Mercury (Hg) is a toxicant of global concern, but few strategies exist to evaluate its biological effects on the ecosystem. Piscivorous wildlife, such as mink (Mustela vison), are particularly at risk because they can bioaccumulate Hg to concentrations known to impair neurological systems. Given that biochemical changes in the brain precede functional and structural impairments, I evaluated the use of neurochemicals as early-warning biomarkers of Hg toxicity in mink. Initial studies demonstrated that neurochemical biomarkers could be measured from mink carcasses collected from the field, as long as factors such as storage temperature and freeze thaw cycles were accounted for. To determine if Hg could directly impair neurochemicals in mink, an in vitro study demonstrated that Hg (HgCl2 and MeHg) could inhibit radioligand binding to the muscarinic cholinergic (mACh) receptor in the cerebellum and cerebral cortex regions of the brain. By analyzing whole brains collected from wild mink, it was demonstrated that a significant positive correlation existed between concentrations of brain Hg and levels of mACh receptors. These field observations were confirmed by results from a controlled methyl Hg (MeHg) feeding trial in captive mink, whereby sub-chronic exposure of mink to 0.5 - 2 ppm MeHg (ecologically relevant levels) resulted in significant increases in acetylcholinesterase activity and mACh receptor levels in specific brain regions. Collectively, these results demonstrated that exposure of mink to environmentally realistic concentrations of Hg can be related to alterations in neurochemicals at multiple tiers of biological organization. Given the importance of a functional nervous system in wildlife health, the physiological and ecological significance of these findings need further exploration. The results demonstrate that neurochemical approaches may be novel biomarkers to assess the ecotoxicology of Hg, and by extension, other pollutants o
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85882 |
| Date | January 2005 |
| Creators | Basu, Niladri |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Natural Resource Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002269054, proquestno: AAINR21619, Theses scanned by UMI/ProQuest. |
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