[Gamma-radiation action on cells of algae Euglena gracilis].

Considering the potentials of algae Euglena to constitute a part of biological systems of human life support, effects of low radiation doses on algal cells and radiosensitivity dependence on their genotype were studied. In experiments with gamma-irradiation (60Co) of Euglena gracilis, the highest radioresistance was demonstrated by strain Z. OFL; the chloroplasts lacking Z-derived strain showed hypersensitivity to radiation. E. bacillaris and derived chlorophyll-lacking strains W3 and W10 had intermediate radiosensitivity. Irradiation with the doses of up to 10 Gy produced a hormetic effect in the stock strains. Cells death was observed only after irradiation by doses above 100 Gy. The stimulating effect was exerted both on radioresistance and growth rate. Dyes made possible rapid evaluation of the proportion of living and dead cells. Comparison of two survival tests showed that the classic medium inoculation overestimates cell deaths as it disregards the living non-proliferating cells.

[Participation of SRM5/CDC28, SRM8/NET1, and SRM12/HFI1 genes in checkpoint control in yeast Saccharomyces cerevisiae].

About twenty genes participating in checkpoint control are known in yeast Saccharomyces cerevisiae. The involvement of SRM genes in the cell cycle arrest under the action of injurious agents was studied in this work. These genes were earlier defined as genes affecting genetic stability and radiosensitivity. It was shown that mutations srm5/cdc28-srm, srm8/net1-srm, and srm12/hfi1-srm shorten the cell cycle arrest in the presence of DNA damage and influence the checkpoint arrest in G0/S (srm5, srm8), G1/S (srm5, srm8, srm12), S (srm5, srm12), and G2/M (srm5). It seems likely that genes SRM5/CDC28, SRM12/HFI1/ADA1, and SRM8/NET1 are involved in the formation of a cell response to DNA damage, and in checkpoint regulation in particular.

[Activation of repair and checkpoint control by double-strand DNA breaks: a cascade of activational protein phosphorylation].

Molecular mechanisms of activation of DNA repair and checkpoint control by double-strand breaks are considered. They include phosphorylation by protein kinases of repair and checkpoint proteins resulting in their activation, alteration of affinity to other proteins, and alteration of their localization.

[Simulation of kinase CDK2-cyclin A by the molecular dynamics method: effect of Gly16-->Ser16 and Arg274-->Gln274 substitutions on conformation of a kinase subunit].

The nanosecond-long molecular dynamics of the movement of the active protein kinase CDK2/ATP complex has been analyzed. The simulations of substitutions CDK2-G16S in the conserved G-loop of a small lobe and CDK2-R274Q in a large lobe showed the importance of the amino acid residues in the conformation of kinase and their effect on the conformation of CDK2, which shows up in an increase in the distance between G- and T-loops in the corresponding mutant forms. The results obtained indicate that the induction of both Gly16-->Ser16 and Arg274-->Gln274 mutations destabilize the local structure of kinase around the T-loop area. The mutation Arg274-->Gln274 has a more pronounced effect and results in a loosening of the structure of kinase and an increase of the distance between G- and T-loops.

[Interaction between checkpoint genes RAD9, RAD17, RAD24, and RAD53 involved in the determination of yeast Saccharomyces cerevisiae sensitivity to ionizing radiation].

Mechanisms for genetic control of cell division cycle (checkpoint control) have been studied in most detail in yeast Saccharomyces cerevisiae. To clarify the role of checkpoint genes RAD9, RAD17, RAD24, and RAD53 in cell radioresistance, double mutants were analyzed for cell sensitivity to ionizing radiation. Double mutants carrying mutations in combination with mutation rad9Delta were shown to manifest the epistatic type of interaction. Our results suggest that checkpoint genes RAD9, RAD17, RAD24, and RAD53 belong to a single epistatic group designated RAD9 and govern the same pathway. Genes RAD9 and RAD53 have a positive effect on sensitivity to gamma-radiation, whereas RAD17 and RAD24 have a negative effect. Interactions between mutations may differ when considering their sensitivity to gamma-radiation and UV light; mutations rad9Delta and rad24Delta were shown to manifest the additive effect in the first case and epistatic effect in the second.

[Interaction between checkpoint genes RAD9, RAD17, RAD24, and RAD53 involved in the determination of yeast Saccharomyces cerevisiae sensitivity to ionizing radiation].

Mechanisms for genetic control of cell division cycle (checkpoint control) have been studied in most detail in yeast Saccharomyces cerevisiae. To clarify the role of checkpoint genes RAD9, RAD17, RAD24, and RAD53 in cell radioresistance, double mutants were analyzed for cell sensitivity to ionizing radiation. Double mutants carrying mutations in combination with mutation rad9delta were shown to manifest the epistatic type of interaction. Our results suggest that checkpoint genes RAD9, RAD17, RAD24, and RAD53 belong to a single epistatic group designated RAD9 and govern the same pathway. Genes RAD9 and RAD53 have a positive effect on sensitivity to gamma-radiation, whereas RAD17 and RAD24 have a negative effect. Interactions between mutations may differ when considering their sensitivity to gamma-radiation and UV light; mutations rad9delta and rad24delta were shown to manifest the additive effect in the first case and epistatic effect in the second.

[Molecular dynamics modeling of the substitution of serine for the conservative glycine in the G loop in the yeast cdc28-srm mutant using the crystalline lattice of human kinase CDK2].

Two-nanosecond molecular dynamics modeling of the crystalline lattice of an active complex of kinase pT160-CDK2/cyclin A/ATP-Mg2+ substrate has been performed. The results of modeling indicated that the structures of the nonmutant CDK2 complex and mutant CDK2 complex, which involves the G 16S-CD K2 substitution corresponding to that of yeast, markedly differ, the differences in structural conformations being particularly well pronounced in those regions that play a key role in the functioning of kinase. Based on the results of computations, structural elements are considered that may affect the kinase activity and regulatory phosphorylation, and the binding of protein kinase to cyclins and substrates.

[New mutation in Saccharomyces cerevisiae SRM genes and some features of their phenotypic effects]. / Novye mutatsii genov SRM Saccharomyces cerevisiae i nekotorye osobennosti ikh fenotipicheskogo proiavleniia.

The effects of the previously identified mutations in nuclear genes SRM8, SRM12, SRM15, and SRM17 on the maintenance of chromosomes and recombinant plasmids in Saccharomyces cerevisiae cells and on cell sensitivity to ionizing radiation were studied. The srm8 mutation caused instability of chromosome maintenance in diploid cells. In yeast cells with the intact mitochondrial genome, all examined srm mutations decreased the mitotic stability of a centromeric recombinant plasmid with the chromosomal ARS element. Mutations srm12, srm15, and srm17 also decreased the mitotic stability of a centromereless plasmid containing the same ARS element, whereas the srm8 mutation did not markedly affect the maintenance of this plasmid. Mutations srm8, srm12, and srm17 were shown to increase cell sensitivity to gamma-ray irradiation. The SRM8 gene was mapped, cloned, and found to correspond to the open reading frame YJLO76w in chromosome X.

[Radiosensitivity of Saccharomyces yeasts and srm genes: effects of srm1 and srm5 mutations]. / Radiochuvstvitel'nost' drozhzhei sakharomitsetov i geny srm: éffekty mutatsii srm1 i srm5.

The presence in the cell genotype of srm1 and srm5 (cdc28-srm) mutations decreasing the spontaneous rho- mutability was shown to have no effect on the rates of spontaneous nuclear gene mutations and gamma-ray-induced mitotic recombination. Mutation cdc28-srm exerts a marked effect on cell sensitivity to the lethal action of ionizing radiation and on the appearance of homoplasmic segregants generated from heteroplasmic diploids. Additive interactions between mutations cdc28-srm and each of the rad6 and rad52 mutations were revealed by an analysis of double mutants with respect to their sensitivity to radiation. Mutation rad9 was epistatic with mutation cdc28-srm. These data agree with the idea that the p34CDC28 gene product is a target for the RAD9-dependent feedback control operating at the cell cycle checkpoints (checkpoint control) and ensuring an additional amount of time for premitotic repair of chromosomal DNA damage.

[Regularities of the induction of point mutation in the yeast Saccharomyces cerevisiae after exposure to gamma-radiation]. / Zakonomernosti induktsii tochkivykh mutatsii u drozhzhei Saccharomyces cerevisiae pri gamma-oblychenii.

A tester system consisting of six isogenic strains was used to study the regularities of the induction of point mutations in the yeast Saccharomyces cerevisiae after exposure to gamma-radiation. This system allowed the identification of all six possible substitutions in the Cys-22 codon of the CYC1 gene encoding iso-1-cytochrome c. The dose dependence of the frequency of these six base-pair substitutions was shown to be linear-quadratic. The pattern of base substitutions did not depend on the doses of gamma-irradiation used (from 125 to 1000 Gy) and predominantly included GC-->AT transitions and AT-->TA transversions. The possible mechanisms of gamma-ray mutagenesis leading to a nonlinear dose dependence were considered, and the spectra of mutations obtained for different yeast genes and for Escherichia coli were compared.

[Analysis of maintenance of redundant genetic structures in the yeast Saccharomyces cerevisiae: effect of mutations cdc28-srm and srm1]. / Analiz podderzhaniia izbytochnykh geneticheskikh struktur u drozhzhei Saccharomyces cerevisiae: éffekty mutatsii cdc28-srm i srm1.

The effects of nuclear gene mutations cdc28-srm and srm1 on the maintenance of various recombinant facultative genetic structures (FGSs) in Saccharomyces cerevisiae were studied. These structures are ARS1 TRP1 mini-coils, noncentromeric circular plasmids containing various ARS elements, and extended linear yeast artificial chromosomes (YAC). These mutations led to an increase in the mitotic stability of some of the FGS tested and the disturbed maintenance of the others. Mutation srm1 imposed a stabilizing effect on the maintenance of various recombinant FGSs with ARS chromosomal elements. Mutation cdc28-srm destabilized the maintenance of only those recombinant FGS that shared full or detectable homology with sequences of the nuclear genome of the yeast cell.

[Isolation and characterization of new nuclear srm gene mutation causing coordinated changes in the maintenance of nuclear and mitochondrial genetic structures in the yeast Saccharomyces]. / Poluchenie i kharakteristiki novykh iadernykh gennykh mutatsii srm, vyzyvaiushchikh koordinirovannye izmeneniia podderzhaniia iadernykh i mitokhondrial'nykh geneticheskikh struktur u drozhzhei sakharomitsetov.

From grown cultures of UV-irradiated Saccharomyces cerevisiae cells with disomy at chromosome IV, clones with nuclear gene mutations were isolated, each of which was suggested to change both mitochondrial spontaneous rho- mutability and the mitotic stability of extra natural chromosomes. Four such nonallelic mutations (srm8, srm12, srm15, and srm17) were isolated, and their phenotypic expression characterized. All four mutations are associated with decreased spontaneous rho- mutability and virtually block sporulation in homozygous mutant diploids. Mutation srm8 is temperature-sensitive and, most probably, involves an essential gene. Double mutants of genotypes srm8 cdc28-srm and srm8 srm12 are nonviable. Mutation srm12 increases the rate of spontaneous loss of extra chromosome XIV by disomics by a factor of about 30. Mutation srm15 induces a small (about twofold) but statistically significant decrease of this rate. Mutations srm8 and srm17 drastically decelerate reproduction of cells with disomy, which prevents quantitative estimations of rates of loss of extra chromosomes.

[A behavioral and biochemical analysis of the therapeutic effect of sodium oxybutyrate in alcoholic encephalopathy in progeny]. / Povedencheskii i biokhimicheskii analiz terapevticheskogo éffekta natriia oksibutirata pri alkogol'noi éntsefalopatii u potomstva.

The alcoholization of pregnant female rats (5 g/kg) results in a decrease of endogenous ethanol level in their offspring and distant disturbances of the conditioned reflex activities of the young rats deteriorating the formation and preservation of the skill with an emotional positive reinforcement. Sodium gamma-gydroxybutyrate administered in a dose of 50 mg/kg from the 8th to the 20th day of life prevents the above-mentioned disturbances of learning and memory, restores the level of endogenous ethanol, corrects the parameters of lipid and mediator metabolism in the brain and blood changed by prenatal alcoholization.

[Repair of a double-stranded gap in plasmid DNA in radiosensitive mutants of Saccharomyces cerevisiae: effectiveness and precision]. / Reparatsiia dvunitevykh breshei plazmidnoi DNK u radiochuvstvitel'nykh mutantov Saccharomyces cerevisiae: éffektivnost' i tochnost'.

The repair of a double strand gap in plasmid DNA in radiosensitive mutants of Saccharomyces cerevisiae has been studied. The proportion of repair events resulting in the complete doublestrand gap recovery of the plasmid DNA has been found to be close to 100% in Rad+ cells. The mutation rad55 did not interfere in the doublestrand gap repair efficiency and accuracy. The mutant rad57 is capable of the effective doublestrand gap repair without restoration of the DNA sequence deleted by the gap. The mutation rad53 substantially inhibited the efficiency of the doublestrand gap repair but did not influence the accuracy of the repair. Plasmid DNA doublestranded gap repair is completely blocked by mutations rad50 and rad54.

[Effects of sodium oxybutyrate on the level of catecholamines and serotonin and monoamine oxidase activity in patients with alcoholism]. / Vliianie natriia oksibutirata na urovni katekholaminov, serotonina i aktivnost' monoaminoksidazy u bol'nykh alkogolizmom.

Sodium salt of gamma-hydroxybutyric acid (Na-GHB) was administered to 37 drug-free alcoholic men in placebo controlled study. The psychotropic effect was evaluated using psychometric scale of 4 ranges. Changes in plasma levels of epinephrine, norepinephrine, dopamine, serotonin and platelet MAO-B activity were assessed. The psychotropic effect was observed in 27 (76%) patients. The baseline of dopamine concentration was significantly correlated with the expression of psychotropic effect. Na-GHB decreased dopamine concentration in responders. The possible involvement of dopaminergic system in the realization of psychotropic effect of Na-GHB was discussed.

[Various biochemical indicators in prenatally alcoholized rats]. / Nekotorye biokhimicheskie pokazateli u krys pri antenatal'noi alkogolizatsii.

A number of biochemical parameters have been determined which characterized the state of CNS and the structure of cell membranes in antenatally alcoholized animals. As compared with the control group the alcoholized animals had a significantly increased level of phosphatidyl inositol diphosphate in brain phospholipid fractions, while content of serotonin was reduced in their brain and increased in blood plasma; content of phosphatidyl serine and the cholesterol/phospholipids ratio were reduced in brain.