Recent Studies on Biomethylation and Demethylation of Toxic Elements

Ridley, W. P.; Dizikes, L.; Cheh, A.; Wood, J. M.

doi:10.2307/3428449

Cited by 4 publications

(6 citation statements)

References 5 publications

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“…There are strongly held opinions, particularly with respect to the methyl donor situation in anaerobic organisms. Wood et al stated that, taking into account all of the available experimental data, "we believe that the biomethylation of arsenic by methyl-B 12 occurs in anaerobic ecosystems" (203). However, Cullen and Reimer claimed that "until strong evidence is advanced, there seems little need to invoke a different mechanism for arsenic biomethylation by bacteria from that discussed above for fungi" (75).…”

Section: Role Of Anaerobic Microorganismsmentioning

confidence: 99%

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Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Bentley

Chasteen

2002

Microbiol Mol Biol Rev

515

316

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A significant 19th century public health problem was that the inhabitants of many houses containing wallpaper decorated with green arsenical pigments experienced illness and death. The problem was caused by certain fungi that grew in the presence of inorganic arsenic to form a toxic, garlic-odored gas. The garlic odor was actually put to use in a very delicate microbiological test for arsenic. In 1933, the gas was shown to be trimethylarsine. It was not until 1971 that arsenic methylation by bacteria was demonstrated. Further research in biomethylation has been facilitated by the development of delicate techniques for the determination of arsenic species. As described in this review, many microorganisms (bacteria, fungi, and yeasts) and animals are now known to biomethylate arsenic, forming both volatile (e.g., methylarsines) and nonvolatile (e.g., methylarsonic acid and dimethylarsinic acid) compounds. The enzymatic mechanisms for this biomethylation are discussed. The microbial conversion of sodium arsenate to trimethylarsine proceeds by alternate reduction and methylation steps, with S-adenosylmethionine as the usual methyl donor. Thiols have important roles in the reductions. In anaerobic bacteria, methylcobalamin may be the donor. The other metalloid elements of the periodic table group 15, antimony and bismuth, also undergo biomethylation to some extent. Trimethylstibine formation by microorganisms is now well established, but this process apparently does not occur in animals. Formation of trimethylbismuth by microorganisms has been reported in a few cases. Microbial methylation plays important roles in the biogeochemical cycling of these metalloid elements and possibly in their detoxification. The wheel has come full circle, and public health considerations are again important

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Section: Role Of Anaerobic Microorganismsmentioning

confidence: 99%

“…The possible chemistry for nonenzymatic and enzyme-catalyzed methyl transfers from methylcobalamin to arsenic has been discussed in detail (83,196,203,209,210,250). There are strongly held opinions, particularly with respect to the methyl donor situation in anaerobic organisms.…”

Section: Role Of Anaerobic Microorganismsmentioning

confidence: 99%

Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Bentley

Chasteen

2002

Microbiol Mol Biol Rev

515

316

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“…Recent gernane publications bearing on sources, transport, and alterations of arsenic published as part of the Proceedings of the International Conference on Environmental Arsenic, Fort Lauderdale, Fla., October 5-8, 1976 include: industrial contribu- August 1981 tion of As to the environment (52); emissions in Sweden and their reductions (53); occurrence and transformation in the marine environment (54); environmental mobility (55); biomethylation and demethylation (56); fate in different environmental substrates (57); occurrence and distribution in soils and plants (58) and implications of inorganic/organic interconversion on fluxes of As in marine food webs (59). Other recent relevant publications with focus as above include: the National Academy of Sciences report on arsenic (60); environmental mobility of arsenic (61); effects of microcosm size and substrate type on aquatic microcosm behavior and arsenic transport (62); cycle in natural waters (63); distribution and speciation of arsenic in natural waters and marine algae (64); biosynthesis and release of organoarsenic compounds by marine algae (65); accumulation of arsenic in sediments of lakes treated with sodium arsenite (66); and As in marine and aquatic environments (67).…”

Section: Arsenicmentioning

confidence: 99%

“…The biomethylation of arsenic by methyl-B12 occurs in anaerobic ecosystems. The volatile species arsine, dimethylarsine, and trimethylarsine will be released into the aerobic environment at the sediment/water, water/air, or soil/air interface (56). These alkylated arsenic compounds are slowly oxidized in air and water to give steady state concentrations of methylated arsenic compounds of higher oxidation state.…”

mentioning

confidence: 99%

Sources, Transport and Alterations of Metal Compounds: An Overview. I. Arsenic, Beryllium, Cadmium, Chromium, and Nickel

Fishbein¹

1981

Environmental Health Perspectives

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An overview is presented of the current state of knowledge of the salient aspects of the sources, transport, and alterations of arsenic, beryllium, cadmium, chromium, and nickel. This information is considered vital for a better assessment of the scope of potential human hazard to these ubiquitous toxicants and their compounds. Stress is focused on both natural and industrial activities, particularly on the latter's projected trends. Increasing use patterns per se of most of these metals, as well as aspects of waste disposal and the anticipated increased combustion of fossil fuels for power generation and space heating (particularly in the United States), are major causes of potential health concern. Additionally, attention is drawn to the need for increased research to fill the gaps in our knowledge in these vital areas, all in the hope of permitting a more facile identification and quantification of the potential hazard to exposure to these agents.

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“…Microbes have also been shown to demethylate mercury in sediments (73), which only serves to further confuse the issue of the source of elevated methylmercury in fish tissues. Arsenic, selenium, lead, and tin are examples of other toxic elements that undergo methylation (74).…”

Section: Biological Transformationsmentioning

confidence: 99%

Transport and transportation pathways of hazardous chemicals from solid waste disposal.

Hook¹

1978

Environ Health Perspect

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To evaluate the impact of hazardous chemicals in solid wastes on man and other organisms, it is necessary to have information about amounts of chemical present, extent of exposure, and chemical toxicity. This paper addresses the question of organism exposure by considering the major physical and biological transport pathways and the physicochemical and biochemical transformations that may occur in sediments, soils, and water. Disposal of solid wastes in both terrestrial and oceank environments is considered. Atmospheric transport is considered for emissions from incineration of solid wastes and for wind resuspension of particulates from surface waste deposits.Solid wastes deposited in terrestrial environments are subject to leaching by surface and ground waters. Leachates may then be transported to other surface waters and drinking water aquifers through hydrologic transport. Leachates also interact with natural organic matter, clays, and microorganisms in soils and sediments. These interactions may render chemical constituents in leachates more or less mobile, possibly change chemical and physical forms, and alter their biological activity. Oceanic waste disposal practices result in migration through diffusion and ocean currents. Surface area-to-volume ratios play a major role in the initial distributions of chemicals in the aquatic environment. Sediments serve as major sources and sinks of chemical contaminants. Food chain transport in both aquatic and terrestrial environments results in the movement of hazardous chemicals from lower to higher positions in the food web. Bioconcentration is observed in both terrestrial and aquatic food chains with certain elements and synthetic organics. Bioconcentration factors tend to be higher for synthetic organics, and higher in aquatic than in terrestrial systems. Biodilution is not atypical in terrestrial environments. Synergistic and antagonistic actions are common occurrences among chemical contaminants and can be particularly important toxicity considerations in aquatic environments receiving runoff from several terrestrial sources.

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Recent Studies on Biomethylation and Demethylation of Toxic Elements

Cited by 4 publications

References 5 publications

Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Sources, Transport and Alterations of Metal Compounds: An Overview. I. Arsenic, Beryllium, Cadmium, Chromium, and Nickel

Transport and transportation pathways of hazardous chemicals from solid waste disposal.

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