• Environmental Mutagens and Carcinogens
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• v.7 no.2
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• pp.103-111
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• 1987

The effects of LET (linear energy transfer) of radiation on the induction of somatic chromosome mutations or gene mutations of Drosophila melanogaster were studied. For detecting somatic chromosome mutations and gene mutations, Drosophila wing spot system and eye-color spot system were used, respectively. The frequencies of somatic chromosome mutations or gene mutations induced after third instar larval treatment with 23 MeV neutrons, thermal neutrons, X-rays were examined. From these data, the RBE(relative biological effectiveness) values of 23 MeV neutrons relative to X-rays for induction of somatic chromosome mutations or gene mutations were calculated. The present results suggest that high LET radiations are efficient than X-ray in producing not only somatic chromosome mutations but also gene mutations.

• Environmental Mutagens and Carcinogens
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• v.15 no.2
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• pp.100-105
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• 1995

The effects of DNA polymerase $\beta$ on the somatic chromosome mutations and mitotic recombinations were investigated using the transgenic Drosophila beating chimetic gene consisting of a promoter region of Drosophila actin 5C gene and rat DNA polymerase $\beta$. For detecting the somatic chromosome mutations and mitotic recombinations, the heterozygous (mwh/+) strains possessing or lacking transgene poi 13 were used. The spontaneous frequency of small mwh spots, due to deletion or nondisjunction etc., in the non-transgenic w strain and the transgenic p[pol $\beta$]-130 strain was 0.351 and 0.606, respectively. The spontaneous frequency (0.063) of large mwh spots, arises mostly from somatic recombination between the centromere and the locus mwh, in the transgenic p[pol $\beta$]-130 strain was about three times higher than that (0.021) of the non-transgenic w strain. The mutant clone frequencies of small and large mwh spots induced by N-methyl-N'-nitro-N-nitrosoguanidine and ethyl methanesulfonate in the transformant p[pol $\beta$]-130 were higher than those in the host strain w. The present results suggest that rat DNA polymerase $\beta$ participate at least in the somatic chromosome mutations and mitotic recombination processes.

• Korean journal of applied entomology
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• v.35 no.4
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• pp.315-320
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• 1996

The effects of 2-arnino-3-methyIimidazo[4,5-fq]u inoline (IQ), 2-amino-6dimethyl-dipyrido[l,2-a;3',2'-d] imidazole (Glu-P-1) and aflatoxin B1 (AFBI) on the mitotic recombinations and somatic chromosome mutations were investigated using the transgenic Drosophila bearing a chimeric gene consisting of a promoter region of Drosophila actin 5C gene and rat DNA polymerase $. For investigating mitotic recombinations and the somatic chromosome mutations, the heterozygous (mwhl+) strain possessing or lacking transgene pol P was used. The spontaneous frequency of small mwh spots, due to deletion or nondisjunction etc., in the non-transgenic w strain and the transgenic plpol $1-130 strain was 0.351 and 0.606, respectively. The spontaneous frequency (0.063) of large mwh spots, arising mostly from somatic recombination between the centromere and the locus mwh, in the transgenic plpol $1-130 strain, was about three times higher than that (0.021) of the non-transgenic w strain. The mutant clone frequencies of two types induced by two heterocyclic mines (IQ and Glu-P-1) and AFBl in the transformant pbol PI-130 were two or three times higher than those in the host strain w. These mean that rat DNA polymerase P participates at least in the somatic chromosome mutations and mitotic recombination processes. And the present results suggest that the transgenic Drosophl!~ used in this study can be used as a hypersensitive, in vivo short-term assaying system for various environmental mutagens.

• BMB Reports
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• v.51 no.9
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• pp.437-443
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• 2018

Non-homologous end joining (NHEJ), and to a lesser extent, the error-free pathway known as homology-directed repair (HDR) are cellular mechanisms for recovery from double-strand DNA breaks (DSB) induced by RNA-guided programmable nuclease CRISPR/Cas. Since NHEJ is equivalent to using a duck tape to stick two pieces of metals together, the outcome of this repair mechanism is prone to error. Any out-of-frame mutations or premature stop codons resulting from NHEJ repair mechanism are extremely handy for loss-of-function studies. Substitution of a mutation on the genome with the correct exogenous repair DNA requires coordination via an error-free HDR, for targeted transgenesis. However, several practical limitations exist in harnessing the potential of HDR to replace a faulty mutation for therapeutic purposes in all cell types and more so in somatic cells. In germ cells after the DSB, copying occurs from the homologous chromosome, which increases the chances of incorporation of exogenous DNA with some degree of homology into the genome compared with somatic cells where copying from the identical sister chromatid is always preferred. This review summarizes several strategies that have been implemented to increase the frequency of HDR with a focus on somatic cells. It also highlights the limitations of this technology in gene therapy and suggests specific solutions to circumvent those barriers.

• YAKHAK HOEJI
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• v.38 no.3
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• pp.332-337
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• 1994

Using germinal and somatic cell mutation assaying systems of Drosophila melanogaster, effects of Ginseng and Salvia miltiorrhiza extracts on the in vivo mutagenicity induced by N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) were investigated. For these purpose, the attached-X method and the mwh/flr spot test system which are an X-linked lethal mutation and a somatic chromosome mutation assaying system, respectively, were used. In the induction of X-linked lethal mutations during the spermatogenesis, MNNG showed more actions in the sperm and spermatid stages, in which Ginseng and Salvia miltiorrhiza extracts had remarkable inhibitory effects than other stages. Ginseng and Salvia miltiorrhiza extracts reduced the mutagenicity by MNNG in the mwh/flr system, which reveal that they can inhibit gene mutation, deletion and mitotic chromosomal recombination. These results seem to suggest that Ginseng and Salvia miltiorrhiza extracts may exert their inhibitory effects to in vivo mutagenic and/or carcinogenic properties of DNA-damaging agents.

• Journal of Environmental Science International
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• v.8 no.5
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• pp.569-574
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• 1999

This study was carried out to determine the antimutagenic effects of genistein on the somatic mutagenicity induced by aflatoxin B1 (${AFB}_1$), using Drosophila wing spot test system. Mutagen alone or mutagen with genistein were administered to the heterozygous(mwh/+) third instar larvae by feeding, and somatic cell mutations were detected in adult fly wing hairs. Genistein did not show any mutagenicity with the feeding concentrations of 5~15% in the test system. As the feeding concentrations of genistein increased, genistein inhibited the mutagenicity induced by AFB1 (14.6%~62.2% inhibition rate), while as the concentrations of AFB1 increased, small much spots that arise mostly from chromosome deletion and nondisjunction were more strongly suppressed by genistein than the large mwh spots from chromosomal recombination. In each group of different AFB1 concentrations, the rate of inhibition for total mwh spots was dependent on the dose of genistein. These results indicate that genistein have inhibitory effect on the mutagenicity induced by a mtagen, ${AFB}_1$. It seems to suggest that genistein may exert inhibitory effects to mutagenic and/or carcinogenic properties of DNA damaging agents.

• Biomolecules & Therapeutics
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• v.6 no.1
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• pp.63-72
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• 1998

-4-Quinolone antibiotics (pefloxacin, ciprofloxacin, norfoxacin, ofloxacin and enoxacin) were tested for mutagenicity in Salmonella typhimurium TA98, TA100, TA1535, TA1537, TA1538 and TA102, for chromosomal aberrations in cultured Chinese hamster lung (CHL) cells, and for wing somatic mutations and recombinations (wing spot) in Drosophila. Five 4-quinolones did not show any mutagenicity in Salmonella typhimurium TA98, TA100, TA1535, TA1537 and TA1538. However, they were mutagenic inSalmonella typhimurium TA102 with and without metabolic activation in both plate incorporation method and preincubation method. Ciprofloxacin induced structural chromosome aberrations in CHL cells both with and without metabolic activation, and the frequencies were 6% and up to 28%, respectively. Pefloxacin showed equivocal evidence, however, norfloxacin, ofloxacin and enoxacin did not induce the structural chromosome aberrations both in the presence and absence of metabolic activation. In the wing spot assay in Drosophila, ofloxacin increased the frequency of small single spots significantly in a dose-dependent manner but there was no dose-dependent increase of single or twin spots in the others.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2004.05a
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• pp.47-60
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• 2004

Higher plants can be valuable genetic assay systems for monitoring environmental pollutants and evaluating their biological toxicity. Two assays are considered ideal for in situ monitoring and testing of soil, airborne and aqueous mutagenic agents; the Tradescantia stamen hair assay for somatic cell mutations and the Tradescantia micronucleus assay for chromosome aberrations. Both assays can be used for in vivo and in vitro testing of mutagens. Since higher plant systems are now recognized as excellent indicators and have unique advantages over in situ monitoring and screening, higher plant systems could be accepted by regulatory authorities as an alternative first-tier assay system for the detection of possible genetic damages resulting from the pollutants or chemicals used and produced by industrial sectors. It has been concluded that potential mutagen and carcinogen such as the heavy metals among indoor air particulates, volatile compounds in the working places, soil, and water pollutants contribute to the overall health risk. This contribution can be considerable under certain circumstances. It is therefore important to identify the level of genotoxic activity in the environment and to relate it to the biomarkers of a health risk in humans. The results from the higher plant bioassays could make a significant contribution to assessing the risks of pollutants and protecting the public from agents that can cause mutation and/or cancer. The plant bioassays, which are relatively inexpensive and easy to handle, are recommended for the scientists who are interested in monitoring pollutants and evaluating their environmental toxicity to living organisms.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2004.05a
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• pp.1-15
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• 2004

Higher plants can be valuable genetic assay systems for monitoring environmental pollutants and evaluating their biological toxicity. Two assays are considered ideal for in situ monitoring and testing of soil, airborne and aqueous mutagenic agents; the Tradescantia stamen hair assay for somatic cell mutations and the Tradescantia micronucleus assay for chromosome aberrations. Both assays can be used for in vivo and in vitro testing of mutagens. Since higher plant systems are now recognized as excellent indicators and have unique advantages over in situ monitoring and screening, higher plant systems could be accepted by regulatory authorities as an alternative first-tier assay system for the detection of possible genetic damages resulting from the pollutants or chemicals used and produced by industrial sectors. It has been concluded that potential mutagen and carcinogen such as the heavy metals among indoor air particulates, volatile compounds in the working places, soil, and water pollutants contribute to the overall health risk. This contribution can be considerable under certain circumstances. It is therefore important to identify the level of genotoxic activity in the environment and to relate it to the biomarkers of a health risk in humans. The results from the higher plant bioassays could make a significant contribution to assessing the risks of pollutants and protecting the public firom agents that can cause mutation anuor cancer. The plant bioassays, which are relatively inexpensive and easy to handle, are recommended for the scientists who are interested in monitoring pollutants and evaluating their environmental toxicity to living organisms.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.373-378
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• 2011

Our aim was to investigate the genotoxicity of ambient air in the Krak$\acute{o}$w area after Fukushima Nuclear Power Plant (NPP) accident and compare with results from Chernobyl fallout. For the detection of ambient air genotoxicity the technique for screening gene mutation frequency in somatic cells of the $Tradescantia$ stamen hairs ($Trad$-SH assay) was used. Since 11th of March 2011 (Fukushima NPP accident), several pots containing at least 15 shoots of bioindicating plants were exposed to ambient air at 2 sites in the Krak$\acute{o}$w surrounding area, one in the city center, and about 100 pots in a control site (in the glasshouse of the Institute of Nuclear Physics) Continuous screening of mutations was performed. Progenies of 371,090 cells exposed were analyzed. Mutation frequency obtained in the first 10 days has shown a mean control level (GMF*100=$0.06{\pm}0.01$). At scoring period related to influence of a potential Fukushima fallout, a significant increase of gene mutation frequencies above the control level was observed at each site in the range, 0.10~0.33 depending on the location, (mean value for all sites GMF*100=$0.19{\pm}0.05$) that was associated with a strong expression of toxic effects. In the reported studies following the Chernobyl NPP accident monitoring $in$ $situ$ of the ambient air genotoxicity was performed in the period since April $29^{th}$ till June $3^{rd}$ 1986 also with Trad-SH bioindicator. In general, mutation frequency increases due to Chernobyl fallout(GMF*100=$0.43{\pm}0.02$) were corresponding to fluctuation of radioactivity in the air reported from physical measures, and to published reports about increase in chromosome aberration levels. Although, recent data obtained from monitoring of the ambient air quality in the Krak$\acute{o}$w and surroundings are lower when compared to results reported after Chernobyl NPP accident, though results express a significant increase above the control level and also are corresponding with increased air radioactivity reported from physical measurements. Statistically significant in comparison to control increase in gene mutation rates and more prolonged than that after Chernobyl fallout increase of GMF was observed during the period following the Fukushima NPP failure.