• Journal of the Korean Chemical Society
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• v.29 no.3
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• pp.271-276
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• 1985

An anomalous absorbance-temperature profile of calf thymus DNA, having a trough preceding the initiation of the melting, occurs at the spermine concentration, where the DNA collapses into a compact structure. The cooperativity, enthalpy, and the midpoint of the phase transition to the trough region are more sensitive to ethidium bromide than those of the Tm region. As the concentration of ethidium bromide added is increased, the peak size of the trough is decreased, while the Tm remains essentially constant.

• Toxicological Research
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• v.17 no.4
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• pp.249-253
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• 2001

Fumonisin B1, a mycotoxin, is thought to induce esophageal cancer in humans and apoptosis in animal cells by inhibiting ceramide synthase. Dumonisin Bl may also generate reactive oxygen species directly or indirectly, leading to DNA damage and lipid peroxidation. In this study, a DNA fragmentation assay, dichlorofluorescein (DCF) analysis, and single cell gel electrophoresis (SCGE) were used to investigate the involvement of cellular free radicals, specifically hydrogen peroxide, in the DNA damaging activity of fumonisin B1. From an in vitro DNA fragmentation assay, E. coli DNA, damage by fumonisin Bl was increased by the addition of superxide dismutase (SOD) and decreased by catalase. SCGE and DCF analysis in vivo showed that the nuclear DNA damage and intracellular free radicals in cultured rat hepatocytes treated with fumonisin B1 were increased with the concentration of fumonisin Bl . DNA damage and free radical generation were inhibited by the addition of catalase. Fumonisin Bl , in the presence of SOD, produces hydrogen peroxide causing oxidative DNA damage and protein malfunction, leading to genotoxicity and cytotoxicity of the toxin.

• YAKHAK HOEJI
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• v.36 no.5
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• pp.449-454
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• 1992

The effect of radioprotective ginseng protein fraction on DNA repair capacity was determined by measuring the amount of $^{3}H-thymidine$ incorporated into DNA in the process of repair synthesis for UV damaged DNA. CHO-Kl cells were prepared whose semiconservative replication was inhibited by trimethylpsoralen plus near-UV(PUVA) treatment. When the cells were exposed to UV light alone, the DNA repair capacity was increased at first and then decreased as UV dose increased. However, when the ginseng fraction was treated to the cells, the DNA repair capacity was kept increasing regardless of UV dose increment. When the concentration of protein contained in the added fraction was increased gradually, the repair capacity was also increased almost linearly showing dose-response relationship of the effect. These results suggest that the enhancement of DNA repair capacity of the cell can be one of the mechanisms of radioprotection by the ginseng fraction.

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.163-168
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• 1983

The penicillin resistant plasmid DNA was prepared from Streptomyces bobili YS-40, producing penicillinase, by the phenol extraction method and introduced into Bocillus subtilis IAM 12118 by the transformation procedure of Mahler method. The optimal pH and temperature on the transformation was 7.0, 3$0^{\circ}C$ respectively. Above 20 minutes contact of plasmid DNA and recipient cell was shown the high transformation frequency. The transformant of penicillin resistance was proportionally increased as increase of the DNA concentration. The addition of lysine in transformation system increased the transformation frequency about 6-fold and the addition of the chloramphenicol did not affect the transformation frequency.

• Korean Journal of Food Science and Technology
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• v.48 no.2
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• pp.128-132
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• 2016

In this study, polyethylene glycol (PEG) was used to improve DNA amplification efficiency during whole genome amplification (WGA). Amplification efficiency was determined by adding PEG with different molecular weights to the WGA reaction. The greatest increase in amplification efficiency was obtained with PEG 4,000 used at 1.5% concentration. Foodborne pathogenic DNA was amplified by WGA and quantitatively analyzed by real-time polymerase chain reaction. DNA of Salmonella serotype Typhimurium, Listeria monocytogenes, and Vibrio parahaemolyticus was amplified 7,777.01, 9,981.22, and 1,239.03 fold, respectively, by WGA. On adding PEG in the WGA reaction (i.e., enhanced WGA [eWGA]), 18-40-fold more DNA amplification was achieved. Thus, these analyses showed that foodborne pathogens, which are usually present at very low concentration in foods, can be detected by real-time PCR and WGA.

• Toxicological Research
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• v.29 no.4
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• pp.293-298
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• 2013

A method of detecting lead was developed using square wave anodic stripping voltammetry (SWASV) with DNA-carbon nanotube paste electrode (CNTPE). The results indicated a sensitive oxidation peak current of lead on the DNA-CNTPE. The curves were obtained within a concentration range of 50 $ngL^{-1}-20mgL^{-1}$ with preconcentration time of 100, 200, and 400 sec at the concentration of $mgL^{-1}$, ${\mu}gL^{-1}$, and $ngL^{-1}$, respectively. The observed relative standard deviation was 0.101% (n = 12) in the lead concentration of 30.0 ${\mu}gL^{-1}$ under optimum conditions. The low detection limit (S/N) was pegged at 8 $ngL^{-1}$ ($2.6{\times}10^{-8}M$). Results showed that the developed method can be used in real-time assay in vivo without requiring any pretreatment and pharmaceutical samples, and food samples, as well as other materials requiring water source contamination analyses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.300-307
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• 1987

The present study was investigated on the DNA damage by the peroxidation of polar and non-polar lipid fractionated from mackerel lipid to elucidate the DNA damage mechanism by fish oil peroxidation. The degree of DNA damage by polar lipid peroxidation became greater with the increase of its concentration, and such DNA damage was induced below 100 millieq./kg in POV for 4 days incubation. Among the polar lipid peroxidation products, singlet oxygen $^1O_2$ and superoxide anion ${\cdot}O_2^-$ greatly affected to the DNA damage than hydrogen peroxide $H_2O_2$ and hydroxyl radical ${\cdot}OH$. Non-polar lipid peroxidation also induced the DNA damage with the increase of its concentration, but such effect was lower than the case of total lipid and polar lipid. And, the effects of active crygens on the DNA damage by non-polar lipid peroxidation was the same as in the case of total and polar lipid peroxidation.

• BMB Reports
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• v.31 no.4
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• pp.384-390
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• 1998

DNA fragments (51-587 bp) were separated by capillary electrophoresis using entangled polymer, hydroxyethylcellulose, in uncoated fused silica capillary columns. The factors affecting the separation of DNA fragments with hydroxyethylcellulose media were evaluated, i.e., the concentration of buffer and entangled polymer, effects of additives (methanol, ethidium bromide, EDTA), temperature, and injection methods. Maximum performance was obtained by adding 5% methanol in 0.5% hydroxyethylcellulose solution at $30^{\circ}C$. Addition of methanol in polymer media increased the resolution of small size DNA fragments (< 100 bp). On the other hand, addition of ethidium bromide and EDTA, which are commonly used in conventional DNA separation, reduced the resolution of DNA fragments in the polymer solution. It turns out that the separation behavior of DNA in entangled polymer is more sensitive to the running condition compared to that in polyacrylamide gel-filled capillary, but the reproducibility of DNA separation in entangled polymer is reliable.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.2
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• pp.92-97
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• 2002

One of the important roles of a DNA chip is the capability of detecting genetic diseases and mutations by analyzing DNA sequence. For a successful electrochemical genotyping, several aspects should be considered including the chemical treatment of electrode surface, DNA immobilization on electrode, hybridization, choice of an intercalator to be selectively bound to double standee DNA, and an equipment for detecting and analyzing the output signal. Au was used as the electrode material, 2-mercaptoethanol was used for linking DNA to Au electrode, and methylene blue was used as an indicator that can be bound to a double stranded DNA selectively. From the analysis of reductive current of this indicator that was bound to a double stranded DNA on an electrode, a normal double stranded DNA was able to be distinguished from a single stranded DNA in just a few seconds. Also, it was found that the peak reduction current of indicator is proportional to the concentration of target DNA to be hybridized with probe DNA. Therefore, it is possible to realize a sim71e and cheats DNA sensor using the electrochemical measurement for genotyping.

• Journal of Preventive Medicine and Public Health
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• v.38 no.4
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• pp.437-442
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• 2005

Objectives : DNA methylation is one of the best characterized epigenetic mechanisms that play a regulatory role in genome programming and imprinting during embryogenesis. In this present study, we investigated the association between DNA methylation in the human placenta and the maternal folate and homocysteine concentrations on the Methylenetetrahydrofolatereductase (MTHFR) genetic polymorphism during pregnancy. Methods : We investigated 107 pregnant women who visited Ewha Woman's University Hospital for prenatal care during their $24{\sim}28$ weeks-period of gestation. During the second trimester, we measured the serum homocysteine and folate concentrations . The MTHFR 677 genetic polymorphism was determine by performing PCR-RFLP assay. The expression of DNA methylation in the human placentas was estimated by using immunohistochemistry method. Results : Serum folate was negatively correlated with the serum homocysteine concentration for all the MTHFR genotypes. We found positive correlation between the folate concentrations and the DNA methylation in the human placenta (p<0.05). An increasing concentration of homocysteine was associated with reduced DNA methylation in the human placenta. The coefficient value was -2.03 (-3.77, -0.29) on the regression model (p<0.05). Conclusion : These findings suggest that the maternal folate and homocysteine levels along with the MTHFR 677 genetic polymorphism during pregnancy affect the DNA methylation in the human placenta.