To investigate the effects of methylmercury (MeHg) on development, Xenopus tropicalis tadpoles were exposed to MeHg diets with concentrations of 0.42 (control), 44 (low), and 270 (high) ng/g wet weight. Increased mortality, decreased metamorphosis, increased size, and a greater number of days between tadpoles reaching metamorphosis were observed in the high MeHg group, suggesting disruption to the thyroid axis. Triiodothyronine levels, however, were not significantly different between groups. In both the control and low MeHg groups, total Hg and MeHg body burdens increased rapidly, reached a plateau and eventually declined with a lower percent MeHg body burden. In the high MeHg group, body burden concentrations increased throughout the experiment. This study demonstrates that at low dosages of MeHg, elimination may prevent toxic exposure whereas at high dosages, demethylation and selective excretion mechanisms may be overwhelmed and disruption of development or death may occur in tadpoles.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/27676 |
| Date | January 2008 |
| Creators | Davidson, Melissa Anne |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 124 p. |
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