The maintenance of genome stability is critical for health, but during individual ontogenesis, different stressors affect DNA integrity, which can lead to functional and/or structural changes in the cells of target organs. In the nervous system, cell genome destabilization is associated with different neurological and psychiatric diseases, but experiments in vivo, where a link between stress and DNA instability has been demonstrated, are relatively rare. Here, we use rat strains selected for the contrast excitability of the tibialis nerve (n. tibialis) and nonselected Wistar rats to investigate the reasons for individual differences in developing post-stress pathologies. Previous research on the behavioral response of these strains to prolonged emotional-painful stress (PEPS) allows us to consider one strain as a model of post-traumatic stress disorder (PTSD) and another strain as a model of compulsive disorder (CD). We study DNA damage in the cells of the prefrontal cortex (PFC), hippocampus, and amygdala, regions involved in stress responses and the formation of post-stress dysfunctions. The evaluation of cell genome integrity via the comet assay shows different responses to PEPS in each brain area analyzed and for all strains used. This could help us to understand the reasons for individual differences in the consequences of stress and the pathophysiology of post-stress disease formation.

Stress-reaction developed after exposure to stressors of different natures, increases the level of DNA damage in cells of target organs, including the central nervous system. However, the time of stressing exposure needed to induce genome destabilization in different brain areas and individual differences in animals defining their brain cell genome response to stressors is unclear. In this research, we show that acute stressors (2-h immobilization or 13-min emotional-painful stressor) increase the level of DNA damage in at least one of the brain regions studied: the prefrontal cortex, hippocampus, and amygdala in rat strains with the high or low threshold of nerve tibialis excitability, and non-selected Wistar rats. The results reveal the interstrain differences in the genome response to acute stressors of each brain area, different from the repeated emotional-painful stressor effects shown earlier.

Background. The epigenome of gametes is formed under the control of the developmental programme and the influence of environmental factors. How cytosine oxidation patterns are formed and altered in human spermatogenesis remains obscure so far. The aim of the study was to assess 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) patterns in human spermatogenic cells and spermatozoa. Materials and Methods. The study was performed on testicular biopsy samples of 10 azoospermic patients and ejaculate samples of 5 sperm donors and 8 patients from infertile couples. The microscope slides were prepared for further indirect immunofluorescence to detect 5fC and 5caC and FISH to determine spermatogenic cell ploidy. Results. 5fC and 5caC were undetectable in mitotic and meiotic chromosomes of spermatogenic cells, and was present exclusively in some spermatogonia and spermatid interphase nuclei as well as in some ejaculated spermatozoa. The frequency of spermatozoa with 5fC and 5caC varied in a wide range and was higher in patients than in sperm donors (p=0,007, p=0,028). The increase in frequency of spermatozoa with 5fC and 5caC was accompanied with the decrease in frequency of morphologically normal and progressively motile spermatozoa. Conclusions. 5fC and 5caC are differentially distributed in human spermatogenic cells and spermatozoa. The immunocytochemically detected increase of 5fC and 5caC in individual spermatozoa is most likely induced by oxidative stress caused by effects of internal and external factors rather than developmental programme. The evaluation of 5fC and 5caC in spermatozoa can be potentially used as an additional criterion of ejaculate quality.

Different stressors, while affecting the cells of target organs, can lead to genome instability and even disintegration, which can matter in the formation of post-stress disorders. We studied the effect of psycho-emotional stressors (immobilization and the house mouse female pheromone 2,5-dimethylpyrazine) on DNA integrity of hippocampal and bone marrow cells in CD-1, CBA and C3H male mice, using the cytogenetic and immunocytochemical methods (alkaline comet assay, ana-telophase test for mitotic disturbances, γH2AX focus assay). It was shown that both immobilization and 2,5-dimethylpyrazine cause genome damage in the cells of both organs studied. Cell genome destabilization in various organs is considered as an essential stage of stress response development in an attempt of the organism to adapt to extreme environmental exposures.

Variability of terry flowers in buttercup Ranunculus acris from different populations demonstrates the anthropogenic impact on the environment. Schoolchildren carried out training works analyzing the frequency of occurrence of the trait double of a buttercup flower in the populations of the North-West Region of Russia. The data obtained made it possible to discuss questions about the mechanisms of action of environmental pollution by surfactants and unsaturated hydrocarbons. The article emphasizes the importance: of the direct joint participation of schoolchildren and university professional teachers in environmental research; of the visibility, evidence and significance of their results; of competent comprehensive discussion for the formation of a bio- and ecocentric worldview. The latter is especially important for the tuition of qualified scientific staff in the field of ecological genetics.

Population density is known to affect the health and survival of many species, and is especially important for social animals. In mice, living in crowded conditions results in the disruption of social interactions, chronic stress, and immune and reproductive suppression; however, the underlying mechanisms remain unclear. Here, we investigated the role of chemosignals in the regulation of mouse physiology and behavior in response to social crowding. The pheromone 2,5-dimethylpyrazine (2,5-DMP), which is released by female mice in crowded conditions, induced aversion, glucocorticoid elevation and, when chronic, resulted in reproductive and immune suppression. 2,5-DMP olfaction induced genome destabilization in bone marrow cells in a stress-dependent manner, providing a plausible mechanism for crowding-induced immune dysfunction. Interestingly, the genome-destabilizing effect of 2,5-DMP was comparable to a potent mouse stressor (immobilization), and both stressors led to correlated expression changes in genes regulating cellular stress response. Thus, our findings demonstrate that, in mice, the health effects of crowding may be explained at least in part by chemosignals and also propose a significant role of stress and genome destabilization in the emergence of crowding effects.

Changes of genome stability in hippocampal cells of male rats with hereditary high and low thresholds of nervus tibialis response to electric stimuli (HT and LT strains, respectively) were studied in unstressed and stressed animals. HT and LT originated from Wistar strain, males of which were also used as a control. The comet assay was used after prolonged emotional painful stressor action. There were no interstrain differences in the spontaneous percentage of DNA in comet tails (tDNA). However, the prolonged emotional pain stressor induced genome instability differently in animals of different strains. The highest level of DNA damage in hippocampal cells was shown in highly sensitive animals of LT strain. Males of Wistar strain had intermediate levels of tDNA, while HT animals had the lowest stress reactivity.

It seems, that historically the problem of oppose inherited features vs acquired is mainly two-causes problem. The first is an insufficient knowledge about mechanisms how acquired phenotypic feature could became inherited. The second is semiotic or more precisely semantic. Any language itself contained the seeds of the problem because of ambiguous interpreting of same terms by different scientists. Human specific understanding of any term, which depends on their different education, specificity of different languages, usage of metaphors and analogies, etc., create unintended illusions of real truth. This brief theoretical study attempts to consider adaptively significant traits as gradually moving from the category of non-heritable to heritable ones. The conceptual approach used makes it possible to erase the contradictions between the interrelated concepts of acquired and inherited features.

Ambiguity of genetic terms usage leads to their misinterpretation and learning difficulties. The content of some concepts is analyzed as well as haziness and mistakes in usage of corresponding terms such as gene, allele, genotype, phenotype, polymorphism, heritability, variability and few others. Limitations of the model dividing separately impact of the environment and genotype in a feature formation are explored. The interaction of the environment and hereditary material is suggested as basic factor of genetic and phonetic variability.

BACKGROUND: Different stressors affect the genome integrity, but the mechanisms of such action are underexplored. MATERIALS AND METHODS: Bone marrow and testicular cells of CBA and CD-1 mouse males were used to estimate their genome integrity after stressor action by the comet assay. RESULTS: It is shown here that restraint and 2,5-dimethylpyrazine both increase damaged cell frequency in bone marrow as well as in testes of mouse males. For the first time the effect of immobilization and 2,5-dimethylpyrazine in testicular cells is demonstrated using the comet assay. Both stressors have similar effects in cells of both tissues analyzed. CONCLUSION: Mechanisms of the effects and possible role in microevolution are under discussion.

We studied changes in the stability of the genome in cells of two brain regions (prefrontal cortex and hippocampus), as well as in the bone marrow of rats with a hereditary high and low thresholds of excitability of the nervous system (strains HT and LT, respectively) after prolonged exposure with emotional-pain stressor. To study the reactivity of the brain cells genome, phosphorylated histone -H2AX (-H2AX phospho Ser139) was used. The level of mitotic disturbances in bone marrow cells was also assessed. Between the animals of the control groups, there were no interstrain differences in the studied parameters. Stress exposure increases the immunoreactivity to -H2AX phospho Ser139 of the prefrontal cortex cells and the level of chromosomal aberrations in bone marrow cells in animals of both strains. In cells of the dentate gyrus of the hippocampus, a specific increase in immunoreactivity to -H2AX phospho Ser139 was revealed in rats of the low-excitable HT strain. The relationship between the reaction of cells of this zone of hippocampus to the stressor exposure with the hereditary level of excitability of the nervous system of animals is discussed.

Too broad understanding of the term stress, which Selye himself and his followers used in their popular science works, reduces its scientific value. Based on a brief analysis of examples of the ambiguity of the term stress, it is proposed to restore its research significance. For that, the concept of stress should be used more strictly and unequivocally and it would not be allowed to use a commonly broad understanding the term in scientific papers. In the frame of earlier Selyes stress definition, it suggests a more detailed structuring of the term based on levels of studying of living objects, including genetic.

Сhromosomal machinery of highly excited animals with low threshold of the nervous system excitability (LT strain) is more susceptible to the damaging effect of high frequency EMR compared against the animals with high threshold of the nervous system excitability (HT strain). High nervous system excitability determines greater decrease in chromosome aberrations level in the presence of additional reflecting elements Aires Defender Pro resonators under UHF-waves of standard Wi-Fi router. It is shown that the genotype of animals and the functional state of their nervous system affect susceptibility to the UHF EMR and the action of resonators.

It is well known that in mice some pheromones modify reproductively important features. But the genetic mechanisms underlying such changes remain insufficiently studied. Here we show that in laboratory mice (Mus musculus L.), volatile signal 2,5-dimethylpyrazine excreted by donor stressed females increases the level of structural chromosome aberrations and other meiotic disturbances in spermatocytes of recipient males after nasal contact with the volatiles via sniffing. These chemosignals (i.e. pheromones) also induce abnormalities of sperm heads in the recipient mice. We assume that visible macro-damages at the chromosome level in meiotic cells are marks of a more widely disturbing effect (not only macro- but also micro-damages) of some olfactory signals in meiotic cells. It is most probable that the effects of volatile cues are mediated by the nervous system of the recipient organism. While gross chromosomal aberrations lead mainly to death of damaged cells, some of them (micro-damages of the chromosomes) might reach spermatozoa, and we detected part of them as anomalous sperm heads. Such abnormalities can reduce the fertilizing capacity of sperm. Moreover, some of the mutations induced by density-dependent volatile chemosignals can reach the progeny and influence the quantity and genetic quality of future generations. Possible microevolutionary consequences are discussed.

Failure to understand the role of biological and social factors in the formation of some socially important traits in humans could result in unjustified tension in interpersonal relationships. It is caused by a distorted perception of frequently unreliable information, its ambiguity due to the uncertainty of the terminology used and, as a consequence, the impossibility of its correct analysis. Using the term sexual orientation demonstrated the way how genetic understanding of the trait’s formation and data on the control mechanisms of sex formation may clarify and complement our knowledge on the subject. The hypothesis of the chemocommunicative model in the formation of sexual orientation in humans is discussed.

Current data on the effects of stress at the level of the cell genomes of the central nervous system and peripheral organs in animals are discussed. Regulatory and structural genomic changes in the cells of the central nervous system under stress are considered as a mechanism for regulating the functions of the brain and peripheral organs that form the organism manifestations of stress. Based on the Yu.Ya. Kerkis and M.E. Lobashev point of view, we consider stress as a special physiological state of the nervous system, affecting the work and integrity of the genome in target cells in animals, and thus playing a major role in microevolutionary transformations.

The effect of urine chemosignals of domestic male cats (Felis catus L.) on the stability of the bone marrow cell genome and corticosterone level in blood plasma of recipient mice (Mus musculus L.) is studied. It is demonstrated that a two-hour sniffing of volatile chemosignals leads to an increase in the frequency of bone marrow cells with damaged DNA, while 24 h exposure to chemosignals leads to an increase of chromosomal aberrations frequency in these cells. Thus, the effect of genomic instability induction in bone marrow cells of house mice by predator’s chemosignals is for the first time demonstrated in the work. At the same time, no increase in the corticosterone level is detected in the blood plasma either 30 or 60 min after the beginning of the exposure to the chemosignals of cat urine (CU). The physiological factors contributing to DNA damages accumulation in bone marrow cells, as well as the long-term consequences of the effect of these chemosignals on the genome stability, are discussed.

Background. Pheromones are an important regulatory link of synecological contacts in numerous animal species. Chemo-signaling participates in establishing of population social structure, it regulates different types of behavior, changes hormonal state and maturation rate, etc. It also can affect the genetic material expression and integrity. Material and methods. Groups of adult males of CBA/Lac/Sto/Rap strain were exposed to volatile chemosignals (mixture of - and -farnesenes or 2,5-dime thylpyrazine) for 2 or 24 hours. Bone marrow cells were prepared for single cell gel electrophoresis (comet assay test). Content of DNA in comet cells were analyzed. In case of 24 hours exposure bone marrow cells were fixed also for ana-telophase analysis. Results. It is shown that exposures with farnesenes or 2,5-DMP both damage genetic material of bone marrow cells. It also followed by induction of mitotic aberration frequency. Simultaneous exposure with all chemosignals does not increase damaging effect. Conclusion. Chemosignals which serve as stress-pheromones in mice decrease also the integrity of genetic material in bone marrow cells of recipients. It could be a mechanism of pheromonal impact on density and space-genetic structure of mouse populations.

We performed immunofluorescent analysis of DNA hydroxymethylation and methylation in human testicular spermatogenic cells from azoospermic patients and ejaculated spermatozoa from sperm donors and patients from infertile couples. In contrast to methylation which was present throughout spermatogenesis, hydroxymethylation was either high or almost undetectable in both spermatogenic cells and ejaculated spermatozoa. On testicular cytogenetic preparations, 5-hydroxymethylcytosine was undetectable in mitotic and meiotic chromosomes, and was present exclusively in interphase spermatogonia Ad and in a minor spermatid population. The proportions of hydroxymethylated and non-hydroxymethylated diploid and haploid nuclei were similar among samples, suggesting that the observed alterations of 5-hydroxymethylcytosine patterns in differentiating spermatogenic cells are programmed. In ejaculates, a few spermatozoa had high 5-hydroxymethylcytosine level, while in the other ones hydroxymethylation was almost undetectable. The percentage of highly hydroxymethylated (5-hydroxymethylcytosine-positive) spermatozoa varied strongly among individuals. In patients from infertile couples, it was higher than in sperm donors (P<0.0001) and varied in a wider range: 0.12-21.24% versus 0.02-0.46%. The percentage of highly hydroxymethylated spermatozoa correlated strongly negatively with the indicators of good semen quality - normal morphology (r=-0.567, P<0.0001) and normal head morphology (r=-0.609, P<0.0001) - and strongly positively with the indicator of poor semen quality: sperm DNA fragmentation (r=0.46, P=0.001). Thus, the immunocytochemically detected increase of 5hmC in individual spermatozoa is associated with infertility in a couple and with deterioration of sperm parameters. We hypothesize that this increase is not programmed, but represents an induced abnormality and, therefore, it can be potentially used as a novel indicator of semen quality.

It is shown by single-cell gel electrophoresis that the exposure of CBA mouse males with pheromone 2,5-dimethylpyrazine for 4 or 24 h increases DNA damage level in interphase nuclei of bone marrow cells. The results may reflect the work of a mechanism of formation of chromosomal aberrations and other mitotic disturbances, detected at the stage of ana-telophase, the frequency of which in dividing bone marrow cells increased after similar pheromonal exposure. The comparison of the damaged cell distribution types is proposed as an approach to analysis of comet assay data. The significance of the revealed effects on the immune system in the recipient organism is discussed.