Abstract
Selection of cultured cells of the selenium sensitive and non-accumulating Astragalus cicer for tolerance to stepwise increasing concentrations of selenite in the medium lead to a variant able to grow at 75 microM selenite. The Se-tolerant culture synthesized a selenocysteine methyltransferase immunologically related but not identical to that of the accumulating A. bisulcatus species and produced Se-methyl-selenocysteine in vivo. Re-cultivation in selenium-free medium lead to breakdown of tolerance and the disappearance of the methyltransferase from cellular proteins. The results prove that the non-accumulating species A. cicer has the cryptic capacity for synthesis of a selenocysteine methyltransferase and also demonstrate that synthesis of the organoselenium compounds in Se-accumulating plants are contributing to selenium tolerance.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Blotting, Western
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Cell Division / drug effects
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Cells, Cultured
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Cysteine / analogs & derivatives
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Cysteine / metabolism
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Dose-Response Relationship, Drug
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Drug Tolerance
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Electrophoresis, Gel, Two-Dimensional
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Enzyme Induction
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Isoelectric Point
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Methylation / drug effects
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Methyltransferases / biosynthesis
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Organoselenium Compounds / metabolism
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Plant Cells
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Plant Proteins / metabolism
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Plants / drug effects
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Plants / genetics*
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Plants / metabolism*
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Selection, Genetic*
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Selenium / administration & dosage
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Selenium / metabolism*
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Selenium / pharmacology
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Selenium / toxicity
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Selenocysteine / analogs & derivatives
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Sodium Selenite / administration & dosage
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Sodium Selenite / metabolism
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Sodium Selenite / pharmacology*
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Sodium Selenite / toxicity
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Time Factors
Substances
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Organoselenium Compounds
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Plant Proteins
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Selenocysteine
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Methyltransferases
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selenocysteine methyltransferase
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Selenium
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Sodium Selenite
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Cysteine
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selenomethylselenocysteine