Epigenetic cell reactions induced by ionizing radiation

The importance of radiation modification of epigenetic activity in the general mechanism of radiobiological reactions is proved. The inheritable epigenetic changes induced by irradiation are one of the basic reasons of formation of the remote radiation pathology. It is noted that epigenetic inheritable changes of cells have the determined character distinguishing them from mutation changes, being individual and not directed. It is underlined the ability of ionizing radiation to modify a level of spontaneous genetic instability inherited in a number of cell generations on the epigenetic mechanism.     

A new electrometric approach to studying specific biomolecular complexes

In the article the results of the influence of some types of biological molecules and their specific immune complexes on the volt-amperic characteristics of surface-barrier contact structures with the super thick metal film are presented. Moreover, the possibility to develop on this basis a simple instrumental method for separate registration of initial components and products of their interaction is discussed. It was shown that the volt-amperic characteristics of surface-barrier structures of Ni-Si changed at the deposition of myoglobin and its specific monoclonal antibodies. These structures more essentially reacted to the formed presence of specific immune complex and, in particular, to the direct formation of this complex on the surface at the subsequent use of the initial immune components in comparison with their separate presence. For all investigated types of biological molecules and their specific complexes we found optimal thickness of metal film when changes of volt-amperic characteristics of system achieved maximum level. It was concluded that this electrometrical method was suitable for the express and separation free registration of specific immune complex.     

Luminescence of aqueous solutions of glycine and its N-methyl derivatives

A nonmonotonous dependence of luminescence intensity of aqueous solutions of 0.1 M glycine and its N-methyl derivatives on the number of methyl groups in the solute molecule was found. A correlation between luminescence intensities and optical density at the excitation wavelength of 300 nm was revealed. Possible causes of the phenomenon observed were analyzed. Among these are: luminescence of admixtures, intrinsic luminescence of dissolved molecules, and luminescence related to the formation of nanoscale complexes in solution. On the basis of the data, it is impossible to make a final choice between the three above-mentioned mechanisms of luminescence of aqueous solutions of glycine and its N-methyl derivatives.     

The experience of FISH technique application for reconstruction of individual radiation doses in Chernobyl liquidators in the framework of Ukrainian-American project "Leukemia"

The results of proper investigations received under the cytogenetic examination of 225 persons (control groups, Chernobyl liquidators exposed to different radiation doses, oncogematology patients) had been summarized and analyzed. The conclusion concerning possibilities and limitations of FISH technique usage for retrospective biodosimetry of human radiation exposure has been presented.     

An oligonucleotide primer system for amplification of the ribulose-1,5-bisphosphate carboxylase/oxygenase genes of bacteria of various taxonomic groups

Based on the analysis of GenBank nucleotide sequences of the cbbL and cbbM genes, coding for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPC), the key enzyme of the Calvin cycle, a primer system was designed that allows about 800-bp-long fragments of these genes to be PCR-ampliflied in various photo- and chemotrophic bacteria. The efficiency of the designed primer system in detection of RuBPC genes was demonstrated in PCR with DNA of taxonomically diverse bacteria possessing RuBPC genes with a known primary structure. Nucleotide sequences of RuBPC gene fragments of bacteria belonging to the genera Acidithiobacillus. Ectothiorhodospira, Magnetospirillum, Methylocapsa, Thioalkalispira, Rhodobacter, and Rhodospirillum were determined to be deposited with GenBank and to be translated into amino acid sequences and subjected to phylogenetic analysis.     

Copper-catalyzed cleavage of DNA by arenes

DNA was found to be cleaved in neutral solutions containing arenes and copper (II) salts. The reaction is comparable in efficiency with the DNA cleavage by such systems as Cu(II)-phenanthroline and Cu(II)-ascorbic acid, but, in contrast to the latter, the system Cu(2+)-arene does not require the presence of an exogenous reducing agent or hydrogen peroxide. The system Cu(2+)-arene does not cleave DNA under anaerobic conditions. Catalase, sodium azide, and bathocuproine, which is a specific chelator of Cu(I), completely inhibit the reaction. The data obtained allow one to suppose that Cu(I) ions, superoxide radical, and singlet oxygen participate in the reaction. It has been shown by the EPR method using spin traps that the reaction proceeds with formation of alkoxyl radicals, which can insert breaks in the DNA molecule. For effective cleavage of DNA in the Cu(II)-o-bromobenzoic acid system, the radicals have to be generated by a specific copper-DNA-o-bromobenzoic acid complex, in which copper ions are most probably coordinated with oxygen atoms of the DNA phosphate groups. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2003, vol. 29, no. 6; see also http://www.maik.ru.     

Study of alpha-satellite DNA in cosmid libraries, specific for chromosomes 13, 21, and 22, using fluorescence in situ hybridization

Fluorescent in situ hybridization (FISH) was employed in mapping the alpha-satellite DNA that was revealed in the cosmid libraries specific for human chromosomes 13, 21, and 22. In total, 131 clones were revealed. They contained various elements of centromeric alphoid DNA sequences of acrocentric chromosomes, including those located close to SINEs, LINEs, and classical satellite sequences. The heterochromatin of acrocentric chromosomes was shown to contain two different groups of alphoid sequences: (1) those immediately adjacent to the centromeric regions (alpha 13-1, alpha 21-1, and alpha 22-1 loci) and (2) those located in the short arm of acrocentric chromosomes (alpha 13-2, alpha 21-2, and alpha 22-2 loci). Alphoid DNA sequences from the alpha 13-2, alpha 21-2, and alpha 22-2 loci are apparently not involved in the formation of centromeres and are absent from mitotically stable marker chromosomes with a deleted short arm. Robertsonian translocations t(13q; 21q) and t(14q; 22q), and chromosome 21p-. The heterochromatic regions of chromosomes 13, 21, and 22 were also shown to contain relatively chromosome-specific repetitive sequences of various alphoid DNA families, whose numerous copies occur in other chromosomes. Pools of centromeric alphoid cosmids can be of use in further studies of the structural and functional properties of heterochromatic DNA and the identification of centromeric sequences. Moreover, these clones can be employed in high-resolution mapping and in sequencing the heterochromatic regions of the human genome. The detailed FISH analysis of numerous alphoid cosmid clones allowed the identification of several new, highly specific DNA probes of molecular cytogenetic studies--in particular, the interphase and metaphase analyses of chromosomes 2, 9, 11, 14, 15, 16, 18, 20, 21-13, 22-14, and X.     

Quantitative isolation of microbial DNA from the different types of soils of natural and agricultural ecosystems

A novel procedure was developed for direct quantitative isolation of microbial DNA from soil. This technique was used to evaluate microbial DNA pools in soils of contrasting types (chernozems and brown forest soils) under different anthropogenic loads. A strong correlation was found between microbial biomass and DNA contents in soils of different types (R2 = 0.799). The ratio of soil CO2 emission rate to the amount of extractable DNA in the soil was shown to reflect physiological state of the soil microbial community; this ratio can be used as an ecophysiological parameter similarly to the metabolic quotient qCO2.     

Influence of neurotensin on behavior of rats with lesions in serotonergic neurons

After serotonergic lesion by administration of 5,7-dihydroxytryptamine into the dorsalis raphe nucleus, effects of neurotensin microinjections into the caudate nucleus and substantia nigra on rat behavior were compared. Serotonergic lesions resulted in motivated excitement of rats manifested as an increase in the number of intersignal motor reactions during realization and, particularly, extinction of thirst conditioned reflex. Neurotensin microinjections into the caudate nucleus facilitated extinction of the conditioned reflex both in operated and control rats, but such microinjection into the substantia nigra facilitated this process only in operated animals. Neurotensin did not change conditioned reflex realization in both groups of animals but decreased emotional excitement of rats in the "open field". The behavioral effects of neurotensin in operated rats are connected with normalization of motivational and emotional states of animals and may be explained by recovery of interaction between the dopamine- and serotonergic systems. It is suggested that the mechanisms of this normalizing effects of neurotensin at the levels of the caudate nucleus and substantia nigra are different and are associated preferentially with its action either on dopamine- or serotonergic structures.     

The role of antioxidant systems in the response of Escherichia coli to acetamidophenol and some antibiotics

The role of glutathione and other antioxidant systems in the response of Escherichia coli to acetamidophenol (paracetamol), rifampicin, and chloramphenicol was studied. The exposure of aerobically growing E. coli cells to acetamidophenol diminished the intracellular level of glutathione by 40% and the reduced-to-oxidized glutathione ratio in the cells by 50%, while it enhanced the expression of the antioxidant genes soxS and sodA by 2.7 and 1.8 times, respectively. Glutathione-deficient cells were more susceptible to acetamidophenol than were normal cells. All this suggests that acetamidophenol induces a mild oxidative stress in E. coli cells. The oxidative stress induced by rifampicin was still less pronounced, whereas chloramphenicol-treated E.coli cells exhibited no signs of oxidative stress at all.