Article

Archives of Environmental Contamination and Toxicology

, Volume 27, Issue 4, pp 449-453

First online:

Effects of sulfate on selenate uptake and toxicity in the green alga Selenastrum capricornutum

  • M. J. WilliamsAffiliated withDepartment of Land, Air, and Water Resources, University of California
  • , R. S. OgleAffiliated withDepartment of Land, Air, and Water Resources, University of California
  • , A. W. KnightAffiliated withDepartment of Land, Air, and Water Resources, University of California
  • , R. G. BurauAffiliated withDepartment of Land, Air, and Water Resources, University of California

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Abstract

Sulfate and selenate compete for active transport across cell membranes via a common permease, suggesting that a significant interaction may exist between uptake of the two ions. The effect of sulfate on selenate uptake and toxicity in Selenastrum capricornutum was investigated using two sulfate levels (3.3 and 33 mg/L S, as SO4) and two selenate levels (10 and 100 μg/L Se, as SeO4). This provided four treatments: one with S:Se molar ratio of 75, two with molar ratios of 750, and one with a molar ratio of 7,500. Selenium uptake and toxicity analyses demonstrated antagonism between the two anions. Increasing sulfate resulted in significantly reduced selenate uptake and increased algal growth. There was a significant difference in selenate uptake between the two treatments with the same S:Se molar ratio suggesting different relative permease affinities for each of the ions at different substrate levels (i.e., above and below permease saturation levels) and/or the presence of two different permease systems. The environmental significance of sulfate and selenate antagonism is discussed.