Document Detail

Phytochelatin induction by selenate in Chlorella vulgaris, and regulation of effect by sulfate levels.
MedLine Citation:
PMID:  21038439     Owner:  NLM     Status:  In-Process    
Phytochelatins (PCs) are short metal detoxification peptides made from the sulfur-rich molecule glutathione. The production of PCs by algae caused by Se exposure has never been studied, although many algae accumulate Se, forming Se-rich proteins and peptides, and higher plants have demonstrated PC production when treated with Se; therefore, a goal of the current study was to examine whether Se induces PC production in algae. Furthermore, selenate is thought to compete with sulfate in the S assimilation pathway, and sulfate therefore may have a protective effect against the toxic effects of high doses of Se in algae. Hence, the interaction of selenate and sulfate was investigated with respect to the induction of PCs. Chlorella vulgaris was cultured in media with either low (31.2 µM) or high (312 µM) concentrations of sulfate. These cultures were exposed to selenate in doses of 7, 35, and 70 nM for 48 h. In a separate treatment, Cd (890 nM) was added as a positive PC-inducing control, and one no-metal negative control was used. Total Se and Se speciation were determined, and glutathione, phytochelatin-2, and phytochelatin-3 were quantified in each of cell digests, cell medium, and cell lysates. We found that PCs and their precursor glutathione were induced by selenate as well as by a Cd control. The high concentration of sulfate was able to counter selenate-induced production of PCs and glutathione. These data support two possible mechanisms: a negative feedback system in the S assimilation pathway that affects PC production when sulfate is abundant, and competition for uptake at the ion transport level between selenate and sulfate.
Denina B D Simmons; R J Neil Emery
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental toxicology and chemistry / SETAC     Volume:  30     ISSN:  1552-8618     ISO Abbreviation:  Environ. Toxicol. Chem.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-01-13     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8308958     Medline TA:  Environ Toxicol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  469-76     Citation Subset:  IM    
Copyright Information:
© 2010 SETAC.
Environmental & Life Sciences, Trent University, Peterborough, Ontario, Canada.
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