Deuterium Oxide Enhances Escherichia coli SOS Response Induced by Genotoxicants.

It has been demonstrated that deuterium oxide enhances the SOS response of Escherichia coli cells induced by chemical genotoxicants and mutagens. This demonstrates that the heavy nonradioactive hydrogen isotope deuterium can be considered to be a comutagen.

[Genotoxic effects of pesticide fipronil in somatic and generative cells of mice].

The pronounced genotoxic effect of fipronil in all used doses (4.75, 9.50, 19.00, and 31.70 mg/kg) at a single exposure in the liver, lungs and spleen was ascertained by the Comet assay. Organ specificity of genotoxic effects of the pesticide was revealed. The liver was the most sensitive to fipronil. Fipronil at a dose of 9.50 mg/kg in a single and repeated exposure (within 10 days) induced aberrations in mouse bone marrow cells with the frequency exceeding the spontaneous mutation rate (p < 0.01 and p < 0.001, respectively). Fipronil also showed genotoxic activity in the germ cells of the experimental animals, causing abnormalities of the structure of synaptonemal complexes in the spermatocytes.

[IMMUNOCYTOCHEMICAL ANALYSIS OF THE DISTURBANCES IN THE STRUCTURE OF SYNAPTONEMAL COMPLEXES IN SPERMATOCYTE NUCLEI IN MICE UNDER EXPOSURE TO ROCKET FUEL COMPONENT].

There was performed an assessment of genotoxic effects of rocket fuel component--unsymmetrical dimethylhydrazine (UDMH, heptyl)--on forming germ cells of male mice. Immunocytochemically there was studied the structure of meiotic nuclei at different times after the intraperitoneal administration of UDMH to male mice. There were revealed following types of disturbances of the structure of synaptonemal complexes (SCs) of meiotic chromosomes: single and multiple fragments of SCs associations of autosomes with a sex bivalent, atypical structure of the SCs with a frequency higher than the reference level. In addition, there were found the premature desinapsis of sex bivalents, the disorder offormation of the genital corpuscle and ring SCs. Established disorders in SCs of spermatocytes, analyzed at 38th day after the 10-days intoxication of animal by the component of rocket fuel, attest to the risk of permanent persistence of chromosomal abnormalities occurring in the pool of stem cells.

[Elastogenesis-Related Gene Polymorphisms and the Risk of Pelvic Organ Prolapse Development].

Pelvic organ prolapse (POP) represents a urologic and gynecological disease, the development of which is governed both by environmental and genetic factors. We describe the results of our association study of polymorphic variants of genes involved in the assembly of elastic fibrils, namely, the lysyl oxidase protein 1 (LOXL1) and fibulin-3 (FBLN3) genes. We revealed an association of the rs2304719-T allele and rs2165241 (C)-rs2304719(T)-rs893821(T) haplotype of the LOXL1 gene with an increased risk of POP development, as well as a weak association with the disease of the rs3791660-C allele and the rs3791679(T)- rs1367228(A)-rs3791660(C)-rs2033316(A) haplotype of the FBLN3 gene.

[Genetic toxicology: findings and challenges].

The review highlights the history of genetic toxicology as a distinct research area, as well as the issues of genetic toxicology and development of its methodology. The strategies and testing patterns of genotoxic compounds are discussed with the purpose of identifying potential human carcinogens, as well as compounds capable of inducing heritable mutations in humans. The main achievements of genetic toxicology in the 20th century are summarized and the challenges of the 21st century are discussed.

[Distribution of genes of toxin-antitoxin systems of mazEF and relBE families in bifidobacteria from human intestinal microbiota].

The in silico analysis of 36 sequenced genomes of bacteria of the Bifidobacterium genus determined the presence of 19 genes of toxin-antitoxin (TA) systems that belong to the MazEF and RelBE families, including five mazF and two relE genes that encode toxins and 12 relB genes that encode antitoxins. A high level ofgene (at the level of nucleotide changes) and genomic (presence or absence of genes in distinct genomes) polymorphism in the investigated genes was revealed. The highest level of polymorphism was observed in strains of the Bifidobacterium longum species, primarily in relB1-10 genes. Gene and genomic polymorphism might be used to identify the strain of B. longum species. PCR analysis ofgenomic DNA of 30 bifidobacteria strains belonging to the three species, B. longum, B. adolscentis, and B. bifidum, isolated from the intestinal microbiota of astronauts demonstrated the presence of mazF and relB genes. The observed polymorphism of TA genes indicates the presence of differences in bifidobacteria strains isolated from the intestinal microbiota of astronauts before and after space flight and the control group.

[Damage to synaptonemal complex structure and peculiarities of selection of mouse spermatocytes I at response to drug administration].

Using immunocytochemistry methods, the structure of synaptonemal complexes (SC) of chromosomes in spread nuclei of primary spermatocytes of mice at 1, 10, and 36 days after the 10-day intraperitoneal administration of antibacterial preparations of three pharmacological groups: furacilin, an antiseptic derivative of nitrofuran; cifran, an antibiotic from the group of fluoroquinolones; and sextaphage, a polyvalent piobacteriophage was investigated. The maximal number of disturbances in the structure and behavior of synaptonemal complex was revealed on the first day after the end of preparation administration. On days 10 and 36, the total number of disturbances in SC structure decreased gradually. On the first day after the end of the administration of cifran and sextaphage in 41.8 and 25% of nuclei, respectively, the fragmentation of synaptonemal complexes was revealed and, in males to whom furacilin had been administered, the fragmentation of synaptonemal complexes was identified in 100% of nuclei. Multiple chromosome fragmentation is a meiotic disaster and results in the degeneration of cells without enabling the mechanism ofpachytene arrest. The features of pachytene arrest were revealed in the nuclei of primary spermatocytes with the disturbances of chromosomes pairing. After the administration of sextaphage, circle structures released from the lateral elements of SC and are dyed with antibodies to SCP3 protein.

[Organ specificity of the genotoxic effects of cyclophosphane and dioxidine: an alkaline comet assay study].

The applicability of alkaline comet assay to studying the organ specificity of the genotoxic effects of drugs has been estimated using cells from four organs of mice (the liver, lungs, spleen, and brain). It has been found that cyclophosphamide damages DNA in all the four organs; and dioxidine, in all organs except the brain. It is concluded that this method can be used for studying the organ specificity of the DNA-damaging effects of various substances.

[Candidate gene association study of the radiosensitivity of human chromosomes with candidate gene polymorphisms upon exposure to gamma-irradiation in vitro and in vitro].

The genotypic associations of the frequencies of spontaneous and radiation-induced chromosome aberrations in human lymphocytes were studied to develop genetic tests for elevated and reduced radiosensitivity. Cytogenetic analysis and genotyping (19 sites of detoxification and DNA repair genes) were carried out for a sample of Chernobyl cleanup workers (n = 83) and for a homogenous control sample of volunteers (n = 99). In both groups, the frequency of chromosome-type aberrations proved to be elevated in carriers of minor alleles in the XPD gene (sites T2251G (Lys751Gln) and G862A (Asp312Asn)) and a combination of GSTM1-GSTT1-positive genotypes. The polymorphism of these gene did not affect the frequency of gamma-radiation-induced aberrations in the controls (1 Gy in vitro), which was associated with the alleles of the OGG1, XRCC1, and CYP1A1 genes. Thus, the frequencies of spontaneous and in vitro induced chromosome-type aberrations are associated with the alleles of different xenobiotic detoxification and DNA repair genes. At the same time, among the cleanup workers (irradiated in vivo), the elevated frequency of aberrations was observed in the carriers of the genotypes associated with the higher rate of spontaneous (but not induced in vitro) cytogenetic damages in the controls.

[Variability in the frequency of TCR-mutant lymphocytes associated with gene polymorphisms in women living in radiation-polluted areas].

The paper presents the results of an association study of a predisposition to increased somatic mutagenesis detected by the test for TCR-mutant lymphocytes (CD3-CD4+ phenotype). A study group consisted of 251 women who lived in the towns polluted by radionuclides after the Chernobyl accident and had estrogen-dependent reproductive system diseases (uterine myoma, fibrocystic mastopathy). The carriage of minor alleles in the genes (CYP1A1, GSTM1, and ABCB1) of all three stages of detoxification of xenobiotics was associated with the rise in the spontaneous frequency of TCR-mutant cells. Overweight modified the genotype (at CYP1A1 and GSTT1 loci) - environment interaction. When background radiation became higher, the contribution of minor alleles in the CYP1A1 genes to the instability recorded as the elevated frequency of TCR-mutant cells increased.

[Complex study of the mutagenic effect of soil pollutions with petrochemical products in the Chechen Republic].

A study to evaluate congenital morphogenetic variants (CMGVs) and the association of the polymorphism of the xenobiotic detoxification and repair genes with cytogenetic parameters was conducted for the first time in children living in different climatic zones and areas polluted with primary petroleum refining products. Analysis of CMGVs and cytogenetic parameters in children points to the total genotoxic impact of oil pollutions. The children's higher sensitivity to environmental pollution is associated with the polymorphism of the detoxification gene, with the base excision repair gene XRCC1 in particular.

[Polymorphism of repair genes and cytogenetic radiation effects].

For 99 healthy volunteers, the frequencies of spontaneous and y-induced (1 Gy in vitro) chromosome aberrations in blood lymphocytes were compared with the results of PCR-genotyping by 8 repair genes: XRCC1, XPD, ERCC1, APEXI, RAD23B, OGG1, ATM, Tp53 (in all, 10 polymorphic sites). The frequency of spontaneous aberrations of chromosome type increased additively with the number of copies of minor allele of excision repair gene XPD variant *2251G and *862A D (p = 0.025). The frequency of gamma-induced chromosome aberrations proved to be elevated for the carriers of a minor allele OGG1*977G (p = 0.011). The significantly elevated number of gamma-induced chromosome aberrations was also observed for the carriers of major alleles XRCC1*G1996 and XRCC1*C589 (p = 0.002).

[The relationship between genotypes and frequencies of chromosome aberrations in human lymphocytes under irradiation in vivo and in vitro].

The data on the variability of an elevated level of the frequencies of chromosome aberrations for a group of liquidators of the Chernobyl Nuclear Station accident depending on genotypes by candidate loci are presented. The genotyping was carried out by sites, which previously showed the associations with the cytogenetic variability in control experiments. It was shown that, for a group of liquidators heterozygote by site SOD2 C47T, the control level of the frequency of chromosome aberrations is not exceeded significantly. At the tendency level, the frequency of aberrations for liquidators was reduced for double homozygotes by deletions of genes GSTM1-GSTT1 and for homozygotes by the minor allele of site CYP1A1 T606G that is in an accordance with the results of experiments with the control sampling. The elevated level of chromosome aberrations for liquidators, as a whole, is observed for genotypes, which are characteristic of an elevated level of spontaneous aberrations, and it does not completely correspond to genotypes with the elevated radiosensitivity of chromosomes.

[Somatic mutagenesis in human lymphocytes depending on genotypes for detoxification and oxidative response loci].

Associations of polymorphism of seven detoxification genes and three genes of oxidative response with the frequency of chromosome aberrations in human peripheral blood lymphocytes were studied. The genotyping data were correlated with the frequencies of spontaneous and gamma-induced (1 Gy in vitro) chromosome aberrations estimated for a group of healthy donors (97 males under 25 years of age) by analyzing 500-1000 metaphase cells per individual. The spontaneous level of aberrations of the chromosomal type was reduced in homozygotes for the GSTM1 locus deletion, and especially in double homozygotes for deletions of the GSTM1 and GSTT1 genes. The frequency of gamma-induced chromosome aberrations was reduced in G/G homozygotes for the minor allele of the poorly studied CYP1A1 T606G site: 0.094 +/- 0.006 against 0.112 +/- 0.002 for T allele carriers (P = 0.004). Linkage of the T606G site with well known and functionally important sites of the CYP1A1 gene (A4889G, T3801C) was analyzed.

[Efficiency of the prediction of carcinogenic activities of chemical substances based on scoring somatic mutations in the soybean Glycine max (L.) Merrill].

The efficiency of scoring somatic mutations in soybean (Glycine max (L.) Merrill) leaves as a test for carcinogenic activity of chemical substances in rodents has been evaluated. The efficiency of the test used alone or as part of a battery of tests has been estimated. The mutagenic activities of some chemical substances estimated using the soybean test are presented. Selective information on the carcinogenic activities of substances obtained in special carcinogenicity tests has been used as a quantitative measure of the efficiency of the tests with soybean leaves. To estimate the weight of evidence for the presence of this activity in the tested substances, a special function has been used whose values are uniquely related to the complete information, which is the sum of a priori information and the information obtained after testing. In general, the results have shown that the somatic mutation score test using soybean leaves is at least as efficient as the well-known tests that are generally used now, such as the Ames test and the chromosome aberration score test using mammalian cells in vitro. This test may be promising for the formation of efficient short-term test batteries.

[Dependence of the carcinogenicity of nitro compounds on their structural characteristics].

A new approach to the description of quantitative structure-activity relationships (QSAR analysis) based on compound descriptors has been used. The effect of the structural characteristics of nitric compounds on their carcinogenicity has been studied. It has been found that the carcinogenicity of nitric compounds is determined by the presence of furyl and/or azole heterocycles not condensed with benzene rings in their molecular structures. The carcinogenicity of the nitric compounds in which the benzene ring is the basic structure is determined by the presence of other substituents (halogens, amines, and methyl groups) and their positions relative to the nitro group.

[Use of ensemble structural descriptors for increasing the efficiency of QSAR study].

A new concept of describing the dependence of the mutagenic activity of a chemical substance on its structure (QSAR analysis) is presented. It involves ensemble descriptors, which are combinations of unrelated fragments of molecular structure. Software has been developed to generate various structural fragments of molecules and their combinations (ensembles) and select ensemble descriptors of statistical significance for the biological activity of a chemical. By examples of univocal ensemble descriptors consisting of two structural fragments and present only in active or only in inactive compounds, it has been shown that the efficiency of QSAR study can be increased fourfold or more. The approach has been applied to a set of 105 compounds whose mutagenic effect on rodent sex cells is known.

Inhibition of the bacterial mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine by ascorbic acid and ascorbyl palmitate.

The mechanism of antimutagenic activity of ascorbic acid (AA) and its derivatives was studied using the Salmonella typhimurium TA100 bacterial test system. All substances studied inhibited N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced mutagenesis. Ascorbyl palmitate (AP) markedly decreased the numbers of his+ revertants, behaving as a membrane-active antimutagen. A comparative study of the antioxidative activity of the investigated substances in the methyl oleate (MO) system has demonstrated that AA and its derivatives have pro-oxidant properties within the limits of the concentrations studied. The results obtained do not agree with the common view of the mode of action of these antimutagens, including both inhibition of free radical processes and MNNG reductive inactivation.

Antimutagenicity of propionic acid bacteria.

The antimutagenic effect of dialysed cell extracts of 4 strains of propionic acid bacteria was examined against the mutagenicity of sodium azide in the TA1535 tester strain of Salmonella typhimurium using the Ames test. It was noted that dialysates of 2 strains of Propionibacterium shermanii, P. pentosaceum and P. acnes, significantly reduced sodium azide-induced revertants. The dialysate of propionic acid cocci did not show an antimutagenic effect. The inhibitory activity was enhanced if the mutagen and extract were coincubated for 20 min prior to performing the mutagenicity assay. Antimutagenicity of dialysates from P. shermanii VKM-103 against MNNG and 9-aminoacridine was shown in S. typhimurium strains TA1535 and TA97. The antimutagenic activity was found in the protein fraction of the cell extract of P. shermanii. The proteins of the dialysate of P. shermanii were separated using a Toyopearl gel column into 3 main peaks according to their molecular weights. The antimutagenic activity towards sodium azide was found in the second and the third peaks. We suggest that dialysates of the cells of propionic acid bacteria contain several kinds of antimutagenic substances with different molecular weights.

Isolation and analysis of UV and radio-resistant bacteria from Chernobyl.

The accident at the Chernobyl nuclear power station in 1986 led to the dispersal of large amounts of a variety of radioactive materials, most importantly uranium, plutonium, 137Cs, 131I and 90Sr, over very large distances estimated to reach as far as Sweden, Norway, Turkey and possibly the USA. As a consequence, the soil on which the radioactive materials fell was contaminated and the degree of contamination varied with distance from the station, the direction and strength of the wind and the amount of atmospheric scavenging by rainfall at that time. Some of the radioactive materials have left a significant impact on mankind in the form of chromosomal aberrations including trisomy, various forms of cancers and death, whilst others are still in the ground where they will remain for a prolonged period to continue to exert their effects. Likewise, microbes living in the soil and exposed to radioactive materials may have been affected in a number of ways; some perished, and others survived due to the acquisition of advantageous mutation. Six years after the accident, soil samples contaminated with different levels of radioactivity were obtained from five regions within a 30 km radius of the nuclear power plant. From these soil samples spore-forming bacilli were isolated, quantified, identified and tested for resistance to X-rays, UVC and 4-nitroquinoline 1-oxide (4NQO). As a control, spore-forming bacilli were obtained from 'Zeleny mys' (an area 50 km south-east of the power station and emitting basal levels of radioactivity). A mutant of Escherichia coli hyper-resistant to a variety of DNA-damaging agents and its parent strain were also included in the study. Analysis of results reveals that a proportion of isolates of the same species from near the power station and the E. coli mutant SA236 were more resistant to X-rays, UVC and 4NQO compared with isolates from the control site and the E. coli parent strain, KL14, respectively.