DNA methylation differences in genes associated with human personal disorders and deviant behavior.

Epigenetic regulation of gene expression is involved in the progression of mental disorders, including deviant behavior, brain developmental, and personality disorders. The large number of genes has been studied for their activity association with stress and depression; however, the obtained results for the majority of these genes are contradictory. The aim of our study was to investigate the possible contribution of methylation level changes to the development of personality disorders and deviant behavior. A systematic study of CpG Islands in 21 target regions, including the promoter and intron regions of the 12 genes was performed in DNA samples extracted from peripheral blood cells, to obtain an overview of their methylation status. High-throughput sequencing of converted DNA samples was performed and calling of the methylation sites on the "original top strand" in CpG islands was carried out in the Bismark pipeline. The initial methylation profile of 77 patients and 48 controls samples revealed a significant difference in 7 CpG sites in 6 genes. The most significant hypermethylation was found for the target sites of the HTR2A (p-value = 1.2 × 10-13) and OXTR (p-value = 2.3 × 10-7) genes. These data support the previous reports that alterations in DNA methylation may play an important role in the dysregulation of gene expression associated with personality disorders and deviant behavior, and confirm their potential use as biomarkers to improve thediagnosis, prognosis, and assessment of response to treatment.

[Genetic effects of bystander factors from the blood sera of people irradiated as the result of the Chernobyl accident].

The purpose of this work was the analysis of the effects of bystander factors from blood sera of people affected by the Chernobyl accident on human keratinocyte cell culture (HPV-G cells). A new method was developed for evaluation of the bystander factor presence in vivo in blood of the people irradiated by the Chernobyl accident. Affected population groups included liquidators of the Chernobyl accident and people living and working in areas of the Gomel region contaminated by radionuclides. The analysis has shown that bystander factors persist in Chernobyl liquidator blood samples for more than 20 years since irradiation. The data suggest that blood sera contain bystander factors, which are able to induce micronuclei and decrease the metabolic activity of HPV-G cells.

[Genetic monitoring of natural Drosophila populations in radiation contaminated regions of Belarus].

Genetic monitoring of natural Drosophila melanogaster populations inhabiting regions of Belarus with different radiation background (Vetka and Svetilovichi villages), radonuclide-contaminated after the Chernobyl accident, compared with populations from the Berezinsky biosphere reserve (the control area) were conducted. The dominant and recessive lethal mutation levels and genetic structure of the populations were analyzed for frequencies of F- and S-alleles of Adh (alcohol dehydrogenase) of Gpdh (glycerinophosphate dehydrogenase) and Sod (superoxide dismutase) loci. Populations inhabiting the regions with high radiation background exhibited higher frequency of lethal mutations and higher heterozygosity than those from the control area. Moreover, higher frequency of polymorphous Sod locus S-allele was detected in these populations. Apparently, Sod S-alleles are more adaptively valuable under conditions of high radiation background, because as is known, superoxide dismutase is an effective radioprotector at all levels molecular, cellular and organism. Adaptation of populations to stress impacts was analyzed, since 1998. Nonspecific adaptation of natural Drosophila melanogaster populations from Vetka and Svetilovichi villages of Gomel region was reveled. They are higher adapted than the control population from the Berezinsky biosphere reserve to both ionizing radiation effect and to chemical mutagen EMS. After laboratory cultivation within 6-8 generations without irradiation adaptation to radiation in the population from radiocontaminated regions remained. The content of samples from the control natural drosophila population in the laboratory conditions is an environmental stress that led to the formation of nonspecific adaptation within 6-8 generations to unfavorable factors, including ionizing radiation. It should be taken into account that the population adaptation is formed via death of sensitive genotypes at various ontogenesis stages.

Influence of melanin on mutation load in Drosophila populations after long-term irradiation.

The effect of melanin on the level of mutation load has been studied in experimental Drosophila populations exposed to radiation for 115 generations. Four types of populations have been analyzed: (1) control; (2) treated with melanin; (3) irradiated; (4) irradiated and treated with melanin. Melanin was produced by auto-oxidation of 1-dioxyphenylalanine and was constantly added to food. Populations were X-irradiated twice in each generation (at the larvae stage with 6 Gy and at the imago stage with 9 Gy). The level of recessive mutation on the third chromosome was analyzed by a standard genetic method of balanced lethals. The data obtained have shown that the populations exposed to long-term irradiation have the greatest number of mutations decreasing viability. Melanin exhibited radioprotective properties--it reduced the percentage of lethal, semilethal and subvital mutations. Thus the possibility of effective protection of populations exposed to radiation for many generations by melanin has been shown for the first time.

[Modern problems of biodosimetry]. / Sovremennye problemy biodozimetrii.

Humans have different radiosensitivity. Besides, many factors which are not under control can change significantly biological effects of radiation. Some of substances are present in our food--residual amounts of fertilizers or herbicides can be mutagenic or influence mutagenic action of radiation. In the last case synergetic or antagonistic effects can be observed. At the same time many food products contain radioprotectors or antimutagens. Some drugs, stress, virus diseases and so on can change biological effects of radiation too. Radioadaptive response is one of the most significant factors which can be responsible for incorrect radiation dose evaluation. All these uncontrolled factors may be responsible for significant mistakes of evaluating radiation dose by biological methods. That is why biological methods can be used for bioindication but not for biodosimetry.

[Adaptation processes in natural Drosophila populations in radiation contaminated Belarus regions before and after radiation exposure removal]. / Protsessy adaptatsii prirodnykh populiatsii drozofily iz radiatsionno-zagriaznennykh raionov Belarusi do i posle sniatiia radiatsionnoi nagruzki.

We have shown that natural drosophila populations from the settlement Vetka of Gomel region with increased radiation background are more adapted to mutagenic effect of radiation than drosophila populations from Berezinsky reserve (the control). After the populations were placed into laboratory thermostat adaptation of Vetka population remained within 6-8 generations without irradiation. However the control population became more resistant too. So, the keeping of natural drosophila populations under laboratory conditions was a stress and led to unspecific adaptation the same as a low level of radiocontamination did. These facts should be considered in studying dynamics of the mutation level during radionuclide removal in animals caught in radiocontaminated regions and placed in vivaria conditions.

[Study on genetic radioresistance of natural Drosophila Melanogaster population from radionuclide contaminated regions of Byelarus]. / Issledovanie geneticheskoi radiochuvstvitel'nosti prirodnykh populiatsii Drosophila melanogaster iz zagriaznennykh radionuklidami raionov Belarusi.j

Over the period from 1998 to 2000 adaptation to unfavorable ecological factors was revealed to be formed in natural Drosophila melanogaster populations from various regions of Belarus with increased radiation background due to the Chernobyl accident. This adaptation was shown to be of non-specific character, since the populations from radiation regions were more resistant to the effect of not only factors of physical nature (irradiation), but also to that of chemical mutagen ethylmethanesulphonate. Assessment of population resistance was carried out by means of tests of dominant lethal mutations and recessive sex-linked lethal mutations.

[Effect of melanin on mutagenic activity of chronic irradiation and adaptive response in mice]. / Vliianie melanina na mutagennoe deistvie khronicheskogo oblucheniia i adaptivnyi otvet u myshei.

Pigment melanin peroral injection was shown to decrease significantly mutagenic action of chronic irradiation at low dose rate (0.007 Gy/h), and melanin protection against chronic irradiation is even more effective than against acute one. A phenomenon of radioadaptive response was revealed in mice in vivo by tests of chromosome aberrations in bone marrow cells and reciprocal translocations in germ cells. Adaptive response before priming dose was not observed if melanin was injected. If melanin was applied between conditioning and basic doses both radioprotective and adaptive effects were observed.