• Food Science and Preservation
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• v.8 no.2
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• pp.193-198
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• 2001

Gamma irradiation at 20 kGy was apploed to salted and fermented shrimps to evaluate its possible genotoxicity. The genotoxicity of irradiated salted and fermented shrimps was evaluated by Salmonella typhimurium reversion assay, chromosomal aberration test and in vivo micronucleus assay. The results were negative in the bacterial reversion assay with S. typhimurium TA98, TA100. No mutagenicity was detected in the assay both with and without metabolic activation. In chromosomal aberration tests with CHL cells and in vivo mouse micronucleus assay, no significant difference in the incidences of chromosomal aberration and micronuclei was observed between nonirradiated and 20 kGy-irradiated salted and fermented shrimps. These results indicate that salted and fermented shrimps irradiated at 20 kGy did not show any genotoxic effects under these experimental conditions.

• Biomolecules & Therapeutics
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• v.11 no.3
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• pp.190-195
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• 2003

To assess the genotoxicity of AS6, several classical toxicological tests were performed. In Ames test, AS6 did not show any transformation of revertant with or without S-9 metabolic activating system, indicating the lack of mutagenic effect of the compound. To assess clastogenic effect, in vivo micronucleus and in vitro chromosomal aberration assays were performed using male ICR mice and Chinese hamster lung (CHL) fibroblast cells, respectively. Chromosomal aberration was not induced regardless of the presence of S-9 metabolic activating system. In addition, AS6 did not cause any increase in the incidence of micronucleated polychromatic erythrocytes at any of the dose levels, suggesting little clastogenicity in vitro or in vivo. Taken together, these results demonstrate that AS-6 has no mutagenic effect in our test system.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.817-820
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• 2006

The potential genotoxicity of methylsulfonylmethane, a crystalline organic sulfur, derived from chemically modified lignin from plants was evaluated using in vitro and in vivo assays. In the bacterial reverse mutation test using Salmonella typhimurium TA98, TA100, TA1535, and TA1538, methylsulfonylmethane did not induce any significant increase of His' revertants. In the in vitro chromosome aberration test using Chinese Hamster Lung (CHL) cells, no aberration effects were seen. In the in vivo evaluation using a micronucleus test, negative results were obtained. Accordingly, the results indicated that methylsulfonylmethane is not genotoxic and its use is unlikely to present a potential hazard.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1092-1098
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• 1999

Gamma irradiation was applied to pork for improving its hygienic quality and evaluating its possible genotoxicity. The effective dose of irradiation was 3 kGy in pork for the sterilization of all contaminated microorganisms tested. After 8 weeks of storage at 5oC, no growth of microorganisms except for psychrophile and total aerobic bacteria was observed in the more than 3 kGy irradiated pork. The genotoxicity of high dose irradiated pork(30 kGy) was evaluated by Salmonella typhimurium reversion assay, chromosomal aberration test and in vivo micronucleus assay. The results were negative in the bacterial reversion assay with S. typhimurium TA98, TA100, TA1535, TA1537. In chromosomal aberration tests with CHL cells and in vivo mouse micronucleus assay, no significant difference in the incidences of chromosomal aberration and micronuclei was seen between nonirradiated and 30 kGy irradiated porks. These results indicate that 30 kGy irradiated pork did not show any genotoxic effects under these experimental conditions.

• ALGAE
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• v.22 no.2
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• pp.69-85
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• 2007

From six reservoirs in Gyeonggi-do, we have collected the distribution and standing crop of phytoplankton since Nov. 2005 through Sep. 2006. As a result, the phytoplankton appeared totally 340 taxa belong to 7 classes, 15 orders, 5 suborders, 32 families, 4 subfamilies, 84 genera, 283 species, 43 varieties, 9 forms and 5 unidentified species. The standing crop was shown as minimum was 0.3 × 106 cells and maximum was 5,950 × 106. The relation of standing crop with TN, TP and Chl-a showed as positive. Total 12 taxa including 2 taxa of blue-green algae occurred to every seasons at six lakes, and it was thought that they distributed in mesotrophic state. Also, Achnanthes minutissima, Aulacoseira granulata, Eudorina elegans, Gloeocystis ampla, Pandorina morum, Pediastrum simplex var. duodenarium, Scenedesmus ecornis were regarded as the indicators of eutrophic state. From the estimation of LTSI and TSI, it was shown that the rest of lakes except for Idong reservoir of winter were eutrophic states.

• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.205-211
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• 1998

Participating in a multi-disciplinary oceanography program in July 1997 in the vicinity of Tokdo, we studied the distributions of bacterial abundance and production along with those of phytoplankton and heterotrophic nanoflagellates. In the euphotic zone, chlorophyll a (chl a) concentrations ranged from 0.14 to 0.52 ${\mu}$g 1$^{-1}$. Bacterial abundance in the euphotic zone (0.12-0.21 ${\times}$ 10$^9$ cells 1$^{-1}$) in the study area was quite lower than that expected from the observed chi a concentration in the marine environment. The low bacterial abundance seemed to be due to active grazing pressure on bacteria. The fraction of primary production utilized by bacteria was also low(8-12%). Interestingly, surface water temperatures were love. at stations near islands compared to an offshore station located between Ulleungdo and Tokdo and the highest values of bacterial production and chi a were found at stations near islands, strongly indicating island mass effects.

• Journal of the korean society of oceanography
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• v.31 no.1
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• pp.18-22
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• 1996

The effect of exogenous oxygen on hydrogen photoproduction was examined in the synchronously grown cells of marine Synechococcus sp. Miami BG 043511 under conditions of high cell density (0.6-0.8 mg chl-${\alpha}$ $ml^{-1}$) and high light intensity (1000 ${\mu}$E $m^{-2}$ $s^{-1}$). Hydrogen evolution after 20-h incubation did not decline under the initial oxygen concentrations up to 20%, but declined by half under 34% oxygen. 50% and 100% oxygen gas phase did not completely inhibit the hydrogen photoproduction during 40-h incubations. After 2-day pretreatment under 100% exogenous oxygen the hydrogen photoproduction capabilities were not irreversibly inhibited, which was demonstrated in the subsequent 9-day incubation under initial 0, 50 and even under 100% oxygen gas phase. This strain could be useful for developing a hydrogen photoproduction system under atmospheric oxygen concentration.

• YAKHAK HOEJI
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• v.45 no.1
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• pp.101-107
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• 2001

Green tea catechins (GTC) and its major component, (-)-epigallocatechin gallate (EGCG) were studied for their protective effects against reactive oxygen species (ROS)-induced oxidative stress. GTC and EGCG skewed the strong antioxidative effects on the lipid peroxidation of ethyl linolate with Fenton's reagent and free radical scavenging effect to DPPH radical generation. They also protected $H_2O$$_2$- or KO$_2$-induced cytotoxicity in CHL cells or mouse splenocytes. These results indicate that GTC and EGCG are capable of protecting the lipid peroxidation, flee radical generation and cytotoxicity induced by ROS. The mechanism of inhibition in ROS-induced cytotoxicity may be due to their antiofidative and free radical scavenging properties. Therefore, GTC and EGCG may be useful chemopreventive agents by protecting the free radical generation which are involved in cancer and aging.

• Journal of the East Asian Society of Dietary Life
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• v.5 no.3
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• pp.309-315
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• 1995

In this study we isolate lactic acid bacteria from kimchi, which were identified as pediococcus pentosaceus and Lactobacillus bevis by using API 50 CHL Kit, some morphological and physiological tests, The water extract of green tea(50, 100, 500, 1000ppm) inhibieted the growth of pediococcus pentosaceus and Lactobacillus brevis in broth system. Furthermore, their time were prolonged to about 4hours at 500 to 1000ppm. The leakage amount of intracellular materials and Mg++ in tested bacteria cells increased with increasing concentration of green tea water extract.

• Korean Journal of Environmental Biology
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• v.23 no.1
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• pp.57-63
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• 2005

The phytoplankton community, environmental factors, and rainfall were investigated from July to October in 2001 and 2003 on Dam site in Daechung Reservoir. The monthly average rainfall in the investigated period were 91.3 and 265.3 mm in 2001 and 2003, respectively. The maximum chlorophyll a concentration was observed higher at 131.5 ㎍ L/sup -1/ in 2003 than at 45.4 ㎍ L/sup -1/ in 2001. The cyanobacterial number in 2001 was counted up to over 200,000 cells mL/sup -1/, which was much higher than the maximum number of 49,000 cells mL/sup -1/ in 2003. The relative abundance of cyanobacteria in the phytoplankton community was about 97% in 2001 and 74% in 2003. Microcystis spp. were absolutely dominant species in 2001, while a couple of cyanobacteria such as Oscillatoria spp., Phormidium spp. Chroococcus spp. and Microcystis spp. were dominant species in 2003. Consequently, it seemed that rainfall affected the diversity of phytoplankton species and decreased the density of bloom-forming cyanobacteria.