• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.6
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• pp.1025-1029
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• 2000

This study was conducted to investigate whether a DNA comet assay could be applied for identifying irradiated pork and beef. Pork and beef were irradiated with Co-60 gamma rays at 0.1, 0.3, 0.5, 0.7 and 1.0 kGy, and stored in a freezer Cells separated from the samples were embedded in agarose gel on a slide, dissolved in a lysis solution, and electrophoresed at 2 V/cm for 2.0 min by horizontal electrophoesis. The cells were then stained with a silver staining in order to visualize the DNA using a micro-scope. The DNA fragments of the irradiated cells stretched or migrated out of the cells and formed tails towards the anode, giving the appearance of comets, while unirradiated cells formed very short or no tails. The distance of DNA migration increased with irradiation dose. Since the statistical analysis showed a significant correlation between tail length and irradiation dose, a DNA comet assay could provide not only identification but also estimation of the irradiation dose for irradiated beef and pork.

• Journal of the Korean Society of Food Culture
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• v.19 no.3
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• pp.251-258
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• 2004

The changes in DNA damage were investigated during storage after irradiation. Potato, garlic were irradiated at 0.05, 0.07, 0.1 and 0.15 kGy and stored for 3 months. Ginger was irradiated at 0.01, 0.02, 0.03, 0.04 and 0.05 kGy and stored for 1 month. The comet assay was applied to the sample immediately after irradiation and at the end of storage. Samples were isolated, grounded and the suspended cells were embedded in an agarose layer. After lysis of the cells, they were electrophoresed for 1 min. and then stained. DNA fragmentation in seeds caused by irradiation was quantified as tail length and tail moment (tail length ${\times}%$ DNA in tail) by comet image analyzing system. Right after irradiation, the differences in tail length between unirradiated and irradiated samples were significant(p<0.05) in potato, garlic and ginger. With increasing the irradiation doses, statistically significant longer extension of the DNA from the nucleus toward anode was observed. The results represented as tail moment showed similar tendency to those of tail length. Similarly in the stored samples, even 1 or 3 months after irradiation, all the irradiated samples significantly showed longer tail length than the unirradiated controls. These results indicate that the comet assay could be one of the simple methods of detecting irradiated samples. Moreover, the method could detect DNA damage even after 1 or 3 months after irradiation.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1997.12a
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• pp.101-101
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• 1997

Comet assay, single cell gel electrophoresis has been known as useful, rapid, simple, visual, and sensitive technique for measuring the DNA breakage in mammalian ce1ls. For evaluation of DNA damage using comet assay, early studies reported a change in comet length and intensity with DNA damage using simple visual technique, such as fluorescence microscopy with eyespiece. In recent, some workers are observing and analyzing nucleotide of comets using quantitative fluorescence image analysis system to estimate 'tail moment', which is defined as the product of the tail length and the fraction of total DNA in tail. Our laboratory also adopted the image analysis software for qualification. In addition, many of the practical features of comet assay render it potentially attractive as useful tool for molecular toxicology and carcinogenesis, because the system is already showing considerable promise as rapid predictor in both in vitro and in vivo experimental designs. Recently, the comet assay becomes a attractive technique to study of apoptosis, because apoptotic fragmentation of nuclear DNA into nucleosomal sizes can be evaluated by the comet assay. So, we attempted to apply the comet assay to studying the effect of various stress on the apoptosis-sensitive cell lines. Particularly, focusing on the hyperthermic apoptosis, we could find that heat shock(44˚C for 60 minutes) was sufficient to induced apoptosis in these cell lines. But using the highly sensitive comet assay, we could not detect DNA breaks immediately after heat shock.

• Korean Journal of Food Science and Technology
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• v.36 no.6
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• pp.851-856
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• 2004

Minerals separated from irradiated dried red pepper (whole) at 2.5 kGy or higher showed typical thermoluminescence (TL) glow curves ($TL_1$) at around $150^{\circ}C$, which increased with irradiation dose. The TL ratio ($TL_1/TL_2$) through re-irradiation step at 1 kGy enhanced reliability of TL identification results. DNA comet assay indicated that the intact cell was observed in non-irradiated pepper (seed), while some long tails were found in irradiated ones, showing relationship between irradiation dose and tail length. Log DEPT/APC values increased in proportion to irradiation doses in powdered and whole peppers. Based on overall results, irradiated dried red peppers could be screened using DNA comet assay or log DEFT/APC, and moreover the identification results were verified by TL analysis.

• Molecular & Cellular Toxicology
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• v.5 no.2
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• pp.126-132
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• 2009

The usage and types of chemicals are advancing, specializing, large-scaled increasing, and new chemical exposed workers are concerning to occupational disease. The generation of reactive oxygen in the body from carcinogen, mutation and DNA damage in cancer is protected by natural antioxidants (phytochemicals) with antimutagenic effect. There were many reports of ginsenoside Rb$_1$, Rg$_1$ grievances of the genetic mutation to suppress the effect confirm the genetic toxicity test with chromosomal aberration test and the Comet (SCGE) assay confirmed the suppression effect occurring chromosomal DNA damage. We had wanted to evaluate the compatibility and sensitivity between the chromosomal aberration (CA) test and the Comet assay. We used the CA test and Comet assay to evaluate the anti-genotoxicity of ginsenoside Rb$_1$ and Rg$_1$, in CHO-K1 (Chinese hamster ovary fibroblast) cell in vitro, composed negative control (solvent), positive control (benzo[a]pyrene), test group (carcinogen+variety concentration of ginsenoside) group. The positive control was benzo[a]pyrene (50 $\mu$M), well-known carcinogen, and the negative control was the 1 % DMSO solvent. The test group was a variety concentration of ginsenoside Rb$_1$, Rg$_1$ with 10$^{-8}$%, 10$^{-6}$%, 10$^{-4}$%, 10$^{-2}$%, 1%, 10%. In chromo-somal aberration test, we measured the number of cells with abnormally structured chromosome. In Comet assay, the Olive tail moment (OTM) and Tail length (TL) values were measured. The ratio of cell proliferation was increased 8.3% in 10$^{-8}$%, 10$^{-6}$%, 10$^{-4}$%, 10$^{-2}$%, 1%, 10% Rb$_1$ treated groups, and increased 10.4% in 10$^{-10}$%, 10$^{-8}$%, 10$^{-6}$%, 10$^{-4}$%, 10$^{-2}$%, 1% Rg$_1$ treated groups. In the CA test, the number of chromosomal aberration was decreased all the Rb$_1$ and Rg$_1$ treated groups. In the Comet assay, the OTM values were decreased in all the Rb$_1$ and Rg$_1$ treated groups. To evaluate the compatibility between CA and Comet assay, we compared the reducing ratio of chromosomal abnormalities with its OTM values, it was identified the antimutagenicity of ginsenoside, but it was more sensitive the CA test than the Comet assay. Ginsenoside Rb$_1$ and Rg$_1$ significantly decrease the number of cells with chromosomal aberration, and decrease the extent of DNA migration. Therefore, ginsenoside Rb$_1$, Rg$_1$ are thought as an antioxidant phytochemicals to protect mutagenicity. The in vitro Comet assay seems to be less sensitive than the in vitro chromosomal aberration test.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.323-326
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• 2002

Ionizing radiation can be used to sanitize herbs contaminated by various microorganisms. However, health concerns related to irradiation damage to complex molecules in plants necessitate that methods be developed to monitor such damage. To elucidate DNA damage of herbs caused by irradiation, the DNA comet assay was used for Astragalus membranaceus Bunge and Havenia dulcis Thumb, irradiated at 1, 5, 7, and 10 kGy. With increasing irradiation doses, the tails of comets became longer with average tail length increasing from 17 (non-irradiated) to 124 (10 kGy) $\mu$m in Astragalus membranaceus Bunge. Above 7 kGy, some of the tails were separated from the heads of comets. Distribution patterns of the tail length of In comets selected randomly in the irradiated herbs were analyzed to quantify the DNA damage. These results clearly suggest that the DNA comet assay is an effective and inexpensive tool for the detection of irradiation damage to DNA in herbs.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.52.2-52.2
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• 2010

107P/(4015) Wilson-Harrington is one of possible candidates of the dormant or inactive comet nuclei. It was discovered on a photographic plate exposed with the 48-inch Schmidt at Palomar Observatory on 1949 November 19 UT, displaying the faint extended cometary tail. No comet activity has not been after 1949 apparition. Here we present the optical observations of 107P/(4015) Wilson - Harrington during 2009/2010 apparition taken in search of low-level comet activity. Our photometric and spectroscopic data were collected 28 - 86 days after the perihelion passage on 2009 October 22 in a wide range of solar phase angle of 39-68 degree. A disk-integrated phase function was constructed, giving a geometric albedo of 0.055+/-0.012, phase integral of q=0.34, and Bond albedo of A_B=0.019. The photometric property shows profile similar to low albedo asteroids and comet nuclei. Any emission lines were found in our spectrum, giving a flat reflectance similar to low albedo asteroids. Although we could not find any evidence for the comet activity in our photometric and spectroscopic data, we found an upper limit of the fractional active area of 0.001%. We derived the upper limit of the optical depth of the dust trail and tail 7x10^{-10}. We conclude that 107P/(4015)Wilson-Harrington became completely dormant or inactive in 2009/2010 return.

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.466-471
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• 2008

Little is known about DNA-level and physiological levels for health assessments of stream or river environments. Recently, comet assay, so called Single Cell Gel Electrophoresis (SCGE) is introduced for assessments of DNA damage in the medical science, food science and mammal toxicology. The comet assay is known as a biomarker which is one of the best barometers in assessing the DNA damage by oxidative stress. In this study, we conducted the comet assay using sentinel species, Zacco platypus, as one of the pre-warning alarm systems for the aquatic ecosystem health assessments and also applied it to Gap Stream as a model system. Tail extent moments in the S1 and S2 were 5.20 and 9.90 respectively and the moment was 19.89 in the S3. Statistical ANOVA in the tail moments showed a significant difference (n=75, p<0.05) between S1 and S3. Also, the proportions of DNA in the tail were 14.47, 23.64, and $30.04{\mu}m$ in the upstream (control site), midstream, downstream sites, respectively. Our results in the downstream were accord with previous studies of individual-level, population-level, and community-level in Gap Stream. Our results suggest that the comet assay may be used as an important tool for diagnosing ecological health of aquatic ecosystems in the level of DNA.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.18-23
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• 2002

The detection characteristics of gamma-irradiated $(0{\sim}4\;kGy)$ soybeans produced in Korea and China were investigated by thermoluminescene (TL), electron spin resonance (ESR), and DNA comet assay. The TL glow curves were shown at around $200^{\circ}C$ for irradiated soybeans, while that at $280^{\circ}C$ for the non-irradiated one. The normalization with a re-irradiation step at 1 kGy could verify the above detection results. The Korean soybean showed higher glow curves than Chinese did. The ESR spectroscopy for husks of irradiated soybeans revealed specific signals (g = 2.02374, 1.98715) derived from cellulose radical, which intensities were proportional to irradiation does, with the higher peaks in Chinese sample than Korean one. The DNA comet for the non-irradiated sample showed no or little tails, while those for irradiated samples above 0.5 kGy were remarkably changed in their length, size, and concentration, thus resulting in distinguishing non-irradiated from irradiated samples. As a result, TL, ESR, and DNA comet determinations were found suitable for the detection of irradiated soybean at 0.5 kGy or more, and negligible differences were observed between Korean and Chinese origins in their detection characteristics.

• Journal of Nutrition and Health
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• v.35 no.2
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• pp.213-222
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• 2002

The alkaline comet assay has been used with increasing popularity to investigate the level of DNA damage in biomonitoring studies within the last decade in Western countries. The purpose of this study was to evaluate the usefulness of the alkaline comet assay as a biomarker of oxidative DNA damage for monitoring in the Korean population, and also to evaluate the effect of nutritional status and lifestyle factors on H2O2 induced oxidative DNA damage measured by the alkaline comet assay in human lymphocytes. The study population consisted of 61 healthy Korean male volunteers, aged 20-28. Epidemiological background data including dietary habits, smoking habits and anthropometrical measurements were collected through personal interviews. After blood collection, the comet assay in peripheral lymphocytes and plasma lipids analysis was carried out and the results analyzed. Tail moment (TM) and tail length (TL) of the comet assay were use\ulcorner to measure DNA damage in the lymphocytes of the subjects. Statistically significant (p < 0.05) positive correlations were observed between DNA damage (TM or TL) and smoking habits expressed as cigarettes smoked per day and pack years (r = 0.311 and 0.382 for TM, r = 0.294 and 0.350 for TL, respectively). There were also significant positive correlations between DNA damage parameter and waist-hip ratio. Higher plasma triglyceride levels were associated with increased damage to DNA. There were no correlations between the consumption frequencies of vegetables and DNA damage to the subjects. However, consumption frequencies of fruit and fruit juice intake were inversely associated with the TM and TL. The results indicate that die comet assay is a simple, rapid and sensitive method for detecting lymphocyte DNA damage induced by cigarette smoking. Consumption of fruit or fruit juices could potentiall modify the damaged DNA in the human peripheral lymphocytes of young Korean men.