PARENT SESSION
PT3 - Adaptation/Acquired Environmental Resistance
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P587) Antioxidant defenses in killifish (Fundulus heteroclitus) exposed to Superfund sediments: short-term and evolutionary responses.
Meyer, Joel*,1, Smith, James1, Di Giulio, Richard1, 1 Duke University, Durham, NC, USA
ABSTRACT- A population of killifish (Fundulus heteroclitus) inhabiting a Superfund site on the Elizabeth River (VA, USA) is tolerant of the acute toxicity of the sediments from the site; previous work suggests that this tolerance is based both on genetic adaptation and physiological acclimation. In this study, larval 1st- and 2nd-generation offspring of Elizabeth River killifish were found to be more resistant to the toxicity of t-butyl hydroperoxide (a model prooxidant) than were King's Creek (reference site) offpsring, indicating a heritable tolerance of exposure to oxidative stress. In a laboratory experiments designed to elucidate the mechanistic basis for this increased tolerance, we exposed Elizabeth River and King's Creek killifish (wild-caught as well as laboratory-raised F1 and F2 offspring) to Elizabeth River and King's Creek sediments, and measured the following antioxidant parameters: total oxyradical scavenging capacity (TOSC); glutathione content (total and oxidized); activities of glutathione reductase (GR), glutathione peroxidase (GPx), glutathione S-transferase (GST), and glutamate cysteine ligase (GLCL); activities and protein levels of copper-zinc superoxide dismutase; and protein levels of manganese superoxide dismutase (MnSOD). Exposure to Elizabeth River sediments led to consistent increases in total glutathione concentrations and MnSOD protein levels, and in some cases increased GR, GPx, GST, and GLCL activities (in all treated groups). In addition, Elizabeth River offspring (larvae) exhibited higher basal TOSC values, glutathione concentrations, and MnSOD protein levels. These data suggests that upregulated antioxidant defenses play a role in both short-term and multigenerational tolerance of the toxicity of these Superfund sediments. Supported by the Superfund Basic Research Programs Grant ES10356 and by the Office of Naval Research Grant N00014-00-1-0315.
Key words: oxidative stress, polycyclic aromatic hydrocarbons, adaptation, Fundulus heteroclitus