Thiol and Metal Contents in Periphyton Exposed to Elevated Copper and Zinc Concentrations: A Field and Microcosm Study
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- 作者：Sé ; verine Le Faucheur ; Renata Behra ; and Laura Sigg
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：October 15, 2005
- 年：2005
- 卷：39
- 期：20
- 页码：8099 - 8107
- 全文大小：206K
- 年卷期：v.39,no.20(October 15, 2005)
- ISSN：1520-5851
文摘
Phytochelatins are metal-binding polypeptides producedby algae under metal exposure. The aim of this study wasto investigate the effects of metal concentration variationsin natural systems on periphyton at the biochemical level byanalyzing its intracellular thiol content, in particularphytochelatins. To that purpose, two field campaignswere conducted in a stream subject to an increase ofdissolved metal concentrations (particularly Cu and Zn)during rain events, which results in an increase of theiraccumulation in periphyton. At background metalconcentrations, several thiols were detectable in periphyton,namely, glutathione (GSH), 
-glutamylcysteine (GluCys),phytochelatins (PC2), and some unidentified thiols, U1 and U2.Glutathione and GluCys contents were found to varyindependently of the rain, as well as U1 and U2, whereasthe phytochelatin content increased during the rain events.To investigate whether Cu or Zn may be responsible forthis increase, microcosm experiments were carried out withnatural water enriched with Cu, Zn, and Cd separately,and Cu and Zn in combination. In this study, GSH, PC2, andU1 were also detected, but not GluCys. An increase inaccumulated Cu content did not induce any changes in thiolcontent, whereas an increase of the Zn content induceda decrease in GSH content and an increase in phytochelatincontent. Zinc rather than Cu may thus induce a phytochelatincontent increase in periphyton in the field studies.Addition of Cu and Zn in combination also induced anincrease in phytochelatin content. Cadmium was found tobe the most effective inducer, with the production oflarger phytochelatins (PC3-4). This study is the first one toreport changes in thiol content in periphyton in responseto an increase of the metal concentration in naturalfreshwaters.
-glutamylcysteine (GluCys),phytochelatins (PC2), and some unidentified thiols, U1 and U2.Glutathione and GluCys contents were found to varyindependently of the rain, as well as U1 and U2, whereasthe phytochelatin content increased during the rain events.To investigate whether Cu or Zn may be responsible forthis increase, microcosm experiments were carried out withnatural water enriched with Cu, Zn, and Cd separately,and Cu and Zn in combination. In this study, GSH, PC2, andU1 were also detected, but not GluCys. An increase inaccumulated Cu content did not induce any changes in thiolcontent, whereas an increase of the Zn content induceda decrease in GSH content and an increase in phytochelatincontent. Zinc rather than Cu may thus induce a phytochelatincontent increase in periphyton in the field studies.Addition of Cu and Zn in combination also induced anincrease in phytochelatin content. Cadmium was found tobe the most effective inducer, with the production oflarger phytochelatins (PC3-4). This study is the first one toreport changes in thiol content in periphyton in responseto an increase of the metal concentration in naturalfreshwaters.