• Environmental Mutagens and Carcinogens
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• v.10 no.1
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• pp.1-10
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• 1990

The regulation of DNA repair genes expression was investigated using fused genes, in which the promoter of repair genes was hybridized with the lacZ structural gene. The activities of beta-galactosidase expressed from the fused gense were highly increased when the host cells were exposed to methylating agents, such as methyl methansulfonate (MMS), N-methyl-N'-nitro-nitrosoguanidine (MNNG) and methyl nitrosourea (MNU). On the other hand, the enzyme activities from the fused genes were not induced when the cells were treated with ethylating or nonalkylating agents, such as ethyl methansulfonate (EMS), 4-nitroquinoline-1-oxide (4NQO), Bleomycin, and Benzo(a)pyrene (BP).

• Environmental Mutagens and Carcinogens
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• v.10 no.1
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• pp.25-32
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• 1990

포배단계의 북미산 표범개구리 Rana pipiens의 핵을 국내종 북방산개구리 Rana dybowskii의 무핵난에 이식하여 형성되는 nucleocytoplasmic hybrid 개체는 초기 낭배시기를 전후하여 치사하는 조합임이 핵치환 실험에 의하여 밝혀졌다. 이들의 치사원인이 이질세포질의 존재에 의한 일시적 현상인지 또는 발생도중 핵내에 일어난 영구적 변화에 의한 것인지를 조사하기 위한 노력의 일환으로 치사직전 개체의 염색체를 분석한 결과, 염색체의 수와 염색체의 일부분에 구조적 이상이 다양하게 관찰되었다. 따라서 이질세포질에서 DNA의 이상복제가 진행되었음을 나타내고 있으며 그 결과 비정상적 염색체를 가진 할구의 형성과 부분 난할등이 유발되어 결국 치사하는 것으로 사료된다. 또한 nuclocytoplasmic 개체의 lethality 는 정상개체와의 접촉에 의해 교정되지 않는 조직의 내적 특성임이 hybrid의 조직을 정상 embryo로 이식시킨 실험을 통해 명확히 밝혀졌다.

• Environmental Mutagens and Carcinogens
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• v.10 no.1
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• pp.11-24
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• 1990

발생중인 계배의 날개에서 지골의 복제를 유발하는 retinoic acid(RA)가 날개의 조직발생에 미치는 영향을 알아보았다. Hamburger와 Hamilton stage 19에 도달한 계배의 wingbud 앞부분에 RA를 처리하고 처리후 24, 48, 72시간이 경과되었을 때 나타난 조직상의 변화를 조사하여 다음과 같은 결과를 얻었다. (1) RA처리는 처리부위와 인접한 조직에서 세포밀도의 감소를 초래하였으며 처리부위와 떨어진 부위에서는 오히려 세포밀도의 증가를 유발하였다. (2)RA처리는 apical ectodermal ridge(AER) 길이의 신장을 유발하였고 또한 그 위치의 전단부 쪽으로의 이동을 가져왔다. (3) 이러한 조직상의 변화는 처리후 24시간에 나타나 72시간까지 계속 되었으며, 특히 처리후 72시간에는 날개의 앞부분에서 원래의 AER외에 복제된 AER을 관찰할 수 있었다. 이러한 RA처리에 다른 조직상에서의 변화는 RA처리에 의하여 유발되는 지골복제현상이 처리후 24시간내에 시작되는 중배엽성조직 및 중배엽조직의 성장과 분화에 필수적인 AER의 변화에 기인함을 시사하고 있다.

• Environmental Mutagens and Carcinogens
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• v.22 no.4
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• pp.255-258
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• 2002

In order to determine the safety of chemicals and pharmaceutical products, various methods can be used to evaluate the toxicity. In this study the genotoxic effect of the widely used industrial chemical, cadmium chloride, was assessed using the micronucleus test in peripheral blood of mice. The presence of micronucleated reticulocytes by microscopic observation following acridine orange staining indicated a potential genotoxic effect. The genotoxicity of intraperitoneally (i.p.) administered cadmium chloride (0.5, 1, 2 mg/kg) appeared to be dose dependent, with the maximum tolerated dose (MTD) found to be 2 mg/kg. Compared to the negative control (saline), cadmium chloride (2 mg/kg) exhibited statistically significant genotoxic potential (P<0.05) but was found to be less than the positive control of mitomycin C (0.5 mg/kg) and was not statistically significant compared to historical negative controls (P>0.05).

• Environmental Mutagens and Carcinogens
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• v.22 no.4
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• pp.279-288
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• 2002

According to the epidemiological studies in chromium workers, hexavalent chromium is associated with the risk of lung cancer. Cellular oxidative damages by reactive oxygen species produced by hexavalent chromium exposure may play an important role in the carcinogenesis process. We investigated the availabilities of malondialdehyde measurement for the assessments of oxidative damages from chromium exposure with an experimental inhalation study in vivo. Lipid peroxidation, one kind of cellular oxidative damage, was measured in blood plasma of the rats which inhaled the hexavalent chromium mist for 1, 2 and 3 weeks. The concentrations of malondialdehyde (MDA), the metabolite of lipid peroxidation, in all exposed groups were higher than those of controls with dose-dependant manner. The levels of MDA were also correlated with urine chromium levels of the rats. Therefore, MDA as an indicator of lipid peroxidation could be proper biologic marker for the assessment of the oxidative damage from chromium exposure, which might be involved in carcinogenesis.

• Environmental Mutagens and Carcinogens
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• v.18 no.1
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• pp.9-14
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• 1998

By far, the largest known preventable cause of cancer is cigarette smoking. The percentage of cancer deaths in Korea due to tobacco is still increasing. Smoking cigarette at an early age has become more common among women. Tobacco consumption is related causally to cancer to the lung, mouth, larynx, esophagus, bladder, kidney, uterine cervix, and pancreas. Recently, several studies demonstrated that there is very strong correlation between cigarette smoking and p53 mutations in lung cancer, head and neck cancer, and bladder cancer. The recent findings of cigarette smoking and cancer, p53 and bcl-2 mutations, adverse effects of smoking on the effects of radiotherapy, and benefits of quitting will be discussed.

• Environmental Mutagens and Carcinogens
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• v.26 no.3
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• pp.86-88
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• 2006

Cytochrome P450 1A2 (CYP1A2) is a xenobiotic metabolizing enzyme that is tissue-specifically expressed in the mammalian liver. In this study, the extent of CYP1A2 promoter methylation was analyzed to determine its potential role in the regulation of CYP1A2 in diethylnitrosamine (DEN)-induced mouse liver tumors. CYP1A2 mRNA was under-expressed about three fold in DEN-induced liver tumors compared to age-matched control livers. The CYP1A2 promoter was hypermethylated in DEN-induced liver tumors compared to controls, especially in a promoter domain close to the coding region. These results suggest that promoter methylation is involved in the regulation of CYP1A2 in mouse liver tumors.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.99-103
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• 2003

An Escherichia coli strain containing the recA promoter that fused to the luxCDABE operon originating from Photorhabdus luminescens was shown to respond sensitively to genotoxic stresses. Two different recombinant bacteria, one (DPDI 657) harboring a plasmid with the recA promoter that fused to the luxCDABE operon, and the other (DPD1710) containing a chromosomally-integrated recA promoter that fused with luxCDABE, were compared and it was found that the sensitivity of 'the two strains was significantly different in terms of their bioluminescent level, response time, and the minimum detectable concentration of a chemical causing DNA damaging stress. DPDI 710, with a chromosomally-integrated single copy, generally led to lower basal luminescence levels, faster responses, increased response ratios, and an enhanced sensitivity to mutagens, when compared to DPD 1657 with a multi-copy plasmid.

• Environmental Mutagens and Carcinogens
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• v.25 no.2
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• pp.71-75
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• 2005

Green tea and their major constituents such as catechins are famous materials for their anti-oxidative and anti-carcinogenic activity, but many compounds with reducing power can promote the oxidation in their oxidized form or in the presence of metal ion. We investigated the pro-oxidative effect of the ethanol extract equivalent up to 30mg of dried weight of green tea leaves in four in vitro systems which could be used for detecting DNA damage. Although ethanol extract of green tea did not show significant mutagenicity in Salmonella typhimurium TA102, which is sensitive strain to oxidative stress, it degraded deoxyribose extensively in the presence of $FeCl_3-EDTA$ complex, promoted 8-oxoguanine formation in the live bacteria cell, Salmonella typhimurium TAI04, and cleaved super coiled DNA strand with the help of copper ion. It suggested that green tea, famous anti-oxidative material, can be pro-oxidant according to the condition of extraction or metal existence.

• Environmental Mutagens and Carcinogens
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• v.19 no.2
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• pp.102-107
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• 1999

A population monitoring studies for assessing the genotoxicity of occupationally exposed mixed organic solvents to printers were performed by using the chromosome aberration assay and the cytokinesis-blocked micronucleus assay. The incidence of chromosome aberrations and micronuclei was studied in the peripheral blood lymphocytes of 51 male printers and their matched controls in Seoul area. Smoking habits and duration of employment were taken into account. The frequencies of micronucleus in peripheral lymphocytes of printers were significantly different in comparision with control subjects. Also there were significant increase in the frequencies of micronucleus by duration of exposure. The frequencies of chromosome aberrations showed no significant differences between printers and their matched controls.