• 한국환경농학회지
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• 제33권2호
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• pp.129-133
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• 2014

BACKGROUND: This study was performed for selecting yeast mutants with a high tolerance for targeted metals, and determining whether yeasts strains tolerant to multiple heavy metals could be induced by sequential adaptations. METHODS AND RESULTS: A mutant yeast strain tolerant to the heavy metals cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) was selected by sequential elevated exposures to each metal with intermittent mutant isolation steps. A Cd-tolerant mutant was isolated by growing yeast cells in media containing $CdCl_2$ concentrations that were gradually increased to 1 mM. Then the Cd-tolerant mutant was gradually exposed to increasing levels of $CuCl_2$ in growth media until a concentration of 7 mM was reached, thus generating a strain tolerant to both Cd and Cu. In the subsequent steps, this mutant was exposed to $NiCl_2$ (up to 8 mM), and a resultant isolate was further exposed to $ZnCl_2$ (up to 60 mM), allowing the derivation of a yeast mutant that was simultaneously tolerant to Cd, Cu, Ni, and Zn. CONCLUSION: This method of inducing tolerance to multiple targeted heavy metals in yeast will be useful in the bioremediation of heavy metals.

• 한국환경농학회지
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• 제27권4호
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• pp.389-394
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• 2008

The ecophysiological changes occurring upon cold stress were studied using cold tolerant transgenic and wild-type tobacco plants. In a previous study, cold tolerance in tobacco was induced by the introduction of a gene encoding the zinc finger transcription factor, PIF1. Gas-exchange measurements including net photosynthesis and stomatal conductance were performed prior to, in the middle of, and after a cold-stress treatment of $1{\pm}2^{\circ}C$ for 96 h in each of the four seasons. In both transgenic and wild-type plants, gas-exchange parameters were severely decreased in the middle of the cold treatment, but had recovered after 2-3 h of adaptation in a greenhouse. Most t-test comparisons on gas-exchange measurements between the two plant types did not show statistical significance. Wild-type plants had slightly more water-soaked damage on the leaves than the transgenic plants. A light-response curve did not show any differences between the two plant types. However, the curve for assimilation-internal $CO_2$ in wild-type plants showed a much higher slope than that of the PIF1 transgenic plants. This means that the wild-type plant is more capable of regenerating Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and has greater electron transport capacity. In conclusion, cold-resistant transgenic tobacco plants demonstrated a better recovery of net photosynthesis and stomatal conductance after cold-stress treatment compared to wild-type plants, but the ecophysiological recoveries of the transgenic plants were not statistically significant.

• Journal of Microbiology and Biotechnology
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• 제22권11호
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• pp.1557-1567
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• 2012

Glutathione reductase (GR, E.C. 1.6.4.2) is an important enzyme that reduces glutathione disulfide (GSSG) to a sulfydryl form (GSH) in the presence of an NADPH-dependent system. This is a critical antioxidant mechanism. Owing to the significance of GR, this enzyme has been examined in a number of animals, plants, and microbes. We performed a study to evaluate the molecular properties of GR (OsGR) from rice (Oryza sativa). To determine whether heterologous expression of OsGR can reduce the deleterious effects of unfavorable abiotic conditions, we constructed a transgenic Saccharomyces cerevisiae strain expressing the GR gene cloned into the yeast expression vector p426GPD. OsGR expression was confirmed by a semiquantitative reverse transcriptase polymerase chain reaction (semiquantitative RT-PCR) assay, Western-blotting, and a test for enzyme activity. OsGR expression increased the ability of the yeast cells to adapt and recover from $H_2O_2$-induced oxidative stress and various stimuli including heat shock and exposure to menadione, heavy metals (iron, zinc, copper, and cadmium), sodium dodecyl sulfate (SDS), ethanol, and sulfuric acid. However, augmented OsGR expression did not affect the yeast fermentation capacity owing to reduction of OsGR by multiple factors produced during the fermentation process. These results suggest that ectopic OsGR expression conferred acquired tolerance by improving cellular homeostasis and resistance against different stresses in the genetically modified yeast strain, but did not affect fermentation ability.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2010년도 정기총회 및 추계학술발표회
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• pp.14-14
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• 2010

Vitamin C (ascorbic acid) is an essential component for collagen biosynthesis and also for the proper functioning of the cardiovascular system in humans. Unlike most of the animals, humans lack the ability to synthesize ascorbic acid on their own due to a mutation in the gene encoding the last enzyme of ascorbate biosynthesis. As a result, vitamin C must be obtained from dietary sources like plants. In this study, we have developed two different kinds of transgenic potato plants (Solanumtuberosum L. cv. Taedong Valley) overexpressing strawberry GalUR and mouse GLoase gene under the control of CaMV 35S promoter with increased ascorbic acid levels. Integration of the these genes in the plant genome was confirmed by PCR and Southern blotting. Ascorbic acid(AsA) levels in transgenic tubers were determined by high-performance liquid chromatography(HPLC). The over-expression of these genes resulted in 2-4 folds increase in AsA intransgenic potato and the levels of AsA were positively correlated with increased geneactivity. The transgenic lines with enhanced vitamin C content showed enhanced tolerance to abiotic stresses induced by methyl viologen(MV), NaCl or mannitol as compared to untransformed control plants. The leaf disc senescence assay showed better tolerance in transgenic lines by retaining higher chlorophyll as compared to the untransformed control plants. Present study demonstrated that the over-expression of these gene enhanced the level of AsA in potato tubers and these transgenics performed better under different abiotic stresses as compared to untransformed control. We have also investigated the mechanism of the abiotic stress tolerance upon enhancing the level of the ascorbate in transgenic potato. The transgenic potato plants overexpressing GalUR gene with enhanced accumulation of ascorbate were investigated to analyze the antioxidants activity of enzymes involved in the ascorbate-glutathione cycle and their tolerance mechanism against different abiotic stresses under invitro conditions. Transformed potato tubers subjected to various abiotic stresses induced by methyl viologen, sodium chloride and zinc chloride showed significant increase in the activities of superoxide dismutase(SOD, EC 1.15.1.1), catalase, enzymes of ascorbate-glutathione cycle enzymes such as ascorbate peroxidase(APX, EC 1.11.1.11), dehydroascorbate reductase(DHAR, EC 1.8.5.1), and glutathione reductase(GR, EC 1.8.1.7) as well as the levels of ascorbate, GSH and proline when compared to the untransformed tubers. The increased enzyme activities correlated with their mRNA transcript accumulation in the stressed transgenic tubers. Pronounced differences in redox status were also observed in stressed transgenic potato tubers that showed more tolerance to abiotic stresses when compared to untransformed tubers. From the present study, it is evident that improved to lerance against abiotic stresses in transgenic tubers is due to the increased activity of enzymes involved in the antioxidant system together with enhanced ascorbate accumulated in transformed tubers when compared to untransformed tubers. At moment we also investigating the role of enhanced reduced glutathione level for the maintenance of the methylglyoxal level as it is evident that methylglyoxal is a potent cytotoxic compound produced under the abiotic stress and the maintenance of the methylglyoxal level is important to survive the plant under stress conditions.

• 한국식품조리과학회지
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• 제9권3호
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• pp.195-197
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• 1993

This study investigated the contamination of trace metals on edible visceras : tongue, intestine, lung, testis, gira, blood, liver, stomach, and kidney. The edible visceras were selected at random from ten markets in Seoul. The edible visceras underwent freeze drying prior to analysis. The contents of arsenic, cadmium, cobalt, chromium, copper, magnases, molybdenum, lead, and zinc were detected by ICP(Inductively Coupled Plasma Spectrophotometry). The results showed that the levels of trace metals in all the samples fall within the tolerance limit and cadmium in lung tended to be high(>0.1 ppm). Therefore, we may study and investigate continuously on the food contamination of heavy metals for the public health.

• 미생물학회지
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• 제24권1호
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• pp.57-61
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• 1986

폐수중에 함유된 카드뮴을 미생물학적인 방법으로 정화하기 위한 기초 연구로서 아연 광산에서 고도 카드뮴 내성 효모 B-7을 분리하여 동정한 바 Hansenula anomala B-7 또는 그 유연끌으로 밝혀졌다. 이 효모는 농도 구배 한천 명판법에 의하여 $2,700{\mu}g/ml$의 카드뮴 농도에서도 내성을 나타내므로 고도 내성균으로 분류되었고 $1,000{\mu}g/ml$의 고농도 카드뮴 함유 액체 배지에서도 생육이 가능함을 확인하였다.

• 문화기술의 융합
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• 제5권4호
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• pp.373-378
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• 2019

해양지역에서는 토양의 염 농도가 증가하고 내륙지역은 중금속 오염으로 식물의 피해가 따라서 증가한다. 내륙의 산업 발달 지역에서는 Co, Ni, Zn, 등 중금속이 축적되어 제거하거나, 내성을 갖은 식물의 유전자원 연구가 절실히 요구되고 있다. 앞의 두 가지 문제점은 공히 식물 뿌리에 스트레스를 야기하기에 가능성 있는 식물을 찾기에 과학자들이 많은 노력을 해오고 있다. 본 연구에서는 내염식물로 알려진 것으로 해안가 근처에서 채집 되어진 섬갯장대(Arabis stelleri var. japonica)의 종자를 발아하여 사용하였다. 동일한 과이면서 모든 유전자가 밝혀졌고, 표본식물인 애기장대 종자를 실험재료로 사용하여 실험실 배양 조건 하에서 성장발육과 내성을 비교 연구하였다. 그 결과 250 uM Nickle과 cobalt에서 3배 정도 내성을 나타내었고,1mM 아연에서는 4배 이상의 내성을 섬갯장대에서 나타내었다. Na염에 대한 내성은 50mM 농도에서 20%이상 발육이 증가하여서 중금속과 염농도에 내성을 보였다. 세포내 기작을 연구하기 위한 준비로서 Na 이온의 체내 축적을 측정하였다. 그 결과 내성을 갖은 섬갯장대 경엽부에서 더욱 감소하는 결과를 보였다. 이는 측적하는 기작보다는 배출하는 유전자의 활성이 중요하다고 사료된다.

• Journal of Preventive Medicine and Public Health
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• 제24권3호
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• pp.287-304
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• 1991

Tolerance to several toxic effects of cadmium, including lethality has been shown following pretreatment with cadmium and zinc. This study was designed to determine if tolerance also develops to Cd-induced hepatotoxicityandrenaltoxicity. Three groups of rats (A, B, C), each consisting of 16 rats, were studied and each group was divided into four subgroups (1, 2, 3, 4), 4 rats for each subgroup. Rats were subcutaneously pretreated with saline (A), $CdCl_2$ (0.5 mg/kg, B), and $ZnCl_2$ (13.0 mg/kg, C) during time periods of $1{\sim}6$ weeks. At the end of the period, rats were challenged with $CdCl_2$ (3.0, 6.0 and 9.0 mg/kg, ip). After giving the challenge dose, cadmium and metallothionein (MT) concentrations were determined and also observed the histologic change in liver and kidney. The concentration of cadmium in liver and kidney increased dose-dependently to the challenge dosage. These da indicate the kidney is a major target organ of chronic cadmium poisoning, and suggest that cadmium induced hepatic injury, via release of Cd-MT, may play an important role in the nephrotoxicity observed in response to long-term exposure to cadmium. In addition, histologic examination of group $A_2,\;A_3\;and\;A_4$ revealed moderate to severe cadmium toxicity, evidenced by infiltration of inflammatory cells, cell swelling, pyknosis, enlarged sinusoids and necrosis in liver, and tubule cell necrosis and degeneration in kidney. However, MT concentrations in liver and kidney were increased by the pretreatment of $CdCl_2$ and $ZnCl_2$, and their morphological findings were not significantly changed, comparing with control group. Higher MT concentration in liver and kidney observed in the pretreated groups constitutes a plausible explanation of the protective effects of pretreatment against the cadmium toxicity after challenge dosing.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권5호
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• pp.35-44
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• 2014

In this study, the bio-phytoremediation and phytoremediation technologies were applied to the soils contaminated with total petroleum hydrocarbons (TPH) and heavy metals to evaluate the remediation efficacy from May 2012 to December 2013. Poplar (Populus bonatii Levl.) and Sun Hemp (Crotalaria juncea L.) were selected and planted in phytoremediation practice. These plants were also utilized in the bio-phytoremediation practice, with the addition of earthworm (Eisenia fetida) and petroleum-degrading bacteria (Pseudomonos sp. NKNU01). Furthermore, physiological characteristics, such as photosynthesis rate and maximal photochemical yield, of all testing plants were also measured in order to assess their health conditions and tolerance levels in adverse environment. After 20 months of remedial practice, the results showed that bio-phytoremediation practice had a higher rate of TPH removal efficacy at 30-60 cm depth soil than that of phytoremediation. However, inconsistent results were discovered while analyzing the soil at 100 cm depth. The study also showed that the removal efficiency of heavy metals was lower than that of TPH after remediation treatment. The results from test field tissue sample analysis revealed that more Zinc than Chromium was absorbed and accumulated by the tested plants. Plant height measurements of Poplar and Sun Hemp showed that there were insignificant differences of growth between the plants in remediation plots and those in the control plot. Physiological data of Poplar also suggested it has higher tolerance level toward the contaminated soils. These results indicated that the two testing plants were healthy and suitable for this remediation study.

• Journal of Microbiology and Biotechnology
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• 제31권3호
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• pp.419-428
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• 2021

To efficiently recycle GH78 thermostable rhamnosidase (TpeRha) and easily separate it from the reaction mixture and furtherly improve the enzyme properties, the magnetic particle Fe3O4-SiO2-NH2-Cellu-ZIF8 (FSNcZ8) was prepared by modifying Fe3O4-NH2 with tetraethyl silicate (TEOS), microcrystalline cellulose and zinc nitrate hexahydrate. FSNcZ8 displayed better magnetic stability and higher-temperature stability than unmodified Fe3O4-NH2 (FN), and it was used to adsorb and immobilize TpeRha from Thermotoga petrophilea 13995. As for properties, FSNcZ8-TpeRha showed optimal reaction temperature and pH of 90℃ and 5.0, while its highest activity approached 714 U/g. In addition, FSNcZ8-TpeRha had better higher-temperature stability than FN. After incubation at 80℃ for 3 h, the residual enzyme activities of FSNcZ8-TpeRha, FN-TpeRha and free enzyme were 93.5%, 63.32%, and 62.77%, respectively. The organic solvent tolerance and the monosaccharides tolerance of FSNcZ8-TpeRha, compared with free TpeRha, were greatly improved. Using naringin (1 mmol/l) as the substrate, the optimal conversion conditions were as follows: FSNcZ8-TpeRha concentration was 6 U/ml; induction temperature was 80℃; the pH was 5.5; induction time was 30 min, and the yield of products was the same as free enzyme. After repeating the reaction 10 times, the conversion of naringin remained above 80%, showing great improvement of the catalytic efficiency and repeated utilization of the immobilized α-L-rhamnosidase.