• 한국자기공명학회논문지
• /
• 제10권2호
• /
• pp.175-187
• /
• 2006

Binding interactions between a positively charged porphyrin derivative TMAP(meso-tetra(p-trimethylanilinium-4-yl)porphyrin) and triple helical $(dT)_{12}{\cdot}(dA)_{12}{\cdot}(dT)_{12}$, as well as double helical $(dA)_{12}{\cdot}(dT)_{12}$ have been studied with NMR, UV and CD spectroscopy to obtain the detailed information about the binding mode and binding site. UV melting studies showed both DNA duplex and triple helix represented very similar UV absorption patterns upon binding TMAP, but the presence of third strand of triple helical $(dT)_{12}{\cdot}(dA)_{12}{\cdot}(dT)_{12}$, inhibited improvement in thermal stability in terms of melting temperature, $T_m$. In addition, the TMAP molecule is thought to bind to the major groove, according to CD and NMR data. But absence of the clear isosbestic point in UV absorption spectra represented that binding of TMAP to DNA duplex as well as DNA triplex did not show a single binding mode, rather complex binding modes.

• 한국동물학회지
• /
• 제26권1호
• /
• pp.19-28
• /
• 1983

본 연구는 알킬화제이며 항암항생제인 Mitomycin C(MMC)와 Bleomycin(BLM)이 DNA 복제 및 회복에 미치는 영향을 규명하고, 아울러 MMC에 의한 "유발상해회복"이 포유동물세포에 유발되는지 밝히고자 수행하였다. 이를 위해 자기방사법에 의한 비주기 DNA 합성율과 알카리 유출법에 의한 DNA단사절단율을 측정하였다. CHO세포에 MMC를 제 1차 $(MMC_1)$ 처리한 후 5시간 뒤에 제 2차 $(MMC_2)$로 처리하여 얻은 결과는 다음과 같았다. 1. BLM은 비주기 DNA합성을 매우 적게 유발시켰으며, BLM $5\\mug/ml$의 농도에서 부터 비주기 DNA합성율은 증가를 보이지 않았다. BLM은 처리후 1.5시간까지 DNA합성억제를 보였으며, 1.5시간후 DNA합성율이 증가되었으나, 대조군의 60% 수준까지 회복되었을 뿐이다. 2. MMC에 의해 유발된 비주기 DNA합성은 농도에 따라 비례하였으며, 배양후 시간의 간격에 따라 비례하여 감소하였다. 제 1,2차 MMC를 처리한 세포의 비주기 DNA합성은 제 1차만 처리한 세포의 비주기 DNA합성보다 많았다. 3. 알카리 유출법 결과는 MMC에 의하여 유발된 DNA 단백질 연결로 인한 DNA 단사절단율이 농도에 비례함을 나타내었다. DNA 단백질 연결로 인한 DNA 단사절단율은 배양후의 시간에 비례해서 감소되었다. 이러한 결과는 MMC와 BLM 모두가 DNA 상해제임과 MMC에 의한 DNA 상해 부위의 복제율이 어떠한 유발기작에 의하여 촉진됨을 시사한다.촉진됨을 시사한다.

• BMB Reports
• /
• 제39권2호
• /
• pp.140-144
• /
• 2006

A deoxyriboendonuclease has been purified to near homogeneity from a fast growing mycobacterium species, M. smegmatis and characterized to some extent. The size of enzyme is about 43 kDa as determined by a denaturing gel analysis. It shows optimum activity at $32^{\circ}C$ in Tris-HCl buffer (pH 7.2) containing 2.5 mM of $MgCl_2$. Both EDTA and $K^+$ but not $Na^+$ inhibit its activity. Evidences show that the enzyme is not a restriction endonuclease but catalyzes the endonucleolytic cleavage of both the double- as well as the single-strand DNA non-specifically. It has been shown that the cleavage by this enzyme generates DNA fragments carrying phosphate groups at 5' ends and hydroxyl group at the 3' ends, respectively. Analysis reveals that no endonuclease having size and property identical to our deoxyriboendonuclease had been purified from M. smegmatis before. The property of our enzymes closely matches with the deoxyriboendonucleases purified from diverse sources including bacteria.

• Journal of Microbiology and Biotechnology
• /
• 제25권4호
• /
• pp.492-495
• /
• 2015

This study provides evidence that RecG regulates the expression of the OxyR-independent gene mexA in Pseudomonas aeruginosa PAO1. A reduction in mexA expression was observed in the absence of RecG, but not OxyR, by northern blot and quantitative real-time PCR analyses. The canonical palindromic RecG binding sequence was present upstream of the mexA promoter, and bound purified RecG and single strand-binding protein. These data reveal a novel mechanism of OxyR-independent gene transcription by RecG.

• Animal cells and systems
• /
• 제5권2호
• /
• pp.153-156
• /
• 2001

A key aspect of genomic research in the “post-genome era”is to associate sequence variations with heritable phenotypes. The most common variations in the human genome are single nucleotide polymorphisms (SNPs) that occur approximately once in every 500 to 1,000 bases. Although analyzing the phenotypic outcome of these SNPs is crucial to facilitate large-scale association studies of genetic diseases, detection of SNPs from an extended number of human DNA samples is often difficult, labor-intensive and time-consuming. Recent development in SNP detection methods using DNA microarrays and mass spectrophotometry has allowed automated high throughput analyses, but such equipments are not accessible to many scientists. In this study, we demonstrate that a simple PCR-based method using primers with a mismatched base at the 3'-end provides a fast and easy tool to identify known SNPs from human genomic DNA in a regular molecular biology laboratory. Results from this PCR amplification of specific alleles (PASA) analysis efficiently and accurately typed the Q576R polymorphism of human IL4 receptor from the genomic DNAs of 29 Koreans, including 9 samples whose genotype could not be discerned by the conventiona1 PCR-SSCP (single strand conformation polymorphism) method. Given the increasing attention to disease-associated polymorphisms in genomic research, this alternative technique will be very useful to identify SNPs in large-scale population studies.

• 약학회지
• /
• 제51권6호
• /
• pp.415-423
• /
• 2007

This study was to evaluate the genotoxic effects of airborne particulate matters using single cell gell elec trophoresis (comet assay) in A549 human lung carcinoma cells. The total suspended particulate (TSP) was collected on back-up filter in Chuncheon, Kangwon Do, South Korea from April, 2003 to February, 2005. The concentrations of TSP, B(a)p and most of heavy metals seemed to be higher in spring and winter, and lower in summer. And they showed higher concentration in the commercial areas and the residential area having more traffics than in the rural area. It was found that A549 cells interacting with the organic extract of TSP showed more DNA single-strand breaks compare to untreated cells. The genotoxicity of the organic extract of TSP was increased with the pre-treatment of S-9 mixture during the culture or with the treatment of endonuclease after cell lysis. The DNA damage by the organic extract of TSP was higher in winter and the commercial area than in summer and the rural area. This study suggests that TSP, heavy metals and B(a)P analyzed showed significant variation depend on the seasons and the areas which are correlated with the DNA damage evaluated by Comet assay, indicating that genotoxic biomarker is useful for toxicological evaluation of air quality.

• Journal of Preventive Medicine and Public Health
• /
• 제37권4호
• /
• pp.373-380
• /
• 2004

Objectives : There has been gradually increasing concern about the adverse health effects of electromagnetic radiation originating from cell phones which are widely used in modern life. Cell phone radiation may affect human health by increasing free radicals of human blood cells. This study has been designed to identify DNA damage of blood cells by electromagnetic radiation caused by cell phone use. Methods : This study investigated the health effect of acute exposure to commercially available cell phones on certain parameters such as an indicator of DNA damage for 14 healthy adult volunteers. Each volunteer during the experiment talked over the cell phone with the keypad facing the right side of the face for 4 hours. The single cell gel electrophoresis assay (Comet assay), which is very sensitive in detecting the presence of DNA strand-breaks and alkali-labile damage in individual cells, was used to assess peripheral blood cells (T-cells, B-cells, granulocytes) from volunteers before and after exposure to cell phone radiation. The parameters of Comet assay measured were Olive Tail Moment and Tail DNA %. Results : The Olive Tail Moment of B-cells and granulocytes and Tail DNA % of B-cells and granulocytes were increased by a statistically significant extent after 4-hour use of a cell phone compared with controls. Conclusion : It is concluded that cell phone radiation caused the DNA damage during the 4 hours of experimental condition. Nonetheless, this study suggested that cell phone use may increase DNA damage by electromagnetic radiation and other contributing factors.

• 환경생물
• /
• 제19권1호
• /
• pp.19-24
• /
• 2001

병해충을 막기 위해 농업용 살충제가 광범위하게 사용되고 있다. 농약사용에 따른 생물학적 위해가 우려되며 농약이 또 다른 환경유해요인과 인체에 상승적으로 작용할 경우 농업재해로 이어질 가능성이 있다. 다양한 인자에 의한 DNA손상을 감지하는데 유용한 단세포 겔 전기영동법을 이용하여 살충제와 방사선에 의한 사람 림프구 DNA손상을 평가하였다. 각기 다른 농도로 살충제를 10분간 전처리한 림프구와 정상 림프구에 0-2.0 Gy의 방사선으로 조사한 다음 DNA 손상도를 평가하였다. DNA가닥 절단에 대한 표식인 tail moment의 증가는 감마선에 대해서 뚜렷한 선량-반응 관계를 나타내었다. 단세포 겔 전기영동법을 통한 평가결과 권장 사용농도 이상의 살충제는 림프구에 대한 유전독성을 나타내었을 뿐 아니라 방사선과 함께 상승작용을 일으켜 림프구 DNA손상을 더욱 증가시키는 것이 확인되었다. 이와 같은 결과는 환경재해의 방재 및 예방 조치에 필요한 생물정보를 사전에 제공하는 의미를 가진다.

• Journal of Microbiology and Biotechnology
• /
• 제14권2호
• /
• pp.268-275
• /
• 2004

To investigate the potential application of the single-cell gel electrophoresis (SCGE) assay to carp as an aquatic pollution monitoring technique, gill, liver, and blood cells were isolated from carp exposed to a direct-acting mutagen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), or indirect mutagen, $benzo[\alpha]pyrene$ $(B[\alpha]P)$, then the DNA strand breakage was analyzed using the assay. Based on testing 5 different cell isolation methods and 6 electrophoretic conditions, the optimized assay conditions were found to be cell isolation by filter pressing and electrophoresis at a lower voltage and longer running time (at 0.4 V/cm for 40 min). In preliminary experiments, gill and liver cells isolated from carp exposed to MNNG in vitro exhibited DNA damage signals even with 0.5 ppb exposure, which is a much higher dose than previously reported. In the gill cells isolated from carp exposed to 0.01-0.5 ppm MNNG in vivo, significant dose-and time-dependent increases were observed in the tail for 4 days. As such, the linear correlation between the relative damage index (RDI) values and time for each dose based on the initial 48-h exposure appeared to provide effective criteria for the genotoxicity monitoring of direct-acting mutagenic pollution. In contrast, the in vivo exposure of carp to 0.25-1.0 ppm of $B[\alpha]P$ for 7 days resulted in dose-and time-dependent responses in the liver cells, in which 24-h delayed responses for metabolizing activation and gradual repair after 48 h were also observed. Thus, the negative-sloped linear correlation between the RDI and time at each dose based on the initial 48 h appeared to provide more effective criteria for the genotoxicity monitoring of indirect mutagenic pollution.

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권4호
• /
• pp.2393-2399
• /
• 2013

Objective: Mitochondrial DNA (mtDNA) is considered a hotspot of mutations in various tumors. However, the relationship between microsatellite instability (MSI) and mtDNA copy number alterations in lung cancer has yet to be fully clarifieds. In the current study, we investigated the copy number and MSI of mitochondrial genome in lung carcinomas, as well as their significance for cancer development. Methods: The copy number and MSI of mtDNA in 37 matched lung carcinoma/adjacent histological normal lung tissue samples were examined by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) assays for sequence variation, followed by sequence analysis and fluorogenic 5'-nuclease real-time PCR. Student's t test and linear regression analyses were employed to analyze the association between mtDNA copy number alterations and mitochondrial MSI (mtMSI). Results: The mean copy number of mtDNA in lung carcinoma tissue samples was significantly lower than that of the adjacent histologically normal lung tissue samples (p<0.001). mtMSI was detected in 32.4% (12/37) of lung carcinoma samples. The average copy number of mtDNA in lung carcinoma samples containing mtMSI was significantly lower than that in the other lung carcinoma samples (P<0.05). Conclusions: Results suggest that mtMSI may be an early and important event in the progression of lung carcinogenesis, particularly in association with variation in mtDNA copy number.