• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.323-329
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• 2018

In Escherichia coli, the transcription of genes related to metal homeostasis is activated by the presence of target metals. The promoter regions of those genes can be fused with reporter genes to generate whole-cell bioreporters (WCBs); these organisms sense the presence of target metals through reporter gene expression. However, the limited number of available promoters for sensing domains restricts the number of WCB targets. In this study, we have demonstrated an alternative method to generate novel WCBs, based on the notion that since the sensing mechanisms of WCBs are related to metal transportation systems, their properties can be modulated by disrupting metal homeostasis. Mutant E. coli strains were generated by deleting the znt-operon genes zntA, which encodes a zinc-export protein, and zntR, which encodes a znt-operon regulatory protein, to investigate the effects on the metal-sensing properties of WCBs. Deletion of zntA increased the sensitivity but abolished the selectivity of cadmium-sensing WCBs, whereas arsenic-sensing WCBs gained sensitivity toward cadmium. When zntR was deleted, cadmium-sensing WCBs lost the ability to detect cadmium, and this was recovered by introducing exogenous zntR. In addition, the metal-binding site of ZntR was genetically engineered to modulate metal selectivity. This study provides a valuable platform for the development of novel E. coli-based WCBs.

• Environmental Analysis Health and Toxicology
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• v.19 no.4
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• pp.389-399
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• 2004

Metallothionein (MT), a small protein molecule which can bind or release metal ions, is involved in the regulation of cellular metal homeostasis. This study was investigated the accumulation of cadmium in blood, tissue (liver, kidney and brain), and the effect of cadmium on several key genes (MT-I, MT-II, ZnT-1) in zinc metabolism in the mouse. Mouses weighing 20∼25 g were randomly assigned to control and cadmium treated group (Cd group). Cd group was intraperitoneally injected with cadmium 2, 4, 8 mg/kg and control group was administerd with saline. Mouses of each group were sacrificed by decapitation 4 hours after the administration of cadmium. Cadmium contents in blood, liver, kidney and brain were increased by a dose-dependent manner. Accumulation of cadmium was mainly occurred in liver and kidney. Induction of MT-I and MT-II protein was increased, but ZnT-1 expression was decreased in a dose-dependent manner by the treatment of 2∼8 mg/kg cadmium. These results suggested that cadmium can be transported to brain and alter the expression of several key genes in zinc homeostasis.

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.30-35
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• 1994

A varient strain of budding yeast, Hansenula anomala B-7 which had been identified to be highly resistant to cadmium ions, were observed by transmission electron microscopy. It was shown that the cells accumulated excess amounts of cadmium ions throughout inside the cell rather than on the cell surface. The cell growth in response to cadmium or heat shock stress has also been investigated. It was observed that the cells precultured in the presence of 500 $\mu$ g/ml of Cd ions grew slower than those precultured at 1, 000 $\mu$ g/ml of the metal ions, when they were cultivated in the media containing 1, 000 $\mu$g/ml of the metal ions. Heat shock, however, stimulated the cell growth transiently, when the cells were allowed to grow in the presence of 1, 000 $\mu$g/ml of the metal ions. But the cells given heat shock for more than 100 min received permanent damage to growth. Effects of both stresses on budding rate was also examined. It revealed that the stresses did not change the budding ratio much, which was contradictory to that observed from the same budding yeast, Saccharomyces cerevisiae. Furthermore, the cells treated with 1, 000 $\mu$g/ml of the metal ions not only induced, but also switched off the expression of several new proteins. Some of the cadmium stress-inducible proteins were estimated to be also induced by heat shock stress.

• Korean Journal of Microbiology
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• v.31 no.4
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• pp.300-305
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• 1993

Neurospora crassa accumulated cadmium. iron, manganese and lead in the mycelium. The growth of N. crassa was inhibited in the presence of cadmium but not in the presence of iron or manganese. In the presence of lead. the growth of N. crassa was accelerated. In the presence of cadmium. mycelium became thick and a conidiospore grew into a mycelial ball instead of normal threadlike gro~1h. Each metal wa'i accumulated in different subcellular organelles bound to protein and induced different proteins.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.489-494
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• 2007

Transcriptional modulation of metallothionein (MT) during acute metal exposures (cadmium, copper or zinc) was examined in fry of Hemibarbus mylodon, a threatened fish species in Korean peninsula. Viability of H. mylodon fry was most affected by copper exposure (up to 79% of mortality at 1 ppm for 48 hours) and considerably by cadmium exposure (21 to 54% of mortality). On the other hand, Zn showed the least adverse effect on the viability (0 to 13% of mortality) of this species. Based on the semi-quantitative RT-PCR analysis, the stimulation of MT mRNA in response to metal exposures followed generally in a dose-dependent fashion where cadmium was the most potent inducer for the induction of MT transcripts in fry (up to more than 5-fold) while the lowest response was observed in zinc-exposed group (2-fold at maximum). From the exposure using environmentally realistic doses of cadmium (0 to 0.05 ppm for 24 hours), MT expression at mRNA level was also sensitively modulated toward upregulation up to more than 3-fold as relative to non-exposed control. Results from the present study would be a good basis for understanding the adaptive capacity and stress physiology of this endangered fish species during metal pollution.

• Journal of Environmental Health Sciences
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• v.46 no.3
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• pp.297-311
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• 2020

Objective: We compared the level of blood cadmium exposure with health impacts by using data from a survey of residents near an abandoned mine and a national health survey. Methods: For this study, we used data from 7,046 individuals who participated in the Health Effects Survey of Abandoned Metal Mines (AMS, 2008-2011) and 6,871 individuals who participated in the Korea National Health and Nutrition Examination Survey IV-VI (KNHANES, 2008-2013). To evaluate the health impacts, the quartiles (S1 to S4) were classified according to blood cadmium concentration, and then the odds ratios of S2 to S4 over S1 for exceeding the reference values of renal function, blood pressure, and bone density were compared. Similarly, the odds ratio of AMS over KNHANES was confirmed. Results: In the AMS, adjusted for general characteristics, the geometric mean of blood cadmium concentration was 1.34 ㎍/L, which was statistically significantly higher than that of the KNHANES 1.22 ㎍/L (p<0.001). In the integrated data of AMS and KNHANES, the estimated odds ratio of S4 over S1 for exceeding the reference value was found to be 1.70 for serum creatinine, 1.71 for hypertension, and a T-score 2.02 for the tarsal bone. They were all statistically significant. Conclusion: Residents around abandoned metal mines had a higher blood cadmium concentration than the general population, and the odds for exceeding the reference values were higher for some health indicators. Continuous biomonitoring should be conducted for vulnerable areas such as around abandoned metal mines, and measures to reduce cadmium exposure and management of chronic diseases are needed.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.422-427
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• 1995

In a stream of water sample, trace metal ions are quantitatively coprecipitated with Indium hydroxide and filtered. The filtered precipitate is continuously dissolved in 3 M nitric acid and introduced to ICP directly. The lead, cadmium, and copper are concentrated more than 10-fold and determined with ICP-AES at a sampling frequency of 10/hour. The detection limits are 2.89, 1.43,0.52 ppb for lead, cadmium, and copper respectively. Recoveries of lead, cadmium, and copper are 98.7, 94.3, and 104.5% respectively. The RSD values for three elements are about 3-5% currently.

• Environmental Engineering Research
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• v.20 no.1
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• pp.41-50
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• 2015

The cyanobacterium Anabaena doliolum Ind1 isolated from a coal mining site was tested for removal of cadmium at optimum pH 7.0 and temperature $25^{\circ}C$. The organism recorded high percentage of metal removal (92-69%) within seven days of exposure to 0.5-2.0 ppm cadmium. Biosorption onto the cell surface was the primary mode of metal removal. Fourier transform infrared spectroscopy (FTIR) established hydroxyl, amides, carboxyl, sulphate and carbonyl groups to be the major functional groups on the cell surface involved in cadmium binding. Cellular ultrastructure and a range of vital physiological processes (i.e., photosynthetic pigments, respiration, photosynthesis, heterocyst frequency and nitrogenase activity) remained unaffected upon 0.5 ppm treatment; higher concentrations of cadmium exerted visible adverse effects. Amongst the five photosynthetic pigments tested, phycocyanin was the most targeted pigment (inhibition was 15-89%). Both respiration and photosynthetic activities were inhibited by cadmium with more severe effect seen on respiration. 2.0 ppm cadmium exposure also had drastic negative effect on nitrogenase activity (87% decreased).

• Journal of Nutrition and Health
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• v.29 no.9
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• pp.958-970
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• 1996

This study was performed to investigate the effect of dietary calcium level on cadmium and lead toxicity in rats. Fifty-four male rats of Sprague-Dawely strain weighing 152$\pm$12g were blocked into 9 groups according to body weight, and were raised for 30 days. Nine experimental diets different with cadmium(0%, 0.04%), lead (0%, 0.071%) and calcijm(0.5%, 1.0%, 1.5%) levels were prepared. The results are summarized as follow. Weight gain, F.E.R.(food efficiency ratio), and weights of liver, kidney and femur were lower in cadmium exposed groups than those of heavy metal free groups. Weight gain F.E.R. and ash weight of lead groups were lower than those of heavy metal free groups. But, these were increased with increasing dietary calcium level. Cadmium and lead concentrations in blood, liver, kidney and femur were lower in rats fed 1.5% calcium than 0.5% calcium diet. Fecal cadmium and lead excretions were remarkably increased in 1.5% calcium groups, and cadmium and lead retention rates were decreased in 1.5% calcium groups. Metallothionein concentrations in liver, kidney and small intestine were higher in rats exposed to cadmium and lead. Calcium content in blood, femur and daily urinary and fecal calcium excretion were decreased by cadmium and lead additions, and increased in 1.5% calcium groups. Creatinine clearance were decreased with cadmium administratino and calcium addition. In conclusion, weight gain and organ weights were decreased with cadmium or lead administration. But, cadmium administration was more toxic than lead adminstration. Cadmium or lead toxicity was alleviated by increasing dietary calcium level. Especially, lead toxicity was alleviated in proportion to dietary calcium level.

• Proceedings of the PSK Conference
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• 2003.10a
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• pp.73-73
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• 2003

The heavy metal cadmium is a xenobiotic toxicant of environmental and occupational concern and it has been classified as a human carcinogen. Inhalation of cadmium has been implicated in the development of emphysema and pulmonary fibrosis, but, the detailed mechanism by which cadmium induces adverse biological effects is not yet known. Therefore, we undertook the investigation of genes that are induced after cadmium exposure to illustrate the mechanism of cadmium toxicity. (omitted)