• Environmental Engineering Research
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• 제18권3호
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• pp.139-143
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• 2013

This study was performed to examine the in vitro toxicities which are incurred due to the mobilization metals from standard reference material (SRM) 1648, fine ($PM_{2.5}$), and coarse ($PM_{10}$) particulate matter collected in Seoul metropolitan area. DNA single strand breaks of approximately 74% and 62% for $PM_{2.5}$ and for $PM_{10}$, respectively, were observed in the presence of chelator (EDTA or citrate)/reductant (ascorbate), as compared to the control by 2% without chelator or reductant. $PM_{2.5}$ induced about 40% more carbonyl formation with proteins in the presence of EDTA/ascorbate than $PM_{10}$. Therefore, more damage to biomolecules was incurred upon exposure to $PM_{2.5}$ than to $PM_{10}$. The treatment of a specific chelator, desferrioxamine, to the reaction mixture containing chelator plus reductant decreased the extent of damage to DNA to the level of the control, but did not substantially decrease the extent of damage to proteins. This suggests that different arrays of metals were involved in the oxidation of DNA and proteins.

• 환경생물
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• 제22권4호
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• pp.507-512
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• 2004

This study was focused on the risk assessment of whether radiofrequency electromagnetic fields generated by mobile phone is cytogenetically toxic or not. We conducted the effects of 835-MHz electromagnetic field (EMF) on DNA strand breaks in mouse thymic lymphoma L5178Y $Tk^{+/1-}$ cells using alkaline comet assay. EMF frequency 835-MHz we chosen is one of the most popular communication frequency bands in Korean code-division multiple-access (CDMA) mobile phone system. The cells were exposed to 835-MHz EMF alone or 835-MHz EMF combined with cyclophosamide(CPA) or 4-nitroquinoline-1-oxide (4NQO) at specific absorption rate (SAR) of 4.0 W $kg^{-l}$ for 24 and 48hrs. DNA damage expressed as tail moment was increased more than two-fold after exposure to 835-MHz EMF for 24 and 48hr. In particular, CPA for 48hr and 4NQO for 24 hr enhanced notably the tail moment to 9-fold and 16-fold in the presence of 835-MHz EMF, respectively, compared to each single treatment. From these results, it appears that exposure to CDMA-mobile phone radiation at 835-MHz frequency may potentiate DNA strand breaks of mouse thymic lymphoma L5178Y $Tk^{+/1-}$;cells under the defined conditions of this study.

• 미생물학회지
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• 제49권1호
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• pp.1-7
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• 2013

유전자 재조합체는 상동염색체간의 예정된 DNA 가닥 전이와 교환이 이루어지는 상동염색체 재조합 과정에 의하여 생성된다. 이 재조합 경로는 DNA 이중 가닥 절단(double-strand breaks, DSBs)에 의해서 개시되며, 전이 과정의 중간단계에서 DNA의 구조적 변이 중간체인 단일 가닥 침투(single-end invasions, SEIs)와 이중 홀리데이 접합(double-Holliday junctions, dHJs)이 형성되어 교차성(crossover, CO) 혹은 비교차성(non-crossover, NCO) 결과물이 만들어진다. 본 연구는 이중 가닥 절단, 단일 가닥 침투, 이중 홀리데이 접합과 같은 재조합 중간체와 재조합 결과물의 구조분석에 초점을 두고, 이를 출아효모에서 인위적으로 이중 가닥 절단을 발생시킬 수 있는 HIS4LEU2 "hot spot" 을 이용한 물리적 분석방법으로 감수분열 재조합 중간체를 규명하였다. 물리적 분석을 위하여 동조화 된 세포에 감수분열을 유도한 후 hot spot 자리를 인식하는 제한효소를 처리하면, 재조합 중간체를 형성하고 있는 DNA 단편들을 Southern 분석법을 통해 탐지 및 정량 할 수 있다. 본 연구는 이 시스템으로 감수분열에서 이중가닥 절단으로부터 기인하는 단일 가닥 침투, 이중 홀리데이 접합 그리고 교차성/비교차성 재조합체로 전이되는 DNA의 구조 다형을 분석할 수 있음을 제시한다.

• 한국양식학회지
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• 제16권3호
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• pp.196-201
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• 2003

Sessile organisms such as the oyster Crassostrea gigas have been given much attention as a potential biomonitoring indicator to assess the impact of toxicants on aquatic organism. In this study, we exposed cells isolated from gill of oyster (Crassostrea gigas) to hydrogen peroxide in vitro. In addition oysters were in vivo exposed to pyrene and benzo(a)pyrene at various concentrations for 2 weeks. Comet assay was used to detect DNA single strand breaks and to investigate the application of this technique as a tool for aquatic biomonitoring. Hydrogen peroxide increased DNA single strand break with increasing concentration after 30 minutes exposure in vitro. Pyrene and benzo(a)pyrene caused DNA damage only at very high concentration (100 $\mu\textrm{g}$/L or 1000 $\mu\textrm{g}$/L) at two week exposure in vivo. DNA damage was relatively higher at hemocyte than at gill. It suggested that metabolized PAHs are transferred to hemolymph from digestive gland which have a relatively high enzyme activity, and attacked the DNA of hemocyte, while gill accumulated PAHs without degrading them to their metabolites due to low enzyme activity at gill. Both in vitro and in vivo exposure experiments showed that the comet assay is an effective tool on screening whether the organism are exposed to genotoxic contaminants.

• 한국환경성돌연변이발암원학회지
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• 제8권1호
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• pp.1-12
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• 1988

본 연구는 Ethyl methanesulfonato(EMS) 혹은 Bleomycin(BLM)에 의해 유발된 DNA상해의 회복에 미치는 DNA 종합효소 $\alpha$ 저해제인 Aphidicolin(APC)과 DNA 종합효소 $\beta$의 저해제인 2`, 3`-dideoxythymididine 5`-triphosphate(ddTTP)의 영향을 조사하기 위하여 Chinese hamster ovary(CHO)-Kl 세포를 재료로 비주기성 DNA 합성법과 알칼리유출법 및 스칼리 자당구배침강법으로 수행하여 얻은 결과는 다음과 같다. APC와 ddTTP는 EMS에 의해 유발된 DNA 상해의 회복을 저해하여 APC 혹은 ddTTP를 처리하지 않고 배양한 실험군 보다 비주기성 DNA 합성율과 DNA 단사 절단율이 증가되었다. 한편 BLM에 의해 유발된 DNA 상해의 회복에서는 ddTTP를 처리했을 경우에만 저해되었다. 즉 BLM 처리 후 ddTTP를 후처리한 실험군의 비주기성 DNA 합성율과 DNA단사 절단율은 ddTTP를 처리하지 않은 군보다 증가되었고, BLM 처리 후 APC를 후처리할 경우에 비주기성 DNA 합성율과 DNA 단사 절단율은 APC를 처리하지 않은 군과 유사하였다. 이상의 결과들에서 EMS에 의해 유발된 DNA 상해의 회복에는 DNA 중합효소 $\alpha$, $\beta$양자가 관여하나 BLM에 의해 유발된 DNA 상해의 회복에는 중합효소 $\beta$가 관여하는 것으로 추측된다.

• 한국환경과학회지
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• 제14권11호
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• pp.1071-1079
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• 2005

Using single cell gel electrophoresis, DNA single strand breaks were determined in various marine organisms. DNA damage on fish blood cells was detected to know whether there was a difference between Incheon, Pohang, Masan, and Tongyeong as a control site. Tongyeong showed the lowest DNA damage among the study areas. Mussels, transplanted to Masan Bay for one month, revealed high DNA damage at sites with high economical activity. In two weeks exposure of polychaete to Incheon sediments, higher DNA damage was detected in the sediment adjacent to Incheon harbor than open sea. These results suggested that the marine organism from the polluted area revealed a relatively high DNA damage. In addition, these areas might be contaminated with genotoxic compounds and comet assay was useful as a bioassay to detect DNA damage in marine organisms.

• 약학회지
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• 제51권4호
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• pp.239-245
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• 2007

In order to evaluate the genotoxicity of airborne particulate matter extracted with dichloromethane (APE), the rat microsome mediated (S-9) or DNA repair enzyme treated Comet assays were performed using the single cell gel electrophoresis in A549 human lung carcinoma cells. It was found that the cells interacting with APE showed more DNA single-strand breaks relative to untreated cells. The genotoxicity of APE was increased with the treatment of S-9 mixture. Microsome mediated DNA damage was inhibited by CYP1Al inhibitor, quercetin. The APE also showed oxidative DNA damage evaluated by endonuclease III treatment. Oxidative DNA damage of APE was inhibited by antioxidants such as vita- min C and Trolox. We also found that the vegetables or fruits extract may reduce APE-induced genotoxicity by their anti- oxidant activity and CYP1A1 inhibition.

• Journal of Radiation Protection and Research
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• 제24권2호
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• pp.93-99
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• 1999

Alkaline single cell gel electrophoresis (SCGE) assay는 일명 혜성분석이라고 부르며 in vivo 와 in vitro 에서 많은 화학적, 생물학적인 인자에 의한 DNA 손상을 감지하는데 유용한 기법으로 각각의 세포에서 DNA 단일 가닥 절단과 알칼리에 약한 장소를 평가하는 새로운 방법으로 인정되고 있다. 단세포 겔 전기영동법 (SCGE)을 사용하여 복숭아씨 추출물이 방사선에 의하여 사람 림프구 DNA에 나타나는 손상을 보호하는 지 여부를 평가하였다. 복숭아씨 추출물로 10 분간 전처리한 림프구를 0, 0.1, 0.3, 0.5, 1.0, 2.0 Gy 의 방사선으로 조사하였고 방사선만을 조사한 림프구 실험군과 비교평가하였다. 혜성분석에서 DNA 가닥 절단에 대한 표식인 tail moment의 증가는 감마선에 대해서 뚜렷한 선량-반응 관계를 나타내었으며 각각의 농도별로 복숭아씨 추출물이 처리된 림프구의 DNA 손상은 현저히 감소하였다. 단세포 겔 전기영동법을 통한 평가결과 복숭아씨 추출물은 방사선에 의한 림프구 DNA 손상에 대한 탁월한 방어효과를 나타내었다.

• The Korean Journal of Physiology and Pharmacology
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• 제8권2호
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• pp.95-100
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• 2004

Ischemic preconditioning (IPC) has been accepted as a heart protection phenomenon against ischemia and reperfusion (I/R) injury. The activation of ATP-sensitive potassium $(K_{ATP})$ channels and the release of myocardial nitric oxide (NO) induced by IPC were demonstrated as the triggers or mediators of IPC. A common action mechanism of NO is a direct or indirect increase in tissue cGMP content. Furthermore, cGMP has also been shown to contribute cardiac protective effect to reduce heart I/R-induced infarction. The present investigation tested the hypothesis that $K_{ATP}$ channels attenuate DNA strand breaks and oxidative damage in an in vitro model of I/R utilizing rat ventricular myocytes. We estimated DNA strand breaks and oxidative damage by mean of single cell gel electrophoresis with endonuclease III cutting sites (comet assay). In the I/R model, the level of DNA damage increased massively. Preconditioning with a single 5-min anoxia, diazoxide $(100\;{\mu}M)$, SNAP $(300\;{\mu}M)$ and 8-(4-Chlorophenylthio)-guanosine-3',5'-cyclic monophosphate (8-pCPT-cGMP) $(100\;{\mu}M)$ followed by 15 min reoxygenation reduced DNA damage level against subsequent 30 min anoxia and 60 min reoxygenation. These protective effects were blocked by the concomitant presence of glibenclamide $(50\;{\mu}M)$, 5-hydroxydecanoate (5-HD) $(100\;{\mu}M)$ and 8-(4-Chlorophenylthio)-guanosine-3',5'-cyclic monophosphate, Rp-isomer (Rp-8-pCPT-cGMP) $(100\;{\mu}M)$. These results suggest that NO-cGMP-protein kinase G (PKG) pathway contributes to cardioprotective effect of $K_{ATP}$ channels in rat ventricular myocytes.

• Molecules and Cells
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• 제40권2호
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• pp.143-150
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• 2017

Homologous recombination (HR) is necessary for maintenance of genomic integrity and prevention of various mutations in tumor suppressor genes and proto-oncogenes. Rad51 and Rad54 are key HR factors that cope with replication stress and DNA breaks in eukaryotes. Rad51 binds to single-stranded DNA (ssDNA) to form the presynaptic filament that promotes a homology search and DNA strand exchange, and Rad54 stimulates the strand-pairing function of Rad51. Here, we studied the molecular dynamics of Rad51 and Rad54 during the cell cycle of HeLa cells. These cells constitutively express Rad51 and Rad54 throughout the entire cell cycle, and the formation of foci immediately increased in response to various types of DNA damage and replication stress, except for caffeine, which suppressed the Rad51-dependent HR pathway. Depletion of Rad51 caused severe defects in response to postreplicative stress. Accordingly, HeLa cells were arrested at the G2-M transition although a small amount of Rad51 was steadily maintained in HeLa cells. Our results suggest that cell cycle progression and proliferation of HeLa cells can be tightly controlled by the abundance of HR proteins, which are essential for the rapid response to postreplicative stress and DNA damage stress.