Selenate bioaccumulation and toxicity in Chlamydomonas reinhardtii: Influence of ambient sulphate ion concentration.
The aim of the present study was to investigate selenate toxicity in the unicellular green algae Chlamydomonas reinhardtii as a function of sulphate ion concentration and the relationship with intracellular bioaccumulation. The toxicity of selenate was evaluated by measuring the effect of different selenate concentrations on algal growth during a 96h exposure period. A non-linear regression according to the Hill model was used to describe the dose-effect relationship and estimate the effect concentrations (EC) of selenate. EC(50) values of 0.40[0.24-0.52]micromolL(-1) and of 3.10[1.65-4.86]micromolL(-1) of ambient selenate were obtained, at 8 and 80micromolL(-1) of sulphate ions in the medium, respectively. For non-toxic and low-level ambient selenate concentrations, bioaccumulation in presence of 80micromolL(-1) was one tenth that of 8micromolL(-1) of sulphate ions. When expressed as intracellular selenium burden, EC(50) values determined at 8 and 80micromolL(-1) of sulphate ions were not significantly different (126 and 67nmolSe.10(9)cells(-1), respectively). In conclusion, toxicity appeared to be correlated to selenate bioaccumulation which suggests that toxicity must be linked to intracellular selenium accumulation that is directly dependent on ambient sulphate ions that may compete with selenate for transport sites.
Fournier
Elodie
E
Laboratoire de Radioécologie et Ecotoxicologie, Institut de Radioprotection et de Sûreté Nucléaire Bât 186, BP 3, 13115 Saint-Paul-Lez-Durance cedex, France. fournierelo@free.fr <fournierelo@free.fr>
Adam-Guillermin
Christelle
C
Potin-Gautier
Martine
M
Pannier
Florence
F
D016825:Chlamydomonas reinhardtii / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D008278:Magnesium Sulfate / Q000737:chemistry; D064586:Selenic Acid; D018036:Selenium Compounds / Q000493:pharmacokinetics* / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D018036:Selenium Compounds; D014874:Water Pollutants, Chemical; D008278:Magnesium Sulfate; D064586:Selenic Acid