[Analysis of DNA and chromosome damage by the methods of molecular cytogenetics].

The main hybrid techniques of molecular cytogenetics are described. Methodological aspects of combination of fluorescence in situ hybridization (FISH) with the comet assay and micronuclei (MN) test are discussed along with results of their application to evaluate and locate DNA and chromosome damage in the genome. The experience of the authors with the application of FISH in combination with the comet assay and MN test are reported.

[Isolation and characterization of vaginal lactobacilli producing hydrogen peroxide].

AIM: Isolation and characteristics of vaginal lactobacilli that actively generate H2O2 and have high antagonistic activity. MATERIALS AND METHODS: Staphylococcus aureus 8956, Escherichia coli 8852, Klebsiella pneumoniae 8795 and Candida albicans 5646 were used as target-strains. Skim milk and MRS medium were used for lactobacilli isolation and cultivation. Antagonism was studied in complete agar and Saburo medium. Merckoquant peroxide test (Merck) stripes were used for the determination of H2O2. Antibacterial activity was determined by diffusion into agar. Specific culture growth rate was determined by conventional method, acidification of the culture medium--by pH-meter. RESULTS: 12 strains were isolated from vaginal smears of healthy women. These strains have an ability to ferment milk among which a highly active H2O2 producer was isolated and attributed to Lactobacillus delbrueckii by the results of 16S rRNA and alpha-subunit RNA polymerase gene sequence analysis (16S rDNA and rpoA genes are registered in GenBank, numbers HQ379171 and HQ379180 respectively). L. delbrueckii MH-10 bacterial cells were characterized by specific growth speed 1.26 per hour, reaching a maximum titer of 2 x 10(9) PFU/ml with lowering medium pH to 4.0. Under aerated conditions H2O2 concentration reached 100 microg/ml or more. L. delbrueckii MH-10 has high antibacterial activity against S. aureus, E. coli, K. pneumoniae. CONCLUSION: L. delbrueckii MH-10 isolate is an active H2O2 producer, has high growth speed and broad antibacterial activity spectrum, is a perspective candidate for the development of probiotic preparation for the prophylaxis and therapy of vaginoses.

[Genetic improvement of technological characteristics of starters for fermented milk products].

Possibility for improvement of technological characteristics of lactobacilli using mutations of resistance to rifampicin (rif(r)) and streptomycin (str(r)) was studied. Using starter model of Narine Lactobacillus acidophilus INMIA-9602 Armenian diet milk product, it was showed that a possibility for selecting strains with increased rate of milk fermentation and acid production is higher in Rif(r) and Str(r) mutants induced by nitrosoguanidine than in cultures sensitive to antibiotics. The milk products obtained using Rif(r) and Str(r) strains had high viscosity, improved texture, increased amount of alive cells and good organoleptic features.

[Effect of mechanical stress on lon mutant strain of Escherichia coli K-12]. / Vliianie mekhanicheskikh kolebanii na zhiznedeiatel'nost' lon-mutantnogo shtamma Escherichia coli K-12.

It was found that, depending on their frequency, mechanical vibrations (MVs) can either stimulate (4 Hz) or inhibit (50 Hz) the growth and the division of the lon mutant of Escherichia coli K-12. Similar effects were observed when the MV-treated nutrient medium was inoculated with untreated mutant cells. MVs enhanced the motility of mutant cells and the fragmentation of filament cells always present in the populations of lon mutants.

[DNA comet assay for evaluation of genotoxic effects in risk groups]. / Primenenue metoda DNK-komet dlia otsenki genotoksicheskikh éffektov v gruppakh riska.

DNA comet assay (CA), gel electrophoresis of single cells, is effective in evaluating the genetic (genotoxic) effects of endogenous and exogenous agents. CA was used to study the extent of spontaneous or UV-induced DNA damages in the leukocytes in two groups at genetic risk: in Chernobyl accident liquidators and patients with familial Mediterranean fever (FMF). There was a significant increase in the number of UV-induced and excision repair-mediated DNA breaks in both risk groups as compared to control samples. The spontaneous extent of DNA breaks in the cells of the liquidators and FMF patients were similar to those in the controls. The extent of oxidative DNA damages detected during incubation with the endonuclease enzymes formamidopyrimidine glycosylase and endonuclease III were also determined in FMF patients. There were no statistically significant differences in the extent of oxidative DNA damage in the cells of FMF patients as compared to the controls. The findings give grounds to recommend CA for biomonitoring of genotoxic effects.

[The effect of magnetic fields on the growth and division of the lon mutant of Escherichia coli K-12]. / Vliianie magnitnykh polei na rost i delenie lon mutanta Escherichia coli K-12.

It was shown that the static magnetic field (SMF) and electromagnetic field (EMF) caused inhibition of the cell division in Escherichia coli K-12 lon mutant. The low-frequency EMF 4 Hz led to the 20% survival, but EMF at 50 Hz increased the survival of cells up to 53%. After exposure to magnetic field cells lost capacity for division and grow as filaments, unable to form the colonies on the solid media.