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.     

Some specific features of vaginal microflora depending on ecological factors

In 75 female residents of Vladikavkaz, aged 18-45 years, who had applied to the gynecological department with complaints of vaginal discharge, the qualitative and quantitative composition of vaginal microflora was studied. All these women were divided into 2 groups: group 1 including 38 women living in ecologically unfavorable districts of the city and group 2 including 37 women living under ecologically favorable conditions. The relationship between the ecological situation of the districts of residence and vaginal microflora in women of the reproductive age was established. Unfavorable exogenous factors were found to lead to the development of vaginal dysbacteriosis: a sharp decrease in the amount of lactoflora or its complete absence accompanied by increased amount of staphylococci, enterococci, Escherichia coli, Proteus, Klebsiella and yeast-like fungi of the genus Candida.     

Crosslinking of mRNA analog, pUUAGUAUUUAUU derivative with a photoactivated group at the guanosine residue, with human 80S ribosomes

Crosslinking of mRNA analog, dodecaribonucleotide pUUAGUAUUUAUU derivative carrying a perfluoroarylazido group at the guanine N7, was studied in model complexes with 80S ribosomes involving tRNA and in binary complex (i.e., in the absence of tRNA). It was shown that, irrespectively of complex formation conditions (13 mM Mg2+, or 4 mM Mg2+ in the presence of polyamines), the mRNA analog in binary complex with 80S ribosomes was crosslinked with sequence 1840-1849 of 18S rRNA, but in the complexes formed with participation of Phe-TPHKPhe (where the G residue carrying the arylazido group occupied position-3 to the first nucleotide of the UUU codon at the P site) the analog was crosslinked with nucleotide 1207. The presence and the nature of tRNA at the E site had no effect on the environment of position-3 of the mRNA analog. Efficient crosslinking of the mRNA analog with tRNA was observed in all studied types of complex. Modified codon GUA, when located at the E site, underwent crosslinking with both cognate valine tRNA and noncognate aspartate tRNA for which the extent of binding at the E site of 80S ribosomes was almost the same and depended little on Mg2+ concentration and the presence of polyamines.     

On the development of body-wall musculature Diplostomum chromatophorum metacercariae (Trematoda: Diplostomidae)

The body-wall musculature of invasive cercariae and metacercariae of Diplostomum chromatophorum at different intervals after the penetration into the experimental intermediate host Cyprinus carpio (1, 3, 5, 6, 7, 10, 12, 20, 34, 40 days) has been investigated with the help of TEM technique. During the first 10 days after the invasion (in conditions of our experiment), the cercarial subtegumental muscle fibres degenerate. These muscles are replaced by newly formed ones. Mass differentiation of myoblasts beneath the tegument was observed in 7-10-day-old metacercariae. Obtained data indicate the metamorphosis of body-wall musculature during the morphogenesis in Diplostomum chromatophorum metacercariae.     

Orienting reflex: "targeting reaction" and "searchlight of attention"

The concept of orienting reflex based on the principle of vector coding of cognitive and executive processes is proposed. The orienting reflex to non-signal and signal stimuli is a set of orienting reactions: motor, autonomic, neuronal, and subjective emphasizing new and significant stimuli. Two basic mechanisms can be identified within the orienting reflex: a "targeting reaction" and a "searchlight of attention". In the visual system the first one consists in a foveation of a target stimulus. The foveation is performed with participation of premotor neurons excited by saccadic command neurons of the superior colliculi. The "searchlight of attention" is based on the resonance of gamma-oscillations in the reticular thalamus selectively enhancing responses of cortical neurons (involuntary attention). The novelty signal is generated in novelty neurons of the hippocampus, which are selectively tuned to a repeatedly presented standard stimulus. The selective tuning is caused by the depression of plastic synapses representing a "neuronal model" of the standard stimulus. A mismatch of the novel stimulus with the established neuronal model gives rise to a "novelty signal" enhancing the novel input. The novelty signal inhibits current conditioned reflexes (external inhibition) contributing to redirecting the behavior. By triggering the expression of early genes the novelty signal initiates the formation of the long-term memory connected with neoneurogenesis.     

Studying plant genome variation using molecular markers

The authors' studies on the organization and variation of plant genome with the use of molecular markers are briefly reviewed with special emphasis on random amplified polymorphic DNA (RAPD), inter simple sequence repeat (ISSR), sequence characterized amplified region (SCAR), and cleaved amplified polymorphic sequence (CAPS) markers detected with the use of polymerase chain reaction (PCR). These markers have been demonstrated to be promising for identifying cultivars and determining the purity of genetic strains of pea. Genetic relationships between strains, cultivars, and mutants of pea have been studied. The role of molecular markers in molecular genetic mapping and localizing the genes of commercially important characters of pea has been shown. The possibility of the use of molecular markers for studying somaclonal variation and detecting mutagenic factors in plants during long-term spaceflights is considered. The prospects of using DNA markers for understanding the organization and variability of higher plant genomes are discussed.     

Equilibrium fluctuations in myoglobin and lysozyme

The angular dependencies of inelastic intensities of Rayleigh scattering of Moessbauer radiation were measured for myoglobin and lysozyme (in the hydration range h = 0.05-0.7). The data were fitted within the framework of model, when two types of intraglobular motions were taken into account: individual motions of small side-chain groups and cooperative motions of segments. The best agreement with the experiment at h > 0.05 was obtained when individual motions of small groups together with the cooperative motions of alpha-helices and beta-sheets for lysozyme, and alpha-helices for myoglobin were considered. At further hydration (h = 0.45), mean-square displacements (x2) of both types of motions strongly increase with the increase in hydration degree, while the motions with a large correlation radius (not less than macromolecule radius) remain nearly the same as for h = 0.05. The results of the study of the radial distribution function deduced by Fourier-transform from the diffuse x-ray measurements together with RSMR data allow one to conclude that the water during protein hydration competes with the intramolecular hydrogen bonds, loosens the protein and increases the internal dynamics. Concurrently, water arranges the ordering of macromolecule, which takes the native structure at h = 0.4-0.7. The analysis of auto and cross-correlation functions of bending fluctuations of alpha-helices in the large domain of lysozyme performed by molecular dynamics allows one to come to the final conclusion that it is the difference in the structural organization of myoglobin and lysozyme and not the presence of SS-bonds in lysozyme macromolecule that is responsible for different structural fluctuations in these proteins.