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Dissolved organic carbon reduces uranium toxicity to the unicellular eukaryote Euglena gracilis.
MedLine Citation:
PMID:  22278366     Owner:  NLM     Status:  Publisher    
The influence of dissolved organic carbon (DOC), in the form of Suwannee River fulvic acid (SRFA), on uranium (U) toxicity to the unicellular eukaryote, Euglena gracilis (Z strain), was investigated at pH 6. In a background medium without SRFA, exposure of E. gracilis to 57 μg L(-1) U resulted in a 50% reduction in growth (IC(50)). The addition of 20 mg L(-1) DOC (as SRFA), reduced U toxicity 4 to 5-fold (IC(50) increased to 254 μg L(-1) U). This reduction in toxicity was also evident at more sensitive effect levels with a 10% reduction in growth (IC(10)) occurring at 5 μg L(-1) U in the background medium and at 17 μg L(-1) U in the SRFA medium, respectively. This amelioration of toxicity with the addition of SRFA was linked to a decrease in the bioavailability of U, with geochemical speciation modelling predicting 84% of U would be complexed by SRFA. The decrease in bioavailability of U in the presence of SRFA was also evident from the 11-14 fold reduction in the cellular concentration of U compared to that of E. gracilis in the background medium. Stepwise multiple linear regression analyses indicated that UO(2) (2+) alone explained 51% of the variation in measured U toxicity to E. gracilis. Preliminary U exposures to E. gracilis in the presence of a reactive oxygen species probe, suggest exposure to ≥60 μg L(-1) U may induce oxidative stress, but this endpoint was not considered to be a sensitive biological indicator.
Melanie A Trenfield; Jack C Ng; Barry Noller; Scott J Markich; Rick A van Dam
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-26
Journal Detail:
Title:  Ecotoxicology (London, England)     Volume:  -     ISSN:  1573-3017     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-26     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9885956     Medline TA:  Ecotoxicology     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Ecotoxicology Program, Environmental Research Institute of the Supervising Scientist, GPO Box 461, Darwin, NT, 0801, Australia,
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