• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.553-560
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• 1991

In the previous paper (10). a new temperate phage, Sigma FA1 had been isolated from B. circulans. Sigma FA1 had an icosahedral head with a diameter of about 70 nm, and a tail about 15 nm long, and beared a circularly permuted, linear duplex DNA. Signla FA1 killed sensitive cells by a single-hit process. Phage DNA injected into the cell immediately after infection was degraded slowly. Our results indicate that the killing action of Sigma FA1 is different from the phenomenon of abortive infection and suggest that the killing might be caused by a proteinaceous component of Sigma FA1.

• Molecules and Cells
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• v.25 no.4
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• pp.545-552
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• 2008

A hepadnaviruses replicates its DNA genome via reverse transcription of an RNA template (pregenomic RNA or pgRNA), which has a cap structure at the 5' end and a poly(A) tail at the 3' end. We have previously shown that the 5' cap is indispensable for encapsidation of the pgRNA. A speculative extension of the above finding is that the cap contributes to encapsidation via its interaction with the poly(A) tail, possibly involving eIF4E-eIF4G-PABP interaction. To test this hypothesis, poly(A)-less pgRNAs were generated via cleavage by a cis-acting hepatitis delta virus ribozyme sequence. We found that accumulation of the poly(A)-less pgRNA was markedly diminished, mostly likely due to its reduced stability. Importantly, however, the remaining poly(A)-less pgRNAs were nonetheless encapsidated and reverse transcribed normally when the reduced stability was taken account. Our finding clearly contradicts the notion that the poly(A) tail has any function in encapsidation and viral reverse transcription.

• Molecular & Cellular Toxicology
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• v.1 no.2
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• pp.111-115
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• 2005

Ultraviolet (UV) radiation to mammalian skin is known to alter cellular function via generation of Reactive Oxygen Species (ROS), DNA damage and DNA lesions, such as pyrimidine dimmers and photoproducts, which could lead to DNA mutation if they are not repaired. In this study, we have investigated the reduction of DNA damage and of apoptosis with a particular attention to genetic effect of paeoniflorin in Normal Human Epidermal Keratinocytes (NHEK). After UVB irradiation from $10\;to\;500mJ/cm^{2}$ to NHEK, Mean Tail Moments (MTM) were increased with UVB dose increase. The greatest amount of strand breaks was induced at $500mJ/cm^{2}$ of UVB. Even at the lowest dose of UVB ($10mJ/cm^{2}$), change in MTM was detected (P<0.0001). Pretreated cell with 0.1% paeoniflorin maximally reduced the level of DNA damage to about 21.3%, compared to untreated cell. In the lower concentrations less than 0.01% of paeoniflorin, MTM had a small increase but paeoniflorin still had reductive effects of DNA damage. We measured the apoptosis suppression of paeoniflorin with annexin V flous staining kit. As we observed under the fluorescence microscopy to detect apoptosis in the irradiated cell, the fluorescence intensity was clearly increased in the untreated cell, but decreased in treated cells with paeoniflorin. These results suggest that paeoniflorin reduces the alteration of cell membranes and prevents DNA damage. Therefore, the use of paeoniflorin as a free radical scavenger to reduce the harmful effects of UV lights such as chronic skin damage, wrinkling and skin cancer can be useful to prevent the formation of photooxidants that result in radical damage.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.614-620
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• 2005

The antioxidative effect of Ecklonia cava, a brown marine alga, was investigated on radical scavenging, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), and hydroxyl and alkyl radicals, using an electron spin resonance (ESR) technique, and on the inhibition of $H_2O_2$-induced DNA damage using comet assay. E. cava was enzymatically hydrolyzed with five food industrial proteases (Alcalase, Flavourzyme, Kojizyme, Neutrase and Protamex) to prepare water-soluble extracts. All the proteolytic hydrolysates exhibited strong dose-dependent radical scavenging activities (above 80%) at a concentration of $2.5\;{\mu}g/mL$. Kojizyme extract (obtained by proteolytic hydrolysation of E. cava with Kojizyme) showed the highest hydroxyl radical scavenging activity of around 98%. In addition, the $H_2O_2$-induced DNA damage was determined using a comet assay, which was quantified by measuring the tail length. Reduction of DNA damage increased with increasing concentrations of Kojizyme extract from E. cava. These results indicated that E. cava has a potential as a valuable natural antioxidative source.

• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.89-94
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• 2001

Recently, single cell gel electrophoresis, also known as comet assay, is widely used for the detection and measurement of DNA strand breaks in vitro and in vivo in many toxicological fields such as radiation exposure, human monitoring and toxicity evaluation. As well defined, comet assay is a sensitive, rapid and visual method for the detection of DNA strand breaks in individual cells. Briefly, a small number of damaged cells suspended in a thin agarose gel on a microscope slide were lysed, unwinded, electrophoresed, and stained with a fluorescent DNA binding dye. The electric current pulled the charged DNA from the nucleus such that relaxed and broken DNA fragments migrated further. The resulting images which were subsequently named for their appearance as comets, were measured to determine the extent of DNA damages. However, some variations could be occurred in procedures, laboratories's conditions and kind of cells used. Hence, to overcome and to harmonize these matters in comet assay, International Workshop on Genotoxicity Test Procedure (IWGTP) was held with several topics including comet assay at Washington D.C. on March, 1999. In spite of some consensus in procedures and conditions in IWGTP, there are some problems still remained to be solved. In this respect, we attempted to set the practical optimal conditions in the experimental procedures such as lysis, unwinding, electrophoresis and neutralization conditions and so on. First of all, we determined optimal lysis and unwinding time by using 150 $\mu$M methyl methanesulfonate (MMS) which is usually used concentration. And then, we determined optimal positive control concentrations of benzo(a)pyrene (BaP) and MMS in the presence and absence of S9 metabolic activation system, respectively.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.350-354
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• 2015

BACKGROUND: Botanical insecticides, especially Azadirachta Indica extract (AIE) and Sophorae radix extract (SRE) are widely used in Agriculture field. In our previous studies on genotoxicity test of AIE and SRE samples, a suspicious clastogenic properties was shown. Herein, we investigated the DNA damage effect of these botanical insecticide samples through the in vitro comet assay. METHODS AND RESULTS: Chinese hamster lung (CHL) fibroblast cell line was used, and methyl methanesulphonate was as positive control. Respective two samples of AIE and SRE were evaluated using Single Cell Gel Electrophoresis (Comet) assay and measured as the Olive tail moment (OTM). Results from this study indicated that all tested AIE and SRE samples did not show DNA damage in comet assay using CHL cells, compared with control. CONCLUSION: AIE and SRE samples used in this study were not cause genetic toxicity and are suitable for use as organic materials.

• Journal of Nutrition and Health
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• v.42 no.5
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• pp.442-452
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• 2009

Smoking has been known to exacerbate the initiation and propagation of oxidative stresses. Efforts have been made to reduce the smoking-induced oxidative stresses using commercial dietary supplements. Propolis is the resinous substance collected by bees from the leaf buds and bark of trees, especially poplar and conifer trees. In this trial, we examined whether a daily supplementation of 800 mg propolis can protect endogenous lymphocytic DNA damage and modulate antioxidative enzyme activities and the level of antioxidant vitamin in smokers using a placebo-controlled, doubleblinded cross-over trial. After two weeks of running-in period, 29 smokers (mean age 34.38 ${\pm}$ 1.73) received 6 tablets/day of either propolis or placebo pills for 4 weeks. After 2 weeks of washout period the subjects switched they pills for cross-over study. The degree of DNA damage (assessed by tail DNA, tail length and tail moment) was not significantly changed with propolis intake or placebo intake. Similarly, total antioxidant status (TAS) remained at the same level regardless of the treatment. Erythrocyte catalase, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), plasma vitamin C and tocopherol level did not differ before and after propolis treatment, and did not differ between treatments. Putting all these results together, we would suggest that it is still too early to claim that propolis possess antioxidative activities.

• Journal of Nutrition and Health
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• v.39 no.1
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• pp.18-27
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• 2006

Smoking is well known to be associated with increased indices of tree radical-mediated damage of DNA, indicating that smoking may exacerbate the initiation and propagation of oxidative stresses, which are potential underlying processes in the pathogenesis of many diseases. The purpose of this study was to evaluate whether a daily regimen of green vegetable drink supplementation to smokers can be protective against endogenous lymphocytic DNA damage and whether it could enhance other antioxidant status. Twenty nonsmokers and nineteen smokers aged 23-60 were given 240 ml of green vegetable drink every day for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The 8 weeks of green vegetable drink consumption resulted in a significant decrease (p = 0.000, by paired t-test) in lymphocyte DNA damage expressed by TL (before: $63.13{\pm}1.05$ vs after: $37.86{\pm}10.83$, before: $66.73{\pm}1.24$ vs after: $36.51{\pm}1.13$), TM (before: $14.55{\pm}0.61$ vs after: $6.61{\pm}0.25$, before: $15.36{\pm}0.45$ vs after: $6.65{\pm}0.38$) and $\%$ DNA in tail (before: $19.7{\pm}0.41$ vs after: $16.6{\pm}0.37$, before: $20.6{\pm}0.31$ vs after: $17.1{\pm}0.5$) in both nonsmokers and smokers respectively. Vitamin C and TRAP level was not significantly changed after the supplementation. In conclusion, these results support the hypothesis that green vegetable drink exert a cancer-protective effect partially via a decrease in oxidative damage to DNA.

• Journal of Nutrition and Health
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• v.36 no.3
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• pp.255-261
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• 2003

Food irradiation has been steadily increasing in many countries in line with increasing international trade and concerns about naturally occurring harmful contaminants in food. Although irradiation provides an excellent safeguard for the consumer by destroying almost 100% of harmful bacteria, it is necessary to ensure the safety of irradiated foods. This study was performed to investigate the effect of an irradiated diet on lipid peroxidation in the plasma, liver, small intestinal mucosa, and lymphocyte DNA damage in mice. Eight-week old ICR mice were assigned to two groups to receive either non-irradiated or irradiated (10 kGy) diets containing 20.38% fish powder and 6.06% sesame seeds for 4 weeks. The resulting changes in the degrees of lipid peroxidation were evaluated based on the level of plasma and liver thiobarbituric acid reactive substance (TBARS), transmission electron micrograph of jejunal mucosa, and free radical-induced oxidative DNA damage in lymphocytes, as measured by alkaline comet assay (single cell gel electrophoresis). The peroxide values of the gamma irradiated diet were measured every week, and the sample for comet assay was taken at the end of the four week experimental period. There was no significant difference in food efficiency ratio between the two groups. The peroxide values of the diet were immediately increased to 35.5% after gamma irradiation and kept on increasing during storage. After 4 weeks, no differences in tissue or plasma TBARS value were observed between the two groups, but epithelial cells of jejumum showed osmiophillic laminated membranous structures, considered as myelin figures,. The oxidative DNA damage expressed as tail moment (TM) increased 30% in the blood lymphocytes of the mice fed the irradiated diet. In conclusion, the comet assay sensitively detected differences in lymphocyte DNA damage after feeding with the irradiated diet for 4 weeks. However, in order to ensure the safety of irradiated foods, it would be more useful to conduct a long-term feeding regimen using an irradiated diet and examine the level of lipid peroxidation and the state of oxidative stress in a greater range of organs.

• Animal Systematics, Evolution and Diversity
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• v.8 no.2
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• pp.231-242
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• 1992

Samples of two species of genus Ratts(black rat, Rattus rasttus Linnaeus; common rat, Rattus norvegicus Berkenhaut) in Korea were trapped and their 31 morphometric charcters were analyzed statistically in order to determine the range of geographic variation within each species and the interspecific differences. In addition, chromosomal G-bands and C-bands were compared and the fragment patterns of mtDNA resulted from the digestion with restriction enzymes were also analyzed. Samples of black rats from six localities in Korea were similar with one another in their morphometric characters: in head and body length, length of tail vertebrae, conventional karyotype and C-bands, they are comparable to Rattus rattus tanezumi in Japan. Specimens of common rats from seven localities in Korea were similar with one another in their morphometric characters: in conventional karyotype, they are comparable to Rattus norvegicus caraco in eastern Asia. Common rats differ from black rats in their morphometric characteris, chromosomal karyotypes and mtDNA. It is confirmed that correct species name of black rat in Korea is Rattus rattus tanezumi Tempminck: species name of common rat in Korea is Rattus norvegicus caraco Pallas: the common rat is a species, which is distinct from the black rat.