Selenium protein identification and profiling by mass spectrometry: A tool to assess progression of cardiomyopathy in a whale model
Colleen E. Bryana, b, Steven J. Christophera, W. Clay Davisa, Lisa E. Kilpatrick c, Wayne E. McFeed, Gregory D. Bossarte.
aAnalytical Chemistry Division, National Institute of Standards and Technology, Hollings Marine Laboratory, Charleston, SC 29412 USA
bMarine Biomedicine and Environmental Science Center, Medical University of South Carolina, Charleston, SC 29412 USA
cChemical and Biochemical Reference Data Division, National Institute of Standards and Technology, Hollings Marine Laboratory, Charleston, SC 29412 USA
dNOAA National Ocean Service, CCEHBR, Charleston, SC 29412 USA
eGeorgia Aquarium, Atlanta, GA 30313 USA
More than half of pygmy sperm whales (Kogia breviceps) that strand exhibit signs of cardiomyopathy (CMP). Many factors may contribute to the development of idiopathic CMP in K. breviceps, including genetics, infectious agents, contaminants, biotoxins, and dietary intake (e.g. selenium, mercury, and pro-oxidants). This study assessed trace elements and associated proteins in K. breviceps at various stages of CMP progression using fresh frozen liver and heart samples collected from individuals that stranded along U.S. Atlantic and Gulf coasts. First, total Se was measured by collision cell inductively coupled plasma mass spectrometry (ICP-MS) and total Hg was measured by pyrolysis atomic absorption (AA) to examine if the Se/Hg detoxification pathway inhibits the bioavailability of Se. Double spike speciated isotope dilution gas chromatography ICP-MS was utilized to measure methyl Hg and inorganic Hg. Selenium species profiles were examined by multi-dimension liquid chromatography ICP-MS detection, and Se protein identification was performed by liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS/MS). Data collected on trace elements and selenium proteins were evaluated in the context of animal life history and other complementary histological information to gain insight into the biochemical pathways contributing to the development of CMP in K. breviceps. Selenium protein patterns for metallothioneins were different between animals with no pathological findings and those with CMP, indicating that Se protein expression is altered with the disease state in K. breviceps. Profiling Se species with SEC/ICP-MS proved to be a useful tool to identify Se protein pattern differences between heart disease stages and may be applied to other species.