Metabolism of selenomethionine by rainbow trout (Oncorhynchus mykiss) embryos can generate oxidative stress

Vince P. Palace, Julian E. Spallholz, Jodi Holm, Kerry Wautier, Robert E. Evans, Christopher L. Baron

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


Although selenium is required by vertebrates, toxicity can arise at concentrations only slightly greater than those they require. The toxicity of Se is thought to arise from its ability to substitute for sulfur during the assembly of proteins. However, recent studies also indicate that some forms of selenium are capable of generating oxidative stress in an in vitro test system that includes glutathione. L-Selenomethionine, the predominant form of selenium in the eggs of oviparous vertebrates, does not generate oxidative radicals in this system, but lesions consistent with oxidative stress have been identified in fish and birds with high concentrations of Se. Here we report on the ability of rainbow trout embryos to transform L-Selenomethionine to a form capable of producing a superoxide radical. Oxidative stress appears to be generated by methioninase enzyme activity in the embryos that liberates methylselenol from L-Selenomethionine. Methylselenol redox cycles in the presence of glutathione producing superoxide and likely accounts for oxidative lesions present in fish and birds environmentally exposed to excessive loads of selenomethionine.

Original languageEnglish
Pages (from-to)17-21
Number of pages5
JournalEcotoxicology and Environmental Safety
Issue number1
StatePublished - May 2004


  • Biotransformation
  • Oxidative stress
  • Rainbow trout
  • Selenium
  • Superoxide radical
  • Teratogensis


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