F. Boisson et al., TOXICITY AND ACCUMULATION OF SELENITE AND SELENATE IN THE UNICELLULARMARINE ALGA CRICOSPHAERA-ELONGATA, Archives of environmental contamination and toxicology, 28(4), 1995, pp. 487-493
The toxicity and bioaccumulation of selenium in the 4(+) and 6(+) oxid
ation states were investigated in a marine unicellular alga Cricosphae
ra elongata in culture. Selenite was more toxic than selenate. Exponen
tially growing cells and cells in the stationary phase of C, elongata
rapidly accumulated selenite (0.1 and 1.0 mg/L Na2SeO3) and selenate (
0.1 and 1.0 mg/L Na2SeO4). Within the first two hours of contact, the
amount of selenium taken up decreased sharply in exponentially growing
cells, while cells in the stationary phase continued accumulating sel
enium until a plateau was reached. The presence of metabolic inhibitor
s such as KCN (potassium cyanide) or DCMU (3-(3,4-dichloro-phenyl)-1,1
dimethylurea) or glutaraldehyde did not modify the first phase of acc
umulation of selenite by C. elongata in the stationary phase, whereas
further accumulation was inhibited. Possible mechanims of accumulation
of selenium are discussed. In a series of long term experiments (14 o
r 31 d), intracellular partitioning of Se in C. elongata cells, expose
d to selenite, was analysed; total, protein-bound and free cytosolic s
elenium concentrations increased with selenium concentration added to
the culture medium (O.1 or 1 mg/L Na2SeO3) and with exposure time (at
0.1 mg/L Na2SeO3) from 14 d or 31 d. Most of the selenium was associat
ed with proteins; these proteins may represent a form of storage or de
toxication of selenium.