Hexavalent chromium [Cr(VI)] compounds are established human lung carcinogens. The carcinogenicity of Cr(VI) is related to its solubility, with the most potent carcinogens being the insoluble particulate Cr(VI) compounds. However, it remains unknown why particulate Cr(VI) is more carcinogenic than soluble Cr(VI). One possible explanation is that particulates may provide more chronic exposures t...

The chromate resistance determinant of Pseudomonas aeruginosa plasmid pUM505 was cloned into broad-host-range vector pSUP104. The hybrid plasmid containing an 11.1-kilobase insert conferred chromate resistance and reduced uptake of chromate in P. aeruginosa PAO1. Resistance to chromate was not expressed in Escherichia coli. Contiguous 1.6- and 6.3-kilobase HindIII fragments from this plasmid hy...

S INCE THE INITIAL work of Gray and Sterling,”2 the determination of red cell mass with radioactive sodium chromate has undergone several modifications. Read’ developed the technic of adding ascorbic acid in vitro to the blood-sodium chromate mixture to reduce chromate to trivalent chromium and prevent further uptake by red cells. The inhibition of chromium uptake by ascorbic acid supported the...

Using o-pthaldialdehyde (OPT) fluorescence, the amino acids associated with DNA were studied following exposure of intact Chinese hamster ovary cells to chromate. Rigorous extraction with EDTA, acid, or base was required to release the amino acids cross-linked to the DNA isolated from control or chromate-treated cells by standard procedures (i.e., proteinase K, phenol, etc.). Amino acids resist...

Resting cells of Agrobacterium radiobacter EPS-916 grown on glucose, fructose, maltose, lactose, mannitol, or glycerol reduced 0.5 mM chromate. However, resting cells of strain EPS-916 grown on glutamate or succinate did not reduce chromate. The ability of washed cells to reduce chromate was correlated with their redox potential.

Microbial bio-reduction to Cr(III) is a promising strategy for detoxification of chromate, a prevalent anthropogenic pollutant. We propose that this activity can be enhanced in bacteria through engineering of soluble enzymes, such as NfsA, the model Class II chromate reductase of Escherichia coli. We show here that nfsA is induced by chromate, and that it reduces this compound by a “semi-tight”...

Kidney disease is often cited as one of the adverse effects of chromium, yet chronic renal disease due to occupational or environmental exposure to chromium has not yet been reported. Occasional cases of acute tubular necrosis (ATN) following massive absorption of chromate have been described. Chromate-induced ATN has been extensively studied in experimental animals following parenteral adminis...

Chromate [Cr(VI)] is a serious environmental pollutant, which is amenable to bacterial bioremediation. NfsA, the major oxygen-insensitive nitroreductase of Escherichia coli, is a flavoprotein that is able to reduce chromate to less soluble and less toxic Cr(III). We show that this process involves single-electron transfer, giving rise to a flavin semiquinone form of NfsA and Cr(V) as intermedia...

Tandem paired genes encoding putative short-chain monodomain protein members of the chromate ion transporter (CHR) superfamily (ywrB and ywrA) were cloned from genomic DNA of Bacillus subtilis strain 168. The transcription of the paired genes, renamed chr3N and chr3C, respectively, was shown to occur via a bicistronic mRNA generated from a promoter upstream of the chr3N gene. The chr3N and chr3...

OBJECTIVES We aimed to investigate suitable conditions of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and micronucleus (MN) as genotoxic biomarkers at different levels of occupational chromate exposure. DESIGN A cross-sectional study was used. PARTICIPANTS 84 workers who were exposed to chromate for at least 1 year were chosen as the chromate exposed group, while 30 non-exposed individuals were us...