Selenomethionine Biotransformation and Incorporation into Proteins along a Simulated Terrestrial Food Chain
Jason M. Unrine1, Brian P. Jackson2, and William
A. Hopkins3
1Savannah River Ecology Laboratory, The University of Georgia,
Aiken, SC
2Departments of Chemistry and Earth Sciences, Dartmouth College,
Hanover, NH
3Department of Fisheries and Wildlife Sciences, Virginia Polytechnic
Institute and State University,
Blacksburg, VA
Abstract
Selenium
is an essential trace element in vertebrates, but there is a narrow concentration
range between dietary requirement and toxicity threshold. Although a great
deal is known about the biochemistry of Se from a nutritional perspective,
considerably less attention has been focused on the specific biochemistry
of Se as an environmental toxicant. Recent advances in hyphenated analytical
techniques have provided the capability of quantifying specific chemical
forms of Se in biological tissues as well as the distribution of Se among
macromolecules. We applied liquid chromatography coupled to inductively
coupled plasma mass spectrometry to investigate biotransformations of
selenomethionine along a simulated terrestrial food chain consisting of
selenomethionine exposed crickets (Acheta domesticus) fed to western
fence lizards (Sceloporus occidentalis). Evidence was obtained
for selenomethionine biotransformation as well as for sex-specific differences
in the metabolism of Se compounds and their subsequent incorporation into
proteins in the lizard. The results demonstrate the complexities involved
in trophic transfer of Se due to the potential for extensive biotransformation
and the species- and even sex-specific nature of these biotransformations.
SREL Reprint #3034
Unrine, J.
M., B. P. Jackson, and W. A. Hopkins. 2007. Selenomethionine Biotransformation
and Incorporation into Proteins along a Simulated Terrestrial Food Chain.
Environmental Science & Technology 41(10):3601-3606.
