HP4 Environmental Metabolomics
204 Oregon Ballroom
1:20 PM - 5:20 PM, Thursday
() Metabolomic-proteomic studies of selenium-exposed aquatic embryos by multi-dimensional NMR, tandem-MS, and confocal microscopy.
Fan, T1, Vines, C2, Fairbairn, E.2, Cherr, G2, Higashi, R3, 1 Dept. of Chemistry, Univ. of Louisville, Louisville, KY, USA2 Bodega Marine Laboratory, Univ. of California-Davis, Bodega Bay, CA, USA3 Center for Health and Environment, Univ. of California-Davis, Davis, CA, USA
ABSTRACT- Merging our two decades of in vivo and in vitro metabolite profiling in aquatic organisms with ten years of work in biochemical ecotoxicology of selenium (Se), our recent studies into aquatic embryos aim at toxicity mechanisms. Se is a naturally-occuring, anthropogenically-redistributed trace element with an extremely narrow range between nutrient sufficiency and toxicity. Paradoxically, while nutritional Se is important to anti-oxidant activity, one of the mechanisms of toxicity is oxidative damage through CH3Se- or other species; the mechanism(s) depend on chemical form of Se. Although the main exposure to Se is considered to be dietary for terrestrial and aquatic adult organisms, for aquatic embryos Se doses may be a combination of maternal transfer and water-column exposure. Due to the biochemical complexity of Se effects, both proteomic and metabolomic tools are used; the latter combines NMR and MS, with selected endpoints monitored by confocal fluorescence microscopy. In sea-urchin and zebrafish models, embryos were exposed to selenite, selenate, selenomethionine, and methylselenenic acid, which are in order of increasing toxicity. The metabolic responses of these models are being compared to parallel human lung cancer cell studies, in which we found selenite-induced accumulation of Orn and Arg, possibly linking to cytoplasmic ornithine decarboxylase (ODC) redistribution. This implicates the involvement of protein kinase C (PKC); selenite is known to inactivate PKC catalytic sites. The change in ODC pattern is expected to be related to the accumulation of polyamines. These and other pathway responses are used as testbed hypotheses regarding toxic mechanisms in aquatic embryos. In addition, to aid interpretation of the compartmentation of metabolic dynamics, various fluorescence probes (e.g. reactive oxygen) and endogenous fluorphores (e.g. NADPH) are measured in developing embryos by confocal microscopy. Current plans call for experiments with specific knockouts to block ODC and other pathway nodes.
Key words: selenium, metabolomics, zebrafish, sea urchin