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1.
The influence of elevated temperatures (38-41 degrees C) on chromosomes of human lymphocytes on different phases of the cell cycle was studied. A high thermosensitivity of chromosomes was demonstrated during (S + G2)-phases of the cell cycle. There was a significant increase in the number of aberrant cells at t greater than 38.5%. The main types of chromosome aberrations were chromatid and chromosome deletions. Cells with 3-5 aberrations and induction of chromosome aberrations due to breaks in the centromere region were noticed at high temperatures (40-41 degrees). 相似文献
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Radiosensitivity of Chinese hamster cells increased by 1.71 times in the presence of arabinoside cytosine and hydroxyurea after gamma-irradiation, and no sensitization occurred after irradiation with carbon ions of 6.6 MeV/nuclon (LET, 227 keV/micron). Under a standard set of conditions, the RBE coefficient of carbon ions decreased from 3.09 to 1.78 in the presence of DNA synthesis inhibitors. The possible mechanism of this phenomenon is discussed. 相似文献
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Role of mutations in parC and gyrA in forming resistance of Mycoplasma hominis to fluoroquinolones 总被引:1,自引:0,他引:1
Gushchin AE Ladygina VG Govorun VM 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1999,(4):19-24
The set of the laboratory strain M. hominis H-34 mutants resistant to fluoroquinolones (ciprofloxacin-Cfl, lomefloxacin-Lfl, ofloxacin-Ofl) was obtained by selection in broth medium. The mutation was found in the quinolone resistance-determining region (QRDR) of A subunit of topoisomerase IV gene (parC) and new mutations were found in QRDR of genes encoding the A subunit of DNA gyrase (gyrA) in M. hominis mutants resistant to various concentrations of the Cfl, Lfl and Ofl. After multistep selection of the obtained mutants at constant concentrations of Cfl additional mutation Ser83 to Trp was revealed. No mutations in parE and gyrB were found. Mutations in parC for laboratory strain M. hominis H34 appeared at lower antibiotic concentrations than in gyrA. All mutations in gyr A were associated with mutations in parC. This confirms the previous data that topoisomerase IV is the primary target of Cfl and Ofl and suggests that it is the primary target of Lfl. Some M. hominis mutants selected at Ofl without any substitution in QRDRs were shown to be insensitive to Cfl and of Lfl. Studies of cross-resistance of the selected M. hominis mutants showed that their resistance to various fluoroquinolone concentrations could not depend on any mutations in QRDR of topoisomerase IV and DNA gyrase genes and suggests involvement of other unknown molecular mechanisms specific for Mycoplasmas. 相似文献
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Archakov AI Govorun VM Dubanov AV Ivanov YD Veselovsky AV Lewi P Janssen P 《Proteomics》2003,3(4):380-391
Protein-protein interactions play a central role in numerous processes in the cell and are one of the main fields of functional proteomics. This review highlights the methods of bioinformatics and functional proteomics of protein-protein interaction investigation. The structures and properties of contact surfaces, forces involved in protein-protein interactions, kinetic and thermodynamic parameters of these reactions were considered. The properties of protein contact surfaces depend on their functions. The contact surfaces of permanent complexes resemble domain contacts or the protein core and it is reasonable to consider such complex formation as a continuation of protein folding. Characteristics of contact surfaces of temporary protein complexes share some similarities with active sites of enzymes. The contact surfaces of the temporary protein complexes have unique structure and properties and they are more conservative in comparison with active site of enzymes. So they represent prospective targets for a new generation of drugs. During the last decade, numerous investigations were undertaken to find or design small molecules that block protein dimerization or protein(peptide)-receptor interaction, or, on the contrary, to induce protein dimerization. 相似文献
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Taganov KD Gushchin AE Abramycheva NIu Govorun VM 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》2000,(2):30-33
Nucleotide sequence of Acholeplasma laidlawii genome site PG-8B (1000 n.p.), containing topoisomerase IV subunit genes (parE and parC), has been determined. Sequenced genome site contains a gene fragment coding for the C-terminal region of ParE and gene fragment coding for N-terminal region of ParC. Topoisomerase IV subunite genes in A. laidlawii genome are situated near each other and overlapping by 4 nucleotides. Selection in liquid nutrient medium with ascending antibiotic concentrations resulted in derivation of A. laidlawii PG-8B cells resistant to ciprofloxacin, a fluoroquinolone. The resistant clones contain a mutation in the parC QRDR region determining fluoroquinolone resistance: Ser(91) (corresponding to Ser(80) in Escherichia coli ParC) replacement) for Leu. 相似文献
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Demina IA Serebryakova MV Ladygina VG Rogova MA Kondratov IG Renteeva AN Govorun VM 《Biochemistry. Biokhimii?a》2010,75(10):1252-1257
The goal of this work was to create a model for the long persistence of Mycoplasma gallisepticum in depleted medium and under low growth temperature followed by proteomic study of the model. Nanoforms and revertants for
M. gallisepticum were obtained. Proteomic maps were produced for different stages of the formation of nanoforms and revertants. It is shown
that proteins responsible for essential cellular processes of glycolysis, translation elongation, and DnaK chaperone involved
in the stabilization of newly synthesized proteins are crucial for the reversion of M. gallisepticum to a vegetative form. Based on the current data, it is assumed that changes in the metabolism of M. gallisepticum during nanoforming are not post-mortal, thus M. gallisepticum does not transform to uncultivable form, but remains in a reversible dormant state during prolonged unfavorable conditions. 相似文献
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Ikryannikova LN Afanas'ev MV Akopian TA Il'ina EN Kuz'min AV Larionova EE Smirnova TG Chernousova LN Govorun VM 《Journal of microbiological methods》2007,70(3):395-405
A MALDI TOF MS based minisequencing method has been developed and applied for the analysis of rifampin (RIF)- and isoniazid (INH)-resistant M. tuberculosis strains. Eight genetic markers of RIF resistance-nucleotide polymorphisms located in RRDR of rpoB gene, and three of INH resistance including codon 315 of katG gene and − 8 and − 15 positions of the promoter region of fabG1-inhA operon were worked out. Based on the analysis of 100 M. tuberculosis strains collected from the Moscow region in 1997–2005 we deduced that 91% of RIF-resistant and 94% of INH-resistant strains can be identified using the technique suggested. The approach is rapid, reliable and allows to reveal the drug resistance of M. tuberculosis strains within 12 h after sample isolation. 相似文献
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A2144G is the main mutation in the 23S rRNA gene of Helicobacter pylori associated with clarithromycin resistance 总被引:2,自引:0,他引:2
Momynaliev KT Selezneva OV Kozlova AA Vereshchagin VA Il'ina EN Govorun VM 《Genetika》2005,41(10):1338-1344
To detect point mutations A2115C, A2143G/C, and A2143G in the 23S rRNA gene of Helicobacter pylori associated with resistance of the microorganism to clarithromycin, a new powerful way of analysis was used. This method involved the reaction of minisequencing followed by MALDI-TOF mass spectrometry of reaction products. In ten analyzed clarithromycin-resistant clinical isolates of H. pylori obtained in Russia, the resistance was found to be mediated only by mutation A2144G in the 23S rRNA gene. 相似文献