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Phytochelatin induction, cadmium accumulation, and algal sensitivity to free cadmium ion in Scenedesmus vacuolatus
Author(s) -
Le Faucheur Séverine,
Behra Renata,
Sigg Laura
Publication year - 2005
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/04-394r.1
Subject(s) - phytochelatin , cadmium , intracellular , glutathione , thiol , scenedesmus , chlorophyta , chemistry , metal toxicity , algae , environmental chemistry , biochemistry , chromatography , biology , botany , enzyme , organic chemistry
Phytochelatins are small, intracellular, metal‐binding polypeptides produced by algae on exposure to increased metal concentration in their environment. The aim of the present study was to examine the relationship between phytochelatin concentration, bioaccumulated metal, and sensitivity of algal growth on cadmium exposure. For that purpose, intracellular cadmium concentration and thiol (glutathione, γ‐glutamylcysteine [γGluCys], and phytochelatins [PC n ]) content were determined in the freshwater green alga Scenedesmus vacuolatus exposed to growth‐inhibitory and noninhibitory concentrations of free Cd 2+ in the range from 10 −14 to 10 −7 M. The algal growth rate was optimal up to a free Cd 2+ concentration of 10 −9 M and then decreased by 40% at higher concentrations. The intracellular cadmium content increased sharply from 0.22 to 746 amol/cell over this free Cd 2+ range. At the lowest Cd 2+ concentration (control), glutathione was the only detectable thiol (127 amol/cell). With increasing Cd 2+ , formation of γGluCys and phytochelatins from PC 2 to PC 6 were observed. The predominant oligomer was PC 3 , with 42 amol/cell at the highest Cd 2+ concentration (10 −7 M). The ratio of the concentration of total thiol groups to intracellular cadmium was important for maintaining optimal growth. In contrast, thiol groups from phytochelatins were never measured in excess to intracellular cadmium content.