage was localized on the chromosome between thr-9001 and pur-66 locuses on 42-43 min of chromosomal genetic map. The location of prophage was identified on the basis of prophage linkage with the above-mentioned markers and confirmed by the purine, hypoxanthine and threonine deletions in course of thermoinduction of SM cts6 prophage from lysogens. The decrease for two orders in lysogenization frequency of thr mutants by SM bacteriophage suggests the integration of SM prophage in these cells into some other region of chromosome.

Bacteriophages↗
PubMed1987

[Temperature-sensitive mutant of the obligate methylotroph Methylobacillus flagellatum KT deficient in glucose-6-phosphate dehydrogenase].

The common approach is developed for isolation of mutants deficient in key enzymes of ribulose monophosphate pathway for formaldehyde oxidation and assimilation by obligate methylotrophic bacteria. The approach is based on total isolation of temperature sensitive mutants and their biochemical characterization. A number of ts- mutants of obligate methylotroph M. flagellatum KT is isolated following nitrosoguanidine induced mutagenesis. The modified screening method was developed and used for identification of mutants deficient in the key enzymes of ribulose monophosphate pathway. The mutant deficient in glucose-6-phosphate dehydrogenase (zwf) was identified. The NAD-dependent activity of glucose-6-phosphate dehydrogenase was not measurable under nonpermissive temperature while the level of NADP-dependent activity was only four-fold less comparing with wild type strain. It was concluded that growth limitation of zwf mutant of M. flagellatum KT (designated T623) at 42 degrees C results from the absence of NAD-dependent activity of glucose-6-phosphate dehydrogenase.

Glucosephosphate Dehydrogenase↗
PubMed1987

[Characteristics of Methylobacillus flagellatum KT mutants, deficient for phosphoglucoisomerase, an enzyme of the ribulose monophosphate cycle of obligate methylotrophic bacteria].

The activities of the key enzymes of ribulose monophosphate cycle for formaldehyde oxidation and assimilation were tested in crude extracts from temperature sensitive mutants of obligatemethylotroph M. flagellatum KT. Two mutants deficient in phosphoglucoisomerase activity were identified during this screening. Phosphoglucoisomerase of T525 pgi-1 mutant was active both at permissive (30 degrees C) and nonpermissive (42 degrees C) temperatures. Complete inactivation of the enzyme at 42 degrees C occurred in 2 h in vitro, while in vivo incubation at nonpermissive temperature for more than 10 h was required for the enzyme inactivation. Phosphoglucoisomerase activity of T566 pgi-2 was 5-fold lower as compared with the one from the parent strain incubated at 30 degrees C. The enzyme was inactivated in 2 min. in crude extract at nonpermissive temperature.

Anemia, Hemolytic, Congenital Nonspherocytic↗
PubMed1986

[Genome organization of the plasmid of IncQ/P4 group and its vector derivatives].

The genome organization and functioning of IncQ/P4 plasmids are reviewed. Based on these plasmids, cloning vectors have been constructed for broad host range of gram-negative bacteria. Together with one- and two-replicon vectors for cloning via insertion inactivation of markers, specialized plasmid vectors are described: cosmids, promoter-probe vectors, vectors for direct selection of recombinant molecules. Examples of using broad host range vectors for gene cloning and expression in non-enteric gram-negative bacteria are presented.

Cloning, Molecular↗
PubMed1985

[Complementation and the physiological characteristics of the ts mutants of Pseudomonas aeruginosa phage SM].

Seventy three temperature-sensitive mutants of Pseudomonas aeruginosa SM phage have been obtained using different mutagens and assigned to thirteen complementation groups. Representative mutants of each group have been studied with the aim of characterizing tentatively the time of genes expression in infected bacteria. Two genes appear to function during the first minutes after infection, whereas the remaining genes are needed for late functions. Most of the temperature-sensitive functions in the different mutants are reversible, i.e. they become active when the infected cells are shifted-down to the permissive temperature.

Bacteriolysis↗
PubMed1985

[Control of lysogeny and a genetic map of the temperate phage SM of Pseudomonas aeruginosa].

76 mutants with impaired ability to lysogenize host cells were isolated in SM phage after mutagenesis using several chemical mutagens. By means of complementation test, these mutants were distributed into two groups, cI and cII. The mutants of the cI group were similar phenotypically to the cI mutants of phage lambda defective in synthesis of repressor. The mutants of the cII group establish and support the lysogenic state in infected cells with very low frequency. Temperature-sensitive mutants belonging to 13 complementation groups and nonlysogenizing mutants of the cI and cII groups were used in genetic mapping of SM phage. Mutual positions of markers and relative distances between them were determined by the method of two-factorial crosses. The greatest distance equal to 20 units of recombination was determined between ts 88 marker and one of early genes marked with ts 105 mutation. The genes cI and cII are closely linked to each other and also to ts 105 marker and are situated at one end of the genetic map.

Bacteriophages↗
PubMed1985

[Development of a system vector-host in methylotrophic bacteria].

Cloning of methylotropic and other Gram negative bacteria's genes was performed using vectors derived from IncP4 plasmids. Plasmids, such s RSF1010 are 8.8 kb in length, have a high copy number and broad host range and can be mobilized efficiently by a number of conjugative plasmids. IncP4 plasmids have relatively few restriction enzyme's targets suitable for cloning. In this paper the construction of versatile and special purpose IncP4 vectors available for cloning DNA into broad range of bacterial species are described. The seria of versatile vectors involves the transposon containing plasmid and two-replicon vectors. In genetic construction of special vector for direct cloning of restriction fragments the genetic regulation elements of Tn 1 were used. On the base of IncP4 replicon special vectors for construction of bank genes (cosmids) and the vectors for cloning of regulation sequence were also constructed.

Genetic Markers↗
PubMed1985

[The effect of R-plasmids on the reproduction of Pseudomonas aeruginosa phage SM].

The inheritance of plasmids Rms163 and R74 by Pseudomonas aeruginosa strain PAO hs been shown to effect the reproduction of a temperature bacteriophage SM. The decrease in plating efficiency of bacteriophage on Pseudomonas aeruginosa PAO (rms163) lawn is explained by the high degree of cell lysogenization by bacteriophage. Plasmid R74 inhibits bacteriophage SM propagation ultimately, evidently due to interruption of definite stages in vegetative development of bacteriophage by the products of plasmid specific genes.

Bacteriophages↗
PubMed1984

[Transducing activity of the temperate SM bacteriophage of Pseudomonas aeruginosa].

The temperate bacteriophage SM is not serologically related to the known transducing phages F116, G101, B3 of Pseudomonas aeruginosa. The strains with auxotrophic mutations within the wide ranges of the genetic map of P. aeruginosa strain PAO1 were used for studying the transducing activity of the SM phage. All of the 7 bacterial markers tested are transduced with SM phage grown on a prototrophic donor strain. The frequency of transduction of separate bacterial markers using the wild type SM phage is 2.3 to 4.6 X 10(-8). Linked ilv202+ - met28+ markers are cotransduced with SM phage at a frequency of about 1.5%.

Bacteriophages↗
PubMed1980

[Transducing phages of Pseudomonas aeruginosa related to phage F116L].

New phages K104 and B26, which are relative to F116L by a number of biological characters, appeared to show general transducing activity. Phage K104 transduces all tested markers with higher frequency than the phage B26. Linkage of the bacterial markers pair ilv202--met28 durspectively. When recipient bacteria lysogenic for phages K104 and B26 are used, frequencies of transduction by phage F116L are decreased. In the presence of F116L prophage the frequency of transduction by phage B26 is 10-fold increased. Phages B26 and F116L do not grow on bacteria lysogenic for these phages. Phage F116L does not grow on the lawn of bacteria, lysogenic for phage K104, while phage B26 grows on the same lawn with the efficiency of plating about 10(-2).

Bacteriophages↗
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↗
PubMedDate not supplied

[Isolation and general characteristics of a group of Pseudomonas aeruginosa temperate phages].

Eighteen temperate phages were isolated from 38 natural strains of Pseudomonas aeruginosa. The phages belong to five heteroimmune groups according to the ability of lysogenic variants of the strains PAO1 and PAT2 to exclude the growth of the superinfecting phage. Phages of the II and V immunity groups are serologically similar; the remaining phages are not inactivated by antisera against phages B26 (II group) and K1338 (V group). Prophages of the II, IV, and V groups are induced by UV for vegetative growth. Phages belonging to different immunity groups vary in their morphology and particle size as was found by electron microscopy. Phages of the I, II, IV and V groups comprise one morphological type, those of the III group are of another morphological type. Phages of the IV group are not adsorbed on the bacterial mutants resistant to phages of the II and V immunity groups.

Bacteriophages↗
PubMedDate not supplied

[Use of methylotrophic bacteria Methylobacillus flagellatum KT for isolation of deuterated exogenous carbohydrates].

The cultivation conditions optimal for biosynthesis of exogenous polysaccharides by methylotrophic bacteria Methylobacillus flagellatum were evaluated. The mutant strain most active in accumulating exogenous polysaccharides was selected. Gradual adaptation of this strain to the deuterated medium containing 1 vol % CD3OD in deuterium oxide intensified biosynthesis of exogenous polysaccharides and inhibited bacterial growth (compared to the standard medium). The monomeric composition of exogenous polysaccharides obtained during cultivation on standard and deuterated media was estimated by high-performance liquid chromatography and nuclear magnetic resonance spectroscopy. Nondeuterated exogenous polysaccharides contained only fructose, while deuterated exogenous polysaccharides included 98% fructose and 2% ribose. Paramagnetic resonance spectroscopy showed that the degree of deuterium incorporation into molecules of biosynthetic carbohydrates was 89%.

Adaptation, Physiological↗
PubMedDate not supplied

[The effect of amino acids in the asparagine family on the aspartate kinase and homoserine dehydrogenase of ethionine-resistant mutants of Pseudomonas putida].

The activity of aspartate kinase and homoserin dehydrogenase from ethionine resistant mutants Pseudomonas putida 25 and 6 have been studied as affected by amino acids from the family of asparagine. They are characterized by a capacity to the surplus synthesis of methionine. It is shown that mutants have negative regulation of the level of activity of the studied enzymes. It is supposed that the mutations (or mutation) could take place which affected properties of enzymes, which participated directly in the biosynthesis of methionine, in the analogue resistant clones 25 and 6.

Asparagine↗