title: Effect of inorganic and organic ligands on the bioavailability of methylmercury as determined by using a mer-lux bioreporter.
abstract: A mer-lux bioreporter was constructed to assess the bioavailability of methylmercury [CH(3)Hg(II)] in Escherichia coli. The bioreporter was shown to be sensitive, with a detection limit of 2.5 nM CH(3)Hg(II), and was used to investigate the effects of chlorides, humic acids, and thiols on the bioavailability of CH(3)Hg(II) in E. coli. It was found that increasing the concentration of chlorides resulted in an increase in CH(3)Hg(II) bioavailability, suggesting that there was passive diffusion of the neutral complex (CH(3)HgCl(0)). Humic acids were found to reduce the bioavailability of CH(3)Hg(II) in varying degrees. Complexation with cysteine resulted in increased bioavailability of CH(3)Hg(II), while assays with equivalent concentrations of methionine and leucine had little or no effect on bioavailability. The mechanism of uptake of the mercurial-cysteine complexes is likely not passive diffusion but could result from the activities of a cysteine transport system. The bioavailability of CH(3)Hg(II) decreased with increasing glutathione concentrations.
authors.affiliation: Department of Marine Sciences, University of Connecticut, Groton, Connecticut, USA.
authors.forename: Udonna
authors.initials: U
authors.lastname: Ndu
authors.forename: Robert P
authors.initials: RP
authors.lastname: Mason
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.forename: Senjie
authors.initials: S
authors.lastname: Lin
authors.forename: Pieter T
authors.initials: PT
authors.lastname: Visscher
mesh_terms: D001682:Biological Availability; D002712:Chlorides / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism*; D017930:Genes, Reporter; D006812:Humic Substances; D008024:Ligands; D008156:Luciferases / Q000032:analysis / Q000235:genetics; D008767:Methylmercury Compounds / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D002712:Chlorides; D006812:Humic Substances; D008024:Ligands; D008767:Methylmercury Compounds; D013438:Sulfhydryl Compounds; D008156:Luciferases