Galina Hovhannisyan - Academia.edu (original) (raw)

Papers by Galina Hovhannisyan

Research paper thumbnail of Assessment of aquatic genotoxicity of the Lake Sevan basin, Armenia using natural bioindicators

ARPHA Conference Abstracts

Water pollution can cause genomic instability, thereby threatening aquatic wildlife and human hea... more Water pollution can cause genomic instability, thereby threatening aquatic wildlife and human health․ For a correct assessment of the impact of the mixture of pollutants, chemical analysis of environmental contaminants should be simultaneously applied with genotoxicity assays. The сomet assay is a sensitive, versatile and extensively used method for genotoxicity assessment in a water environment and was successfully applied in aquatic wild species, including fish and crayfish. Earlier we investigated the genotoxicity of waters of the Lake Sevan basin (Simonyan et al. 2016, Simonyan et al. 2019)․ Lake Sevan is the largest lake of the Caucasus Region, situated in the Republic of Armenia, in the Gegharkunik Province. Water pollution in the lake is a result of both anthropogenic and natural pressures. A combination of comet assay (Tice et al. 2000) and chemical analysis was applied for evaluation of water genotoxicity using gibel carp Carassius auratus gibelio and crayfish Astacus lepto...

Research paper thumbnail of Doxorubicin-Induced Translocation of mtDNA into the Nuclear Genome of Human Lymphocytes Detected Using a Molecular-Cytogenetic Approach

International Journal of Molecular Sciences

Translocation of mtDNA in the nuclear genome is an ongoing process that contributes to the develo... more Translocation of mtDNA in the nuclear genome is an ongoing process that contributes to the development of pathological conditions in humans. However, the causal factors of this biological phenomenon in human cells are poorly studied. Here we analyzed mtDNA insertions in the nuclear genome of human lymphocytes after in vitro treatment with doxorubicin (DOX) using a fluorescence in situ hybridization (FISH) technique. The number of mtDNA insertions positively correlated with the number of DOX-induced micronuclei, suggesting that DOX-induced chromosome breaks contribute to insertion events. Analysis of the odds ratios (OR) revealed that DOX at concentrations of 0.025 and 0.035 µg/mL significantly increases the rate of mtDNA insertions (OR: 3.53 (95% CI: 1.42–8.76, p < 0.05) and 3.02 (95% CI: 1.19–7.62, p < 0.05), respectively). Analysis of the distribution of mtDNA insertions in the genome revealed that DOX-induced mtDNA insertions are more frequent in larger chromosomes, which a...

Research paper thumbnail of DNA Copy Number Variations as Markers of Mutagenic Impact

International Journal of Molecular Sciences

DNA copy number variation (CNV) occurs due to deletion or duplication of DNA segments resulting i... more DNA copy number variation (CNV) occurs due to deletion or duplication of DNA segments resulting in a different number of copies of a specific DNA-stretch on homologous chromosomes. Implications of CNVs in evolution and development of different diseases have been demonstrated although contribution of environmental factors, such as mutagens, in the origin of CNVs, is poorly understood. In this review, we summarize current knowledge about mutagen-induced CNVs in human, animal and plant cells. Differences in CNV frequencies induced by radiation and chemical mutagens, distribution of CNVs in the genome, as well as adaptive effects in plants, are discussed. Currently available information concerning impact of mutagens in induction of CNVs in germ cells is presented. Moreover, the potential of CNVs as a new endpoint in mutagenicity test-systems is discussed.

Research paper thumbnail of Analysis of copy number variations induced by ultrashort electron beam radiation in human leukocytes in vitro

Molecular Cytogenetics

Background: Environmental risk factors have been shown to alter DNA copy number variations (CNVs)... more Background: Environmental risk factors have been shown to alter DNA copy number variations (CNVs). Recently, CNVs have been described to arise after low-dose ionizing radiation in vitro and in vivo. Development of cost-and size-effective laser-driven electron accelerators (LDEAs), capable to deliver high energy beams in pico-or femtosecond durations requires examination of their biological effects. Here we studied in vitro impact of LDEAs radiation on known CNV hotspots in human peripheral blood lymphocytes on single cell level. Results: Here CNVs in chromosomal regions 1p31.1, 7q11.22, 9q21.3, 10q21.1 and 16q23.1 earlier reported to be sensitive to ionizing radiation were analyzed using molecular cytogenetics. Irradiation of cells with 0.5, 1.5 and 3.0 Gy significantly increased signal intensities in all analyzed chromosomal regions compared to controls. The latter is suggested to be due to radiation-induced duplication or amplification of CNV stretches. As significantly lower gains in mean fluorescence intensities were observed only for chromosomal locus 1p31.1 (after irradiation with 3.0 Gy variant sensitivites of different loci to LDEA is suggested. Negative correlation was found between fluorescence intensities and chromosome size (r = − 0.783, p < 0.001) in cells exposed to 3.0 Gy irradiation and between fluorescence intensities and gene density (r = − 0.475, p < 0.05) in cells exposed to 0.5 Gy irradiation. Conclusions: In this study we demonstrated that irradiation with laser-driven electron bunches can induce molecular-cytogenetically visible CNVs in human blood leukocytes in vitro. These CNVs occur most likely due to duplications or amplification and tend to inversely correlate with chromosome size and gene density. CNVs can last in cell population as stable chromosomal changes for several days after radiation exposure; therefore this endpoint can be used for characterization of genetic effects of accelerated electrons. These findings should be complemented with other studies and implementation of more sophisticated approaches for CNVs analysis.

Research paper thumbnail of Micronuclei and What They Can Tell Us in Cytogenetic Diagnostics

Current Genetic Medicine Reports

Research paper thumbnail of Application of the comet assay, micronucleus test and global DNA methylation analysis in Darevskia lizards as a sentinel organism for genotoxic monitoring of soil pollution

Mutation Research/Genetic Toxicology and Environmental Mutagenesis

Research paper thumbnail of DNA damage and micronuclei in parthenogenetic and bisexual Darevskia rock lizards from the areas with different levels of soil pollution

Ecotoxicology and environmental safety, Jan 15, 2018

Natural species are widely used as indicator organisms to estimate of the impact of environmental... more Natural species are widely used as indicator organisms to estimate of the impact of environmental pollution. Here we present the results of first study of a reliability of parthenogenetic Darevskia аrmeniaca and bisexual Darevskia raddei rock lizards as sentinels for monitoring of environmental genotoxicity. The comet assay and micronucleus test were applied to the lizards sampled in six areas in Armenia and Artsakh with different levels of soil contamination. The results obtained showed a clear relationship between the pollution level of lizards' habitats and the frequency of DNA damage in the comet assay. Low baseline frequency of micronuclei in D. аrmeniaca and D. raddei, however, makes this parameter ineffective for environmental genotoxicity evaluation. The parthenogenetic lizards D. аrmeniaca showed higher sensitivity toward genotoxic pollutions compared with bisexual D. raddei living in the same environment. The correlations between soil content of heavy metals Cr, Cu, Zn...

Research paper thumbnail of Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro

Journal of Radiation Research

Laser-generated electron beams are distinguished from conventional accelerated particles by ultra... more Laser-generated electron beams are distinguished from conventional accelerated particles by ultrashort beam pulses in the femtoseconds to picoseconds duration range, and their application may elucidate primary radiobiological effects. The aim of the present study was to determine the dose-rate effect of laser-generated ultrashort pulses of 4 MeV electron beam radiation on DNA damage and repair in human cells. The dose rate was increased via changing the pulse repetition frequency, without increasing the electron energy. The human chronic myeloid leukemia K-562 cell line was used to estimate the DNA damage and repair after irradiation, via the comet assay. A distribution analysis of the DNA damage was performed. The same mean level of initial DNA damages was observed at low (3.6 Gy/min) and high (36 Gy/min) dose-rate irradiation. In the case of low-dose-rate irradiation, the detected DNA damages were completely repairable, whereas the high-dose-rate irradiation demonstrated a lower l...

Research paper thumbnail of Effect of N-acetyl-L-cysteine on human chronic myeloid leukemia cells KCL22 treated with mitomycin C

Journal of Ecology and Environment, 2014

The effectiveness of N-acetyl-L-cysteine (NAC) to protect blood cells against Mitomycin C (MMC) i... more The effectiveness of N-acetyl-L-cysteine (NAC) to protect blood cells against Mitomycin C (MMC) induced genotoxicity was investigated in human chronic myeloid leukemia cells (KCL22) using the alkaline comet assay. The comet assay was selected as sensitive and rapid method for analysis of DNA damage and repair in individual cells. NAC treatment alone did not produce any damage in KCL22 cell. But NAC was found to be effective in reducing genotoxic damage in KCL22 cells exposed to MMC. These results confirm the literature data that, given the safety and ability to reduce DNA damage. NAC may be useful to prevent drug-mediated genotoxicity.

Research paper thumbnail of Comet-FISH

Springer Protocols Handbooks, 2016

Research paper thumbnail of Micronucleus FISH

Springer Protocols Handbooks, 2016

Research paper thumbnail of Comparative analysis of individual chromosome involvement in micronuclei induced by mitomycin C and bleomycin in human leukocytes

Molecular Cytogenetics, 2016

Background: Micronucleus (MN) assay is a well standardized approach for evaluation of clastogenic... more Background: Micronucleus (MN) assay is a well standardized approach for evaluation of clastogenic/aneugenic effects of mutagens. Fluorescence in situ hybridization (FISH) is successfully used to characterize the chromosomal content of MN. However, the relationships between nuclear positioning, length, and gene density of individual chromosomes and their involvement in MN induced by different mutagens have not been clearly defined. Results: Chromosomal content of MN was characterized in human leukocytes treated with mitomycin C (MMC) and bleomycin (BLM) by FISH using centromeric (cep) and whole-chromosome painting (wcp) probes. Involvement of chromosomes 8, 15 and 20 in MMC-induced and chromosomes 1, 9 and 16 in BLM-induced MN was studied, and correlated with chromosome size, gene density and interphase position. The results obtained were analyzed together with previous own data on the frequencies of inclusion of chromosomes 3, 4, 6, 7, 9, 16, 17, 18, and X in MMC-induced MN. It could be shown that MMC-and BLM-induced MN could contain material derived from all chromosomes investigated. Involvement of whole chromosomes 8, 15 and 20 in MMC-induced MN negatively correlated with gene density; however, analysis together with earlier studied chromosomes did not confirm this correlation. Inclusion of chromosomes 8, 15 and 20 in MMC-induced MN does not depend on their size and interphase position; the same result was found for the twelve overall analyzed chromosomes. In BLM-treated cells significant correlation between frequencies of involvement of chromosomes 1, 9 and 16 in MN and their size was found. Conclusions: Our results clearly revealed that BLM differs from MMC with respect to the distribution of induced chromosome damage and MN formation. Thus, DNA-damaging agents with diverse mechanism of action induce qualitatively different MN with regard to their chromosomal composition. Also this study demonstrates the utility of combined sequential application of cep and wcp probes for efficient detection of MN chromosomal content in terms of centric and acentric fragments.

Research paper thumbnail of Genotoxicity of Water Contaminants from the Basin of Lake Sevan, Armenia Evaluated by the Comet Assay in Gibel Carp (Carassius auratus gibelio) and Tradescantia Bioassays

Bulletin of Environmental Contamination and Toxicology, 2016

Combination of bioassays and chemical analysis was applied to determine the genotoxic/mutagenic c... more Combination of bioassays and chemical analysis was applied to determine the genotoxic/mutagenic contamination in four different sites of the basin of Lake Sevan in Armenia. Water genotoxicity was evaluated using the single cell gel electrophoresis technique (comet assay) in erythrocytes of gibel carp (Carassius auratus gibelio), Tradescantia micronucleus (Trad-MCN) and Tradescantia stamen hair mutation (Trad-SHM) assays. Significant inter-site differences in the levels of water genotoxicity according to fish and Trad-MCN bioassays have been revealed. Two groups of locations with lower (south-southwest of the village Shorzha and Peninsula of Lake Sevan) and higher (estuaries of Gavaraget and Dzknaget rivers) levels of water genotoxicity were distinguished. Correlation analysis support the hypothesis that the observed genetic alterations in fish and plant may be a manifestation of the effects of water contamination by nitrate ions, Si, Al, Fe, Mn and Cu. Increase of DNA damage in fish also correlated with content of total phosphorus.

Research paper thumbnail of Ruben M. Arutyunyan, Tamara F. Sarkisyan, Galina G. Oganesyan, Andrei D. Durnev Comparative investigation of anticlastogenic effects in cell cultures of healthy donors and patients with nettle-rash Mutation Research 1994 Mar;320(4):335-41

Mutation Research/Genetic Toxicology

In cultures of lymphocytes from 12 healthy donors and 12 patients with nettle-rash (NR) the antic... more In cultures of lymphocytes from 12 healthy donors and 12 patients with nettle-rash (NR) the anticlastogenic effect of the antimutagens WR-2721 (WR), bemitil (BM), tomerzol (TM) and interferon (IF) on the induction of chromosomal aberrations by photrin (PT) and dioxidine (DX) was investigated. There were no statistically significant differences between healthy donors and patients with NR in the levels of chromosomal aberrations that were spontaneous or induced by PT or DX. Statistically significant protective effects of BM, WR, TM and IF were demonstrated in cells of healthy donors after treatment with PT or DX, and after modification of the clastogenic action of PT in lymphocytes of NR patients.There was no protective effect of any of the anticlastogens after treatment of the lymphocyte cultures from NR patients with DX. That observation allows us to suggest the test of anticlastogenic action as a measure of sensitivity of the chromosomal apparatus in groups with different genetic r...

Research paper thumbnail of A New Case of a Complex Small Supernumerary Marker Chromosome: A Der(9)t(7;9)(p22;q22) due to a Maternal Balanced Rearrangement

Journal of Pediatric Genetics, 2015

Complex small supernumerary marker chromosomes (sSMCs) constitute one of the smallest subsets wit... more Complex small supernumerary marker chromosomes (sSMCs) constitute one of the smallest subsets within the patients with an sSMC. Complex sSMCs consist of chromosomal material derived from more than one chromosome, for example, the derivative der(22)t(11;22)(q23;q11.2) in Emanuel syndrome. Here, a yet unreported case of a complex sSMC formed due to a t(7;9)(p22;q22)mat is presented.

Research paper thumbnail of Comet-assay in combination with PNA-FISH detects mutagen-induced DNA damage and specific repeat sequences in the damaged DNA of transformed cells

International journal of molecular medicine, 2005

The Comet-assay was applied to three transformed cell lines (HT1080, CCRF-CEM line and CHO) which... more The Comet-assay was applied to three transformed cell lines (HT1080, CCRF-CEM line and CHO) which were treated with the cytostatics bleomycin (BLM) or mitomycin C (MMC). In addition, PNA probes for the telomere repeat (TTAGGG)(n) were used for detection of telomeric DNA sequences in the damaged DNA. Data were compared with previously obtained results from peripheral leukocytes. The amount of migrating DNA increased in all cell types in a dose-dependent manner after BLM exposure. CHO cells reacted sensitively at low doses of the mutagen, and leukocytes had the highest dose-related effect up to 25 IU/ml which, however, did not further increase. A rather linear dose response characterized the HT1080 cells, the effect was lowest for the CCRF-CEM cells. While MMC at lower doses increased the percentage of migrating DNA in a dose-dependent manner, the higher doses induced shorter comets, on average, than the lower ones in all cell lines. With PNA-Comet-FISH obvious differences were found ...

Research paper thumbnail of Combined Genotoxic Effects of Aflatoxin B1, Ochratoxin A and Zearalenone in Rat Bone Marrow and Blood Leukocytes

Mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA) are widespread ... more Mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA)
are widespread contaminants of food and feedstuffs. It is very likely, that humans and animals
are always exposed to mixtures of mycotoxins rather than to individual compounds. Therefore,
risk assessments should consider mixture toxicity data. In the present study the combination of
AFB1, OTA and ZEA was tested for genotoxicity in rat bone marrow and blood leukocytes after
15, 30 and 60 days treatment. The level of DNA damage was determined by the comet assay. The
tail intensity and Olive tail moment in leukocytes and bone marrow cells were significantly higher
than in controls. At the same time, the level of DNA damage in bone marrow cells was higher than
in leukocytes. The data suggests that prolonged exposure to mycotoxins combination through
food consumption can induce DNA damage contributing to the harmful effects in vivo.

Research paper thumbnail of Fragility of telomeres after bleomycin and cisplatin combined treatment measured in human leukocytes with the Comet-FISH technique

Experimental oncology, 2005

THE AIM of the present study was the comparative investigation of action of widely applied antica... more THE AIM of the present study was the comparative investigation of action of widely applied anticancer preparations: cisplatin (cis-DDP) and bleomycin (BLM) on total DNA and telomeres damage in human blood cells. The "Comet-FISH technique" -- single cell gel electrophoresis ("comet assay") in combination with fluorescent in situ hybridization (FISH) was used for this purpose. This newly applied combined approach permits to detect on the same specimen the total DNA damage in individual cells and evaluate specific DNA sequences as well. Telomere -- specific -- PNA (peptide nucleic acid) probes were used for the localization of telomeres in the comet's head and their migration to the tail. THE RESULTS obtained indicate that in control variants, due to DNA metabolism and handling, approximately 7% of the DNA and 17% of the telomeres were found in the tail. In cells treated with BLM alone, telomeres leak out with equal probability as total DNA. In turn, the combina...

Research paper thumbnail of Evaluation of cisplatin-DNA crosslinks formation with UV-C application by the alkaline Comet-assay

Experimental oncology, 2004

The AIM of the present study was to investigate DNA damage induced by widely applied anticancer p... more The AIM of the present study was to investigate DNA damage induced by widely applied anticancer preparation cisplatin (cis-DDP) at doses comparable with therapeutic ones in leukocytes of healthy donors. DNA damage and repair was estimated by the single cell gel electrophoresis or Comet-assay. For estimation of cis-DDP-induced DNA crosslinks the combined treatment by cis-DDP with the DNA damaging agent UV-C was used. The RESULTS obtained indicate that cis-DDP is forming crosslinks with DNA in human leukocytes and significantly reduce UV-C-induced DNA migration. The Comet-assay with UV-C application is a useful tool to detect cis-DDP- induced DNA crosslinks. Data on the cis-DDP-induced DNA damage in vitro may be important for their extrapolation on in vivo level.

Research paper thumbnail of Butyrate reduces the frequency of micronuclei in human colon carcinoma cells in vitro

Toxicology in Vitro, 2009

Butyrate, formed by bacterial fermentation of plant foods, has been shown to protect human colon ... more Butyrate, formed by bacterial fermentation of plant foods, has been shown to protect human colon cells from selected genotoxic substances. The mechanism for this effect could be the enhancement of toxicological defence leading to an increased detoxification of genotoxic risk factors and thus to a reduction of DNA and chromosome damage. Previous protective properties of butyrate against DNA damage induction in colon cells were demonstrated using the comet assay. In the present study the effect of butyrate on chromosome damage induced by ferric nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H 2 O 2 ) (suggested to be putative risk factors of colorectal carcinogenesis) was investigated using the cytokinesisblock micronucleus (CBMN) test. It was possible to reveal that pre-treatment of HT29 colon carcinoma cells with butyrate (2 and 4 mM) for 15 min caused a reduction of micronuclei induced with H 2 O 2 (75 lM; p < 0.01) and Fe-NTA (500 and 1000 lM; p < 0.05). The decrease in the level of Fe-NTA-and H 2 O 2 -induced micronuclei was also confirmed in most of the corresponding variants of 24 h pre-treatment of cells with butyrate. The results obtained demonstrate for the first time protective properties of butyrate against chromosome damage induced by H 2 O 2 and Fe-NTA in human colon carcinoma cells.

Research paper thumbnail of Assessment of aquatic genotoxicity of the Lake Sevan basin, Armenia using natural bioindicators

ARPHA Conference Abstracts

Water pollution can cause genomic instability, thereby threatening aquatic wildlife and human hea... more Water pollution can cause genomic instability, thereby threatening aquatic wildlife and human health․ For a correct assessment of the impact of the mixture of pollutants, chemical analysis of environmental contaminants should be simultaneously applied with genotoxicity assays. The сomet assay is a sensitive, versatile and extensively used method for genotoxicity assessment in a water environment and was successfully applied in aquatic wild species, including fish and crayfish. Earlier we investigated the genotoxicity of waters of the Lake Sevan basin (Simonyan et al. 2016, Simonyan et al. 2019)․ Lake Sevan is the largest lake of the Caucasus Region, situated in the Republic of Armenia, in the Gegharkunik Province. Water pollution in the lake is a result of both anthropogenic and natural pressures. A combination of comet assay (Tice et al. 2000) and chemical analysis was applied for evaluation of water genotoxicity using gibel carp Carassius auratus gibelio and crayfish Astacus lepto...

Research paper thumbnail of Doxorubicin-Induced Translocation of mtDNA into the Nuclear Genome of Human Lymphocytes Detected Using a Molecular-Cytogenetic Approach

International Journal of Molecular Sciences

Translocation of mtDNA in the nuclear genome is an ongoing process that contributes to the develo... more Translocation of mtDNA in the nuclear genome is an ongoing process that contributes to the development of pathological conditions in humans. However, the causal factors of this biological phenomenon in human cells are poorly studied. Here we analyzed mtDNA insertions in the nuclear genome of human lymphocytes after in vitro treatment with doxorubicin (DOX) using a fluorescence in situ hybridization (FISH) technique. The number of mtDNA insertions positively correlated with the number of DOX-induced micronuclei, suggesting that DOX-induced chromosome breaks contribute to insertion events. Analysis of the odds ratios (OR) revealed that DOX at concentrations of 0.025 and 0.035 µg/mL significantly increases the rate of mtDNA insertions (OR: 3.53 (95% CI: 1.42–8.76, p < 0.05) and 3.02 (95% CI: 1.19–7.62, p < 0.05), respectively). Analysis of the distribution of mtDNA insertions in the genome revealed that DOX-induced mtDNA insertions are more frequent in larger chromosomes, which a...

Research paper thumbnail of DNA Copy Number Variations as Markers of Mutagenic Impact

International Journal of Molecular Sciences

DNA copy number variation (CNV) occurs due to deletion or duplication of DNA segments resulting i... more DNA copy number variation (CNV) occurs due to deletion or duplication of DNA segments resulting in a different number of copies of a specific DNA-stretch on homologous chromosomes. Implications of CNVs in evolution and development of different diseases have been demonstrated although contribution of environmental factors, such as mutagens, in the origin of CNVs, is poorly understood. In this review, we summarize current knowledge about mutagen-induced CNVs in human, animal and plant cells. Differences in CNV frequencies induced by radiation and chemical mutagens, distribution of CNVs in the genome, as well as adaptive effects in plants, are discussed. Currently available information concerning impact of mutagens in induction of CNVs in germ cells is presented. Moreover, the potential of CNVs as a new endpoint in mutagenicity test-systems is discussed.

Research paper thumbnail of Analysis of copy number variations induced by ultrashort electron beam radiation in human leukocytes in vitro

Molecular Cytogenetics

Background: Environmental risk factors have been shown to alter DNA copy number variations (CNVs)... more Background: Environmental risk factors have been shown to alter DNA copy number variations (CNVs). Recently, CNVs have been described to arise after low-dose ionizing radiation in vitro and in vivo. Development of cost-and size-effective laser-driven electron accelerators (LDEAs), capable to deliver high energy beams in pico-or femtosecond durations requires examination of their biological effects. Here we studied in vitro impact of LDEAs radiation on known CNV hotspots in human peripheral blood lymphocytes on single cell level. Results: Here CNVs in chromosomal regions 1p31.1, 7q11.22, 9q21.3, 10q21.1 and 16q23.1 earlier reported to be sensitive to ionizing radiation were analyzed using molecular cytogenetics. Irradiation of cells with 0.5, 1.5 and 3.0 Gy significantly increased signal intensities in all analyzed chromosomal regions compared to controls. The latter is suggested to be due to radiation-induced duplication or amplification of CNV stretches. As significantly lower gains in mean fluorescence intensities were observed only for chromosomal locus 1p31.1 (after irradiation with 3.0 Gy variant sensitivites of different loci to LDEA is suggested. Negative correlation was found between fluorescence intensities and chromosome size (r = − 0.783, p < 0.001) in cells exposed to 3.0 Gy irradiation and between fluorescence intensities and gene density (r = − 0.475, p < 0.05) in cells exposed to 0.5 Gy irradiation. Conclusions: In this study we demonstrated that irradiation with laser-driven electron bunches can induce molecular-cytogenetically visible CNVs in human blood leukocytes in vitro. These CNVs occur most likely due to duplications or amplification and tend to inversely correlate with chromosome size and gene density. CNVs can last in cell population as stable chromosomal changes for several days after radiation exposure; therefore this endpoint can be used for characterization of genetic effects of accelerated electrons. These findings should be complemented with other studies and implementation of more sophisticated approaches for CNVs analysis.

Research paper thumbnail of Micronuclei and What They Can Tell Us in Cytogenetic Diagnostics

Current Genetic Medicine Reports

Research paper thumbnail of Application of the comet assay, micronucleus test and global DNA methylation analysis in Darevskia lizards as a sentinel organism for genotoxic monitoring of soil pollution

Mutation Research/Genetic Toxicology and Environmental Mutagenesis

Research paper thumbnail of DNA damage and micronuclei in parthenogenetic and bisexual Darevskia rock lizards from the areas with different levels of soil pollution

Ecotoxicology and environmental safety, Jan 15, 2018

Natural species are widely used as indicator organisms to estimate of the impact of environmental... more Natural species are widely used as indicator organisms to estimate of the impact of environmental pollution. Here we present the results of first study of a reliability of parthenogenetic Darevskia аrmeniaca and bisexual Darevskia raddei rock lizards as sentinels for monitoring of environmental genotoxicity. The comet assay and micronucleus test were applied to the lizards sampled in six areas in Armenia and Artsakh with different levels of soil contamination. The results obtained showed a clear relationship between the pollution level of lizards' habitats and the frequency of DNA damage in the comet assay. Low baseline frequency of micronuclei in D. аrmeniaca and D. raddei, however, makes this parameter ineffective for environmental genotoxicity evaluation. The parthenogenetic lizards D. аrmeniaca showed higher sensitivity toward genotoxic pollutions compared with bisexual D. raddei living in the same environment. The correlations between soil content of heavy metals Cr, Cu, Zn...

Research paper thumbnail of Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro

Journal of Radiation Research

Laser-generated electron beams are distinguished from conventional accelerated particles by ultra... more Laser-generated electron beams are distinguished from conventional accelerated particles by ultrashort beam pulses in the femtoseconds to picoseconds duration range, and their application may elucidate primary radiobiological effects. The aim of the present study was to determine the dose-rate effect of laser-generated ultrashort pulses of 4 MeV electron beam radiation on DNA damage and repair in human cells. The dose rate was increased via changing the pulse repetition frequency, without increasing the electron energy. The human chronic myeloid leukemia K-562 cell line was used to estimate the DNA damage and repair after irradiation, via the comet assay. A distribution analysis of the DNA damage was performed. The same mean level of initial DNA damages was observed at low (3.6 Gy/min) and high (36 Gy/min) dose-rate irradiation. In the case of low-dose-rate irradiation, the detected DNA damages were completely repairable, whereas the high-dose-rate irradiation demonstrated a lower l...

Research paper thumbnail of Effect of N-acetyl-L-cysteine on human chronic myeloid leukemia cells KCL22 treated with mitomycin C

Journal of Ecology and Environment, 2014

The effectiveness of N-acetyl-L-cysteine (NAC) to protect blood cells against Mitomycin C (MMC) i... more The effectiveness of N-acetyl-L-cysteine (NAC) to protect blood cells against Mitomycin C (MMC) induced genotoxicity was investigated in human chronic myeloid leukemia cells (KCL22) using the alkaline comet assay. The comet assay was selected as sensitive and rapid method for analysis of DNA damage and repair in individual cells. NAC treatment alone did not produce any damage in KCL22 cell. But NAC was found to be effective in reducing genotoxic damage in KCL22 cells exposed to MMC. These results confirm the literature data that, given the safety and ability to reduce DNA damage. NAC may be useful to prevent drug-mediated genotoxicity.

Research paper thumbnail of Comet-FISH

Springer Protocols Handbooks, 2016

Research paper thumbnail of Micronucleus FISH

Springer Protocols Handbooks, 2016

Research paper thumbnail of Comparative analysis of individual chromosome involvement in micronuclei induced by mitomycin C and bleomycin in human leukocytes

Molecular Cytogenetics, 2016

Background: Micronucleus (MN) assay is a well standardized approach for evaluation of clastogenic... more Background: Micronucleus (MN) assay is a well standardized approach for evaluation of clastogenic/aneugenic effects of mutagens. Fluorescence in situ hybridization (FISH) is successfully used to characterize the chromosomal content of MN. However, the relationships between nuclear positioning, length, and gene density of individual chromosomes and their involvement in MN induced by different mutagens have not been clearly defined. Results: Chromosomal content of MN was characterized in human leukocytes treated with mitomycin C (MMC) and bleomycin (BLM) by FISH using centromeric (cep) and whole-chromosome painting (wcp) probes. Involvement of chromosomes 8, 15 and 20 in MMC-induced and chromosomes 1, 9 and 16 in BLM-induced MN was studied, and correlated with chromosome size, gene density and interphase position. The results obtained were analyzed together with previous own data on the frequencies of inclusion of chromosomes 3, 4, 6, 7, 9, 16, 17, 18, and X in MMC-induced MN. It could be shown that MMC-and BLM-induced MN could contain material derived from all chromosomes investigated. Involvement of whole chromosomes 8, 15 and 20 in MMC-induced MN negatively correlated with gene density; however, analysis together with earlier studied chromosomes did not confirm this correlation. Inclusion of chromosomes 8, 15 and 20 in MMC-induced MN does not depend on their size and interphase position; the same result was found for the twelve overall analyzed chromosomes. In BLM-treated cells significant correlation between frequencies of involvement of chromosomes 1, 9 and 16 in MN and their size was found. Conclusions: Our results clearly revealed that BLM differs from MMC with respect to the distribution of induced chromosome damage and MN formation. Thus, DNA-damaging agents with diverse mechanism of action induce qualitatively different MN with regard to their chromosomal composition. Also this study demonstrates the utility of combined sequential application of cep and wcp probes for efficient detection of MN chromosomal content in terms of centric and acentric fragments.

Research paper thumbnail of Genotoxicity of Water Contaminants from the Basin of Lake Sevan, Armenia Evaluated by the Comet Assay in Gibel Carp (Carassius auratus gibelio) and Tradescantia Bioassays

Bulletin of Environmental Contamination and Toxicology, 2016

Combination of bioassays and chemical analysis was applied to determine the genotoxic/mutagenic c... more Combination of bioassays and chemical analysis was applied to determine the genotoxic/mutagenic contamination in four different sites of the basin of Lake Sevan in Armenia. Water genotoxicity was evaluated using the single cell gel electrophoresis technique (comet assay) in erythrocytes of gibel carp (Carassius auratus gibelio), Tradescantia micronucleus (Trad-MCN) and Tradescantia stamen hair mutation (Trad-SHM) assays. Significant inter-site differences in the levels of water genotoxicity according to fish and Trad-MCN bioassays have been revealed. Two groups of locations with lower (south-southwest of the village Shorzha and Peninsula of Lake Sevan) and higher (estuaries of Gavaraget and Dzknaget rivers) levels of water genotoxicity were distinguished. Correlation analysis support the hypothesis that the observed genetic alterations in fish and plant may be a manifestation of the effects of water contamination by nitrate ions, Si, Al, Fe, Mn and Cu. Increase of DNA damage in fish also correlated with content of total phosphorus.

Research paper thumbnail of Ruben M. Arutyunyan, Tamara F. Sarkisyan, Galina G. Oganesyan, Andrei D. Durnev Comparative investigation of anticlastogenic effects in cell cultures of healthy donors and patients with nettle-rash Mutation Research 1994 Mar;320(4):335-41

Mutation Research/Genetic Toxicology

In cultures of lymphocytes from 12 healthy donors and 12 patients with nettle-rash (NR) the antic... more In cultures of lymphocytes from 12 healthy donors and 12 patients with nettle-rash (NR) the anticlastogenic effect of the antimutagens WR-2721 (WR), bemitil (BM), tomerzol (TM) and interferon (IF) on the induction of chromosomal aberrations by photrin (PT) and dioxidine (DX) was investigated. There were no statistically significant differences between healthy donors and patients with NR in the levels of chromosomal aberrations that were spontaneous or induced by PT or DX. Statistically significant protective effects of BM, WR, TM and IF were demonstrated in cells of healthy donors after treatment with PT or DX, and after modification of the clastogenic action of PT in lymphocytes of NR patients.There was no protective effect of any of the anticlastogens after treatment of the lymphocyte cultures from NR patients with DX. That observation allows us to suggest the test of anticlastogenic action as a measure of sensitivity of the chromosomal apparatus in groups with different genetic r...

Research paper thumbnail of A New Case of a Complex Small Supernumerary Marker Chromosome: A Der(9)t(7;9)(p22;q22) due to a Maternal Balanced Rearrangement

Journal of Pediatric Genetics, 2015

Complex small supernumerary marker chromosomes (sSMCs) constitute one of the smallest subsets wit... more Complex small supernumerary marker chromosomes (sSMCs) constitute one of the smallest subsets within the patients with an sSMC. Complex sSMCs consist of chromosomal material derived from more than one chromosome, for example, the derivative der(22)t(11;22)(q23;q11.2) in Emanuel syndrome. Here, a yet unreported case of a complex sSMC formed due to a t(7;9)(p22;q22)mat is presented.

Research paper thumbnail of Comet-assay in combination with PNA-FISH detects mutagen-induced DNA damage and specific repeat sequences in the damaged DNA of transformed cells

International journal of molecular medicine, 2005

The Comet-assay was applied to three transformed cell lines (HT1080, CCRF-CEM line and CHO) which... more The Comet-assay was applied to three transformed cell lines (HT1080, CCRF-CEM line and CHO) which were treated with the cytostatics bleomycin (BLM) or mitomycin C (MMC). In addition, PNA probes for the telomere repeat (TTAGGG)(n) were used for detection of telomeric DNA sequences in the damaged DNA. Data were compared with previously obtained results from peripheral leukocytes. The amount of migrating DNA increased in all cell types in a dose-dependent manner after BLM exposure. CHO cells reacted sensitively at low doses of the mutagen, and leukocytes had the highest dose-related effect up to 25 IU/ml which, however, did not further increase. A rather linear dose response characterized the HT1080 cells, the effect was lowest for the CCRF-CEM cells. While MMC at lower doses increased the percentage of migrating DNA in a dose-dependent manner, the higher doses induced shorter comets, on average, than the lower ones in all cell lines. With PNA-Comet-FISH obvious differences were found ...

Research paper thumbnail of Combined Genotoxic Effects of Aflatoxin B1, Ochratoxin A and Zearalenone in Rat Bone Marrow and Blood Leukocytes

Mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA) are widespread ... more Mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA)
are widespread contaminants of food and feedstuffs. It is very likely, that humans and animals
are always exposed to mixtures of mycotoxins rather than to individual compounds. Therefore,
risk assessments should consider mixture toxicity data. In the present study the combination of
AFB1, OTA and ZEA was tested for genotoxicity in rat bone marrow and blood leukocytes after
15, 30 and 60 days treatment. The level of DNA damage was determined by the comet assay. The
tail intensity and Olive tail moment in leukocytes and bone marrow cells were significantly higher
than in controls. At the same time, the level of DNA damage in bone marrow cells was higher than
in leukocytes. The data suggests that prolonged exposure to mycotoxins combination through
food consumption can induce DNA damage contributing to the harmful effects in vivo.

Research paper thumbnail of Fragility of telomeres after bleomycin and cisplatin combined treatment measured in human leukocytes with the Comet-FISH technique

Experimental oncology, 2005

THE AIM of the present study was the comparative investigation of action of widely applied antica... more THE AIM of the present study was the comparative investigation of action of widely applied anticancer preparations: cisplatin (cis-DDP) and bleomycin (BLM) on total DNA and telomeres damage in human blood cells. The "Comet-FISH technique" -- single cell gel electrophoresis ("comet assay") in combination with fluorescent in situ hybridization (FISH) was used for this purpose. This newly applied combined approach permits to detect on the same specimen the total DNA damage in individual cells and evaluate specific DNA sequences as well. Telomere -- specific -- PNA (peptide nucleic acid) probes were used for the localization of telomeres in the comet's head and their migration to the tail. THE RESULTS obtained indicate that in control variants, due to DNA metabolism and handling, approximately 7% of the DNA and 17% of the telomeres were found in the tail. In cells treated with BLM alone, telomeres leak out with equal probability as total DNA. In turn, the combina...

Research paper thumbnail of Evaluation of cisplatin-DNA crosslinks formation with UV-C application by the alkaline Comet-assay

Experimental oncology, 2004

The AIM of the present study was to investigate DNA damage induced by widely applied anticancer p... more The AIM of the present study was to investigate DNA damage induced by widely applied anticancer preparation cisplatin (cis-DDP) at doses comparable with therapeutic ones in leukocytes of healthy donors. DNA damage and repair was estimated by the single cell gel electrophoresis or Comet-assay. For estimation of cis-DDP-induced DNA crosslinks the combined treatment by cis-DDP with the DNA damaging agent UV-C was used. The RESULTS obtained indicate that cis-DDP is forming crosslinks with DNA in human leukocytes and significantly reduce UV-C-induced DNA migration. The Comet-assay with UV-C application is a useful tool to detect cis-DDP- induced DNA crosslinks. Data on the cis-DDP-induced DNA damage in vitro may be important for their extrapolation on in vivo level.

Research paper thumbnail of Butyrate reduces the frequency of micronuclei in human colon carcinoma cells in vitro

Toxicology in Vitro, 2009

Butyrate, formed by bacterial fermentation of plant foods, has been shown to protect human colon ... more Butyrate, formed by bacterial fermentation of plant foods, has been shown to protect human colon cells from selected genotoxic substances. The mechanism for this effect could be the enhancement of toxicological defence leading to an increased detoxification of genotoxic risk factors and thus to a reduction of DNA and chromosome damage. Previous protective properties of butyrate against DNA damage induction in colon cells were demonstrated using the comet assay. In the present study the effect of butyrate on chromosome damage induced by ferric nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H 2 O 2 ) (suggested to be putative risk factors of colorectal carcinogenesis) was investigated using the cytokinesisblock micronucleus (CBMN) test. It was possible to reveal that pre-treatment of HT29 colon carcinoma cells with butyrate (2 and 4 mM) for 15 min caused a reduction of micronuclei induced with H 2 O 2 (75 lM; p < 0.01) and Fe-NTA (500 and 1000 lM; p < 0.05). The decrease in the level of Fe-NTA-and H 2 O 2 -induced micronuclei was also confirmed in most of the corresponding variants of 24 h pre-treatment of cells with butyrate. The results obtained demonstrate for the first time protective properties of butyrate against chromosome damage induced by H 2 O 2 and Fe-NTA in human colon carcinoma cells.