PubMed Health⌕ Search

Biomedical subjects

A M Lysenko

Publications and source records attributed to A M Lysenko.

At least 37 records · Page 2Linked to original sources
PubMed1984

[DNA homology study of Corynebacterium diphtheriae v. gravis groups I, II and III, Corynebacterium ulcerans and Corynebacterium pseudotuberculosis (ovis)].

The homology of genomes within Krylova 's groups I, II and III of C. diphtheriae, including toxigenic C. diphtheriae and their nontoxigenic precursors within the same group, was confirmed by the method of DNA/DNA molecular hybridization; the homology of DNA within the groups was 89-103%, the thermostability of heteroduplexes being high (on the level of homoduplexes ). The heterogeneity of genomes within these 3 groups of cultivar gravis was confirmed, which made it possible to consider C. diphtheriae, groups I, II and III, to belong to different, though closely related species; in intergroup hybridization the homology of DNA varied, as a rule, between 66% and 73%, while the thermostability of heteroduplexes was low: delta T50 was -3 degrees C to -6 degrees C. The differences in genomes (on the level of different species) between 3 groups of C. diptheriae v. gravis on one hand and C. diphtheriae v. mitis C7 (-) tox- and its convertant C7 (beta) tox+ of phage tox+ on the other hand (DNA homology being 56-62%), as well as between C. diphtheriae v. intermedius No. 328 tox+ on one hand and the representatives of 3 groups of C. diphtheriae v. gravis and C. diphtheriae v. mitis, strain C7 (beta) tox+, on the other hand (DNA homology being 42-43%) were revealed. The heterogeneity of genomes (on the level of different genera) was revealed between C. diphtheriae strains, cultivars gravis (groups I, II and III), mitis (C7(-) tox- and C7 (beta) tox+) and intermedius (No. 328 tox+) on one hand and C. ulcerans and C. pseudotuberculosis (ovis) strains on the other hand; DNA homology was 11-17% for C. ulcerans and 22-26% for C. pseudotuberculosis (ovis), the thermostability of heteroduplexes being at the lowest level (delta T50 was -11 degrees C to -13 degrees C). As a result, C. diphtheriae, classified by Bergey as a single species, was found to comprise 5 species detected by means of marking in accordance with their phenotypical features and genome structure, carried out by the method of DNA/DNA molecular hybridization; among these species were group I, II and III strains of cultivar gravis, strain C7 of cultivar mitis and strain No. 328 of cultivar intermedius. C. ulcerans and C. pseudotuberculosis (ovis) strains investigated in this study can possibly be placed outside the genus including 5 C. diphtheriae species.

Base Sequence↗
PubMed1984

[Comparison of the physicochemical structure of DNA in Corynebacterium related to C. diphtheriae v. mitis, intermedius and gravis].

The hybridization of DNA of 19 C. diphtheriae v. mitis strains with DNA of 3H-labeled C. diphtheriae v. mitis strain C7(beta) tox+ resulted in revealing four homology levels: I (102-98%), II (78-68%), III (61-50%) and IV (42-25%). Homology levels I and II differed from one another on the level of species. In the hybridization of DNA of the same strains with DNA of 3H-labeled C. diphtheriae v. gravis (group II) strain 165(1) tox+ three homology levels were revealed; levels I and II differed from one another on the level of the genus. In the first and second series of the experiments the distribution of DNA of the above strains on these levels not always coincided. The genomes of C. diphtheriae v. mitis strains 7111 tox+ and 132 tox+ were shown to differ from those of both reference strains on the level of the genus. In strains C7(beta) tox+ and PW-8 tox+ Massachusetts the genetic similarity of their genomes on the level of species was disclosed. Among C. diphtheriae v. mitis and intermedius strains at least 5 homology levels were revealed; this fact suggests the presence of at least 5 bacterial species among them. The relationship of strains on the level of species within groups I and II of C. diphtheriae v. gravis was confirmed: DNA of the related strains belonging to the corresponding group were always to be found within the same homology level. Also confirmed was the fact that the strains of groups I and II, as well as strain C7(beta) tox+, differed on the level of species.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1983

[Phenotypic expression of plasmid pPL7065 in Bacillus pumilus in free and integrated states].

There are about 20 copies of pPL7065 plasmid in cells of Bacillus pumilus ATCC7065 with molecular weight of 4.7 X 10(6) daltons. A spontaneous purine dependent mutant LK1 was isolated which contained no autonomous plasmid. However, the presence of the plasmid in LK1 cells was proved by DNA - DNA hybridization. To accomplish this, hybrid plasmid p1G1 was constructed by cloning pPL7065 on a vector pBR322 and multiplying it in Escherichia coli C600. The plasmid then was hybridized with chromosomal DNA of Bac. pumilus LK1. A pur+ revertant has been obtained from LK1 containing autonomous plasmid pPL7065, similar to the parental strain ATCC7065. These results are indicative of pPL7065 integrated into the chromosome of LK1. Bacteria having the autonomous plasmid are oligosporogeneous and produce specific antibiotics. Integration of the plasmid into bacteria causes pur phenotype, normal sporulation and a change in antibiotic synthesis and resistance. LK3 strain which lost pPL7065, sporulates normally and produces the antibiotic that inhibits growth of Bac. pumilus ATCC7065.

Anti-Bacterial Agents↗
PubMed1982

[Nucleotide composition and homology of the DNA of parasitic Leptospira].

The study of DNA in parasitic leptospirae of different serovariants by the method of molecular hybridization has revealed two groups differing in their homology level. The homology of nucleic acids has been found to correlate with serological properties. The serovariants ensuring cross immunity are characterized by the high level of homology of their DNA.

Cross Reactions↗
PubMed1981

[Changes in Bacillus pumilus antibiotic activity and sensitivity with integration and disintegration of plasmid pPL 7065].

The role of plasmid pPL 7065 in the control of the antibiotic production and sensitivity in Bac. pumilus was studied with the use a plasmid-free strain and strains containing the plasmid in the cells in a free or chromosome-integrated state. It was found that all the strains had antibiotic activity only with respect to a limited number of gram-positive bacteria. Still, the antibiotics produced by them differed in the antibacterial spectrum. The antibiotic produced by the plasmid-free strain had a broader spectrum. It was shown that the bacteria with the plasmid in th free state were sensitive to the antibiotics produced by the plasmid-free strain for the strain or the strain with the chromosome-integrated plasmid. It was suggested that plasmid pPL 7065 played the role of a modifier of the antibiotic activity and sensitivity in Bac. pumilus and carried no genetic information for the control of the antibiotic synthesis. Their formation is determined by the chromosome genes.

Anti-Bacterial Agents↗
PubMed1980

[Integrative suppression of antibiotic formation in Bacillus pumilus].

Relationship between antibiotic production and pPL 7065 plasmid integration into the chromosome of B. pumilus ATCC 7065-K was studied. With this purpose hybridization of plasmid DNA isolated from strain ATCC 7065 producing no antibiotic was performed with chromosome DNA of B. pumilus ATCC 7065 and W20, as well as B. subtilis and E. coli K-12. Plasmid DNA labeled with 3H was used in the experiments. It was found to be slightly bound with DNA of B. subtilis (0.8 per cent), E. coli K-12 (0.2 per cent), and B. pumilus W20 (3 per cent). Still, its hybridization with chromosome DNA of B. pumilus ATCC 7065-K was effective (11 per cent). It is concluded to be due to hybridization between plasmid pPL 7065 of strain ATCC 7065 and the same plasmid but integrated into the chromosome of the antibiotic-producing strain ATCC 7065-K. Therefore, derepression of the antibiotic biosynthesis is a sequence of integrative suppression.

Anti-Bacterial Agents↗
PubMed1978

[High-yield isolation of chloroplast DNA from Hordeum vulcare barley protoplasts].

A fraction of intact chloroplasts free of other cell components in isolated from barley leaf chloroplasts. Instead of mechanical desintegration of plant tissue, the method described includes the cellulysine treatment, thus increasing the yeild of chloroplast DNA. The mean content of DNA per barley chloroplast is found to be 1.10(-4) g. Base composition of barley chloroplast DNA is 39.8 mol.% of G+C. The treatment of chloroplast DNA with restriction endonuclease EcoRI results in the appearance of 17-19 bands under agarose gel electrophoresis.

Cellulose↗
PubMed1977

[Mutagenic process in bacteriophage T4B after long-term exposure to a mutagen].

Bacteriophage T4B was continuously passed on solid media in the presence of 5-bromodeoxyuridine in two simultaneous experiments. The subsitutions of amino acids were registered, and in one of the experiments biological changes were revealed in non-optimal conditions. Calculations has shown that the number of amino acid substitutions observed corresponds to at least 140--200 fixed mutations. The possibility of the mutation fixation via selection is discussed and their relative neutrality is suggested.

Amino Acids↗
PubMed1976

[Frequency distribution of pyrimidine isopliths in the DNA of actinophage F448 and Actinomyces coelicolor 66].

Base composition distribution of pyrimidine isopliths with general formula PyrnPn+1 in DNA of Actinomyces coelicolor 66 Kras. and in DNK of its actinophage F448 were investigater. These DNAs differ both pyrimidine isoplith distribution and in composition. The quality of shorter pyrimidine tracts in Actinomyces coelicolor DNA is higher compared with that in actinophage F448 DNA. The possibility of exogenic origin of actinophage F448 is discussed.

Bacteriophages↗
PubMedDate not supplied

[Comparative study of the homology of DNA in thermophilic and mesophilic lactococcal strains of various origin].

A comparative study of DNA homology among 12 strains of thermophilic streptococci currently used as ferments in the dairy industry in different regions of the CIS and 16 strains of mesophilic lactococci obtained from different sources was performed by the method of optical reassociation in solution. These strains were found to form three groups with DNA homology generally not exceeding 30-35% between each other. These data indicate that strains commonly classified as Streptococcus thermophilus may belong to different taxa. At the same time, the DNA base composition was similar in all these strains (the G + C content was 38-40 mol %). Among 16 strains of mesophilic lactococci DNA homology was generally higher than 50%, i.e., all these strains indeed belong to the same species, Lactococcus lactis.

DNA, Bacterial↗
PubMedDate not supplied

[Physiological and phylogenetic diversity of thermophilic spore-forming hydrocarbon-oxidizing bacteria from oil fields].

The distribution and population density of aerobic hydrocarbon-oxidizing bacteria in the high-temperature oil fields of Western Siberia, Kazakhstan, and China were studied. Seven strains of aerobic thermophilic spore-forming bacteria were isolated from the oil fields and studied by microbiological and molecular biological methods. Based on the 16S rRNA gene sequences, phenotypic characteristics, and the results of DNA-DNA hybridization, the taxonomic affiliation of the isolates was tentatively established. The strains were assigned to the first and fifth subgroups of the genus Bacillus on the phylogenetic branch of the gram-positive bacteria. Strains B and 421 were classified as B. licheniformis. Strains X and U, located between B. stearothermophilus and B. thermocatenulatus on the phylogenetic tree, and strains K, Sam, and 34, related but not identical to B. thermodenitrificans and B. thermoleovorans, undoubtedly represent two new species. Phylogenetically and metabolically related representatives of thermophilic bacilli were found to occur in geographically distant oil fields.

Bacillus↗