Methylmercury resistance

Miura, K., and T.W. Clarkson. 1993. Reduced methylmercury accumulation in a methylmercury resistant rat pheochromocytoma PC12 cell line. Toxicol. Appl. Pharmacol. 118(l) 39-45. 

Increasing glutathione levels were positively correlated with increasing methylmercury resistance of rat PC 12 cells and decreasing methylmercury accumulations. In that study. 

Miura K, Clarkson TW, Ikeda K, Naganuma A, Imura N (1994a) Establishment and characterization of methylmercury-resistant PC12 cell line. Environ Health Perspectives (in press)... 

Baldi, R, Parati, R, and Filipelli, M. (1993) Methylmercury resistance in Desulfovibrio desulfuricans strains in relation to methylmercury degradation. Appl. Environ. Microbiol, 59,2479-85. 

In Hg-resistant bacteria that are resistant to organic forms of Hg such as phenylmercuric acetate and methylmercury chloride, lyases are involved in the fission of the C-Hg to form Hg + and benzene or methane, and the enzyme has been partly purified (Schottel 1978). The Hg + may then be reduced to nontoxic Hg°. The situation under anaerobic conditions for sulfate-reducing bacteria is complicated by the possibility of both methylation and demethylation in the same strain (Pak and Bartha 1998), plausibly by operation of the acetyl-CoA pathway (Choi et al. 1994 Ekstrom et al. 2003). Under anaerobic conditions, demethylation, though not methylation, has been reported for a methanogen (Pak and Bartha 1998). 

Bizily, S. P., Rugh, C. L., Summers, A. O., and Meagher, R. B., 1999, Phytoremediation of methylmercury pollution merB expression in Arabidopsis thaliana confers resistance to organomercurials, Proc. Natl. Acad. Sci. U.S.A. 96 6808-6813. 

A method for detecting methylmercury in biological samples by its enzymatic conversion to methane is an alternative biological technique for methylmercury or other organomercurial analyses (Baldi and Filippelli 1991). Pseudomonasputida strain FBI, a broad spectrum mercury-resistant strain, is able to enzymatically convert methylmercury to Hg° and methane either in whole cell or in cell-free extracts. GC/FID was used to determine methane produced by the biological derivatization of methylmercury. The detection limit was 15 ng of methylmercury extracted from 1 g of biological tissue. The coefficient of variation was 1.9%. Chemical interferences are negligible in the enzymatic determination of methyl-... 

Decomposition of methylmercury can be achieved by numerous mercury-resistant bacteria via cleavage of the mercury carbon bond and conversion of Hg to give methane and Hg(0), as considered in Section 12.13.4. Genetic aspects of mercury resistance have been reviewed. Other routes to decomposition include an oxidative route... 

Some fish populations have developed a resistance to methylmercury, but only in the gametes and embryonic stage. Thus, eggs of the mummichog (Fundulus heteroclitus), an estuarine cyprinodontiform fish, from a mercury-contaminated creek, when compared to a reference site, were more than twice as... 

Mercury-tolerant strains of bacteria and protozoa have been reported. Mercury-resistant strains of bacteria are common. In Chesapeake Bay, for example, at least 364 strains of bacteria that were isolated were resistant to HgCb. Most were pseudomonads, and almost all were from seven genera. Other groups of bacteria known to materially influence mercury fluxes in saline waters include strains of Escherichia coli that convert Hg + to Hg, and strains of anaerobic methanogenic bacteria that enhance the transfer of methylcobalamin to Hg + under mild reducing conditions. Some mercury-resistant strains were reported to degrade petroleum as well. Mercury-resistant strains of bacteria have been recommended as bioindicators of environmental mercury contamination and as markers of methylmercury in biological samples. The mercury-resistant... 

Enzymatic detoxification was determined to be the major resistance mechanism in all species of mercury-resistant bacteria. For example, mercuric reductase was essential for volatilization of Hg from Hg + and various organomercurial hydrolases were responsible for volatilization of methane (CH4) from methylmercury, for ethane (C2H4) from ethylmercury, and for benzene from phenylmercury. Minamata Bay bacterial isolates can also volatilize Hg from added inorganic and organic mercurials. Genes which govern the chemistry of mercury detoxification were abundant in bacteria found in Minamata Bay and other mercury-polluted sites these genetic strains of mercury-resistant bacteria show promise for bioremediation of mercury pollution. 

Aratidopsis Plants Expressing MerB Confer Strong Resistance to Methylmercury... 

Figure 2. MerB expressing Arabidopsis resistant to methylmercury. Seeds from wild-type control (RLD), merA, and merB expressing lines were germinated on 1/2 MS (Murashige and Skoog) medium without (left) and with 2 pM methylmercury and grown for three weeks. Only merB expression allows normal...

Lakowicz, J. R. and Anderson, C. I., 1980. Permeability of lipid bilayers to methylmercury chloride. Chem. Biol Interact. 30, 309-323. Ludwig, L. E., 1974. Formulation of mildew-resistant coatings. J. Coat. Technol 46(594), 31-39. 

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