The present study aimed to investigate the effects of root surface iron plaque on the uptake kinetics of arsenite and arsenate by excised roots of rice (Oryza sativa) seedlings. The results demonstrated that the presence of iron plaque enhanced arsenite and decreased arsenate uptake. Arsenite and arsenate uptake kinetics were adequately fitted by the Michaelis-Menten function in the absence of ...

Two types of arsenate-resistant mutants of Micrococcus lysodeikticus were found: (i) mutants that grow in the presence of 10 mM but not 1 mM phosphate (Pi) with low uptake rate for Pi and arsenate, and (ii) mutants able to grow in the presence of 10 mM and 1 mM Pi, with a near-normal uptake rate for Pi but a low one for arsenate. The Km values for Pi transport and the Ki values for its competit...

It has been proposed that the absence of photosynthesis in Chlamydomonas reinhardii produces a relative arsenate resistance and that selection for arsenate resistance therefore serves as an enrichment for nonphotosynthetic mutants (Togasaki and Hudock 1972; Harris, Boynton and Gillham 1974). We have found that: 1. mutants selected for arsenate resistance are not substantially enriched for aceta...

BACKGROUND Assessment of soil arsenic (As) bioavailability may profoundly affect the extent of remediation required at contaminated sites by improving human exposure estimates. Because small adjustments in soil As bioavailability estimates can significantly alter risk assessments and remediation goals, convenient, rapid, reliable, and inexpensive tools are needed to determine soil As bioavailab...

Arsenate is an abundant oxyanion that, because of its ability to mimic the phosphate group, is toxic to cells. Arsenate reductase (EC; encoded by the arsC gene in bacteria) participates to achieve arsenate resistance in both prokaryotes and yeast by reducing arsenate to arsenite; the arsenite is then exported by a specific transporter. The crystal structure of Bacillus subtilis arsenate reducta...

Arsenic is an important environmental toxicant which is usually found in drinking water in inorganic form. The hypothesis tested in this investigation is; arsenic exposure causes neural tube defects (NTDs) andthese defects of the central nervous system are more likely related to folate deficiency during fetal life. In this study, sodium arsenate was administered via intraperitoneal route at a r...

The arsenic (As) solid-state speciation (i.e., oxidation state, precipitates, and adsorption complexes) is one of the most important factors controlling dissolved As concentrations at As contaminated sites. In this case study, two representative subsurface samples (i.e., oxidized and semi-reduced sites) from former lead arsenate contaminated soils in the northeastern United States were chosen t...

The recent claim by Wolfe-Simon et al. that the Halomonas bacterial strain GFAJ-1 when grown in arsenate-containing medium with limiting phosphate is able to substitute phosphate with arsenate in biomolecules including nucleic acids and in particular DNA(1) arose much skepticism, primarily due to the very limited chemical stability of arsenate esters (see ref. 2 and references therein). A major...