Affiliations: Research Center for Eeo-Environmental Sciences,
Chinese Academy of Sciences, Beijing 100085, China | Shanghai Academy of Environmental Sciences, Shanghai
200233, China
Abstract: In the present study, arsenate (As(V)) and phosphate
(P(V)) interactions were investigated in growth, uptake and RNA content in
yeast (Saccharomyces cerevisiae). Yeast grew slowly with As(V) concentrations
increasing in the medium. However, the maximal population density was almost
the same among different As(V) treatments. It was in the late log phase that
yeast growth was augmented by low As(V), which was maybe due to the fact that
methionine metabolism was stressed by vitamin B_6
deprivation, so As(V) treatments did not affect maximal population density.
However, with P(V) concentrations increasing, the maximal population density
increased. Therefore, the maximal population density was determined by P(V)
concentrations in the medium but not by As(V) concentrations in the medium.
Ycf1p (a tonoplast transpor) transports As(GS)_3 into the
vacuole, but arsenic (As) remaining in the thalli was 1.27% with As(V) exposure
for 60 h, from which it can be speculated that the percentage of As transported
into vacuole should be lower than 1.27%. However, the percentage of As pumped
out of cell was 71.49% with As(V) exposure for 68 h. Although two pathways
(extrusion and sequestration) were involved in As detoxification in yeast, the
extrusion pathway played a major role in As detoxification. RNA content was the
highest in the early-log phase and was reduced by As(V).
Keywords: yeast, maximal population density, arsenic essentiality, arsenic speciation
