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Mercury and selenium speciation and toxicity in common loonsFarren, Alex January 2004 (has links)
Approximately 10,000 tones of Hg are deposited annually as a result of anthropogenic activities. This increased Hg burden is known to have adverse neurological and reproductive effects on Common loons. A positive correlation between mercury (Hg) and selenium (Se) has been reported to exist in marine mammals and various species of marine and aquatic piscivorous birds. It has been hypothesized that the Hg/Se interactions may involve in the multiple mechanisms of Hg detoxification. This study focused on the suggested Hg/Se complex that forms in association with specific proteins. Specifically, this project focuses on the nature of these interactions in different tissues from wild Common loons (Gavia immer) that have been collected by the Canadian Wildlife Service. The Hg and Se concentrations in the various tissues were quantified using AAS. MALDI-TOF-MS and protein sequencing characterized the nature of the Hg/Se complex binding protein. Among the tissues, the liver had the highest concentrations of Hg and Se followed by kidney; muscle and brain. A strong association between Hg and Se was found in liver, kidney and eggs whereas there was no association in muscle and brain. In contrast brain and muscle had highest percentage of organic Hg suggesting that only inorganic Hg is associated with Se. Two Hg-Se binding protein complexes were found in liver both in the 15,200-15,300 Da range while one such complex in the same weight range was found in kidneys, when sequenced it was found that these proteins were the alpha A chain of Hemoglobin. The protein complex found in eggs was unique and although it was impossible to fully sequence it, it represents an unknown protein. The role of Se in Hg toxicity in eggs warrants further study.
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Characterization of mercury and selenium complex in ringed seal liverHa, Pengcheng, 1963- January 2001 (has links)
Ringed seal (Phoca hispida) is a major component and a major source of mercury (Hg) in the Inuit traditional diet. A high correlation between Hg and selenium (Se), as different forms of Hg-Se complex, has been reported in many species of marine mammals. The chemical form of the Hg-Se complex in ringed seals has never be characterised. In this study, Hg and Se concentrations in different seal tissues: liver, kidney, muscle and brain, were measured. The highest Hg and Se concentrations were found in the liver and a strong linear correlation was also observed between Hg and Se concentration in the seal liver. Extensive chromatographic and mass spectrometry techniques have been used to isolate and characterize the Hg and Se ligands in seal liver. Extraction of Hg and Se showed that Hg and Se were bound to ligands within the cell membranes of ringed seal liver. The Hg/Se binding protein has a MW range of about 65 kDa and Hg and Se had a 1:1 molecular ratio. The Hg/Se binding protein may contain 3 major polypeptides with MW of 6510.8, 14305.1 and 14353.1 Da. The toxicology of this Hg/Se binding protein will be studied using an animal feeding experiment.
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Mercury and selenium speciation and toxicity in common loonsFarren, Alex January 2004 (has links)
No description available.
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Characterization of mercury and selenium complex in ringed seal liverHa, Pengcheng, 1963- January 2001 (has links)
No description available.
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Selenium and trace metal accumulation in detrital-benthic food webs of lotic and lentic wetlands, Utah, USAHillwalker, Wendy E. 24 May 2004 (has links)
Concentrations of selenium (Se), manganese (Mn), zinc (Zn), cadmium (Cd), lead
(Pb) and arsenic (As) were measured in the water column, sediment and biota, in conjunction
with selected physicochemical data, from representative wetland types at a mining site within
Salt Lake County, Utah, USA. The selected field sites included Oolitic Pond (lentic) and Lee
Creek (lotic), which are moderately contaminated brackish, alkaline aquatic wetlands
managed by a copper mining industry. These fishless wetlands are located in a geographic
region that poses risk to migratory shorebird populations from dietary Se. A spatial sampling
study demonstrated the extent of variation in total Se concentration within the wetlands. With
the exception of the sediment compartment, Se concentration did not differ significantly along
the 2-mile length of Lee Creek or within the Pond. The differences in sediment total Se
concentrations between the Creek East and West segments characterize lower Lee Creek as
having two segments distinguished by unique processes that influence the sediment Se
accumulation profiles. Se accumulation trends were observed temporally over 3-years (2000
to 2002) and over two seasons (spring and autumn). Total Se body burden in benthic
invertebrates was more clearly associated with sediment/detritus Se concentrations than with
surface water concentrations. Three invertebrate groups dominated the aquatic invertebrates
assemblage in the lotic and lentic benthos; primary consumers (Chironomidae, Diptera),
generalist feeders (Hemiptera) and predators (Odonata). The chironomid larvae accumulated
1.3 to 39 times the trace metal concentrations of the Hemiptera or odonate taxa, independent
of trace metal type (essential or non-essential) or wetland occupation. Organism-specific
factors, such as habitat selection and preferential feeding habits, were proposed to influence
benthic invertebrate accumulation profiles by modifying trace metal exposure. Mixed diets,
trophic omnivory and the complexity of wetland biogeochemistry limit the power of stable
nitrogen fractionation signatures to define benthic food web relationships. Wetland site-specific
processes impacted Se accumulating efficiency, with trace metal concentrations from
4 to 7 times greater within the lentic benthic system than the lotic. The fractionation of the
natural abundant stable carbon isotopes revealed the importance of sedimentary and detrital
organic carbon as dietary sources for the benthic food web. Sediment organic content was not
significantly associated with sediment, or invertebrate, Se accumulation profiles. Ecological
risk assessments based on sound understanding of metal chemistry and the interactions
between the sediment matrix and benthic organisms are necessary to provide tools for
environmental management. / Graduation date: 2005
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