title: Exposure-dose-response of Tellina deltoidalis to contaminated estuarine sediments 3. Selenium spiked sediments.
abstract: The metalloid selenium is an essential element which at slightly elevated concentrations is toxic and mutagenic. In Australia the burning of coal for power generation releases selenium into estuarine environments where it accumulates in sediments. The relationship between selenium exposure, dose and response was investigated in the deposit feeding, benthic, marine bivalve Tellina deltoidalis. Bivalves were exposed in microcosms for 28 days to individual selenium spiked sediments, 0, 5 and 20 μg/g dry mass. T. deltoidalis accumulated selenium from spiked sediment but not in proportion to the sediment selenium concentrations. The majority of recovered subcellular selenium was associated with the nuclei and cellular debris fraction, probably as protein bound selenium associated with plasma and selenium bound directly to cell walls. Selenium exposed organisms had increased biologically detoxified selenium burdens which were associated with both granule and metallothionein like protein fractions, indicating selenium detoxification. Half of the biologically active selenium was associated with the mitochondrial fraction with up to 4 fold increases in selenium in exposed organisms. Selenium exposed T. deltoidalis had significantly reduced GSH:GSSG ratios indicating a build-up of oxidised glutathione. Total antioxidant capacity of selenium exposed T. deltoidalis was significantly reduced which corresponded with increased lipid peroxidation, lysosomal destabilisation and micronuclei frequency. Clear exposure-dose-response relationships have been demonstrated for T. deltoidalis exposed to selenium spiked sediments, supporting its suitability for use in selenium toxicity tests using sub-lethal endpoints.
authors.affiliation: Ecochemistry Laboratory, Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia. Electronic address: anne.taylor@canberra.edu.au.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Taylor
authors.affiliation: Ecochemistry Laboratory, Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.
authors.forename: William A
authors.initials: WA
authors.lastname: Maher
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D049872:Bivalvia / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000009:adverse effects*; D004787:Environmental Pollution; D063366:Estuaries; D005978:Glutathione / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008247:Lysosomes / Q000187:drug effects; D048629:Micronuclei, Chromosome-Defective / Q000139:chemically induced / Q000662:veterinary; D008928:Mitochondria / Q000737:chemistry / Q000187:drug effects; D009153:Mutagens / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D009517:New South Wales; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D012643:Selenium / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D014018:Tissue Distribution
chemical_list: D015415:Biomarkers; D009153:Mutagens; D012987:Soil; D012989:Soil Pollutants; D005978:Glutathione; D012643:Selenium
keywords: Biomarkers; Bivalve; Lipid peroxidation; Lysosomes; Micronuclei; Oxidative stress; Subcellular selenium