PH03 Perchlorate
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH051) Immune system responses to perchlorate exposure in native amphbians.
Hensley, A1, Guteirrez, M1, Smith, P1, McMurry, S1, 1 TIEHH, Dept. of Environmental Toxicology, Texas Tech University, Lubbock, Texas, USA
ABSTRACT- The immune system of amphibians is of particular interest in the study of perchlorate toxicity. It is known that perchlorate potently inhibits the thyroid by competing with iodide for uptake into the thyroid, thereby hindering the production of thyroid hormones T3 and T4. In amphibians, this inhibition significantly affects metamorphosis, which is largely regulated by thyroid hormones. Tadpoles exposed to perchlorate exhibit inhibited metamorphosis in a dose dependent manner and concentrations above approximately 140 ppb effectively prevent metamorphosis. When amphibians go through metamorphosis their immune system experiences an extensive reorganization, possibly to avoid an autoimmune response to newly forming adult-specific molecules. Several aspects of the tadpole immune system are reduced during metamorphosis and reconstructed as the animal comes out of metamorphosis. These factors come together to implicate perchlorate exposure as an immunoregulatory agent in amphibians. Alterations in immunocompetance in wildlife can have significant effects on health and survivability. We will present results on the effects of environmentally relevant concentrations of perchlorate on a variety of immunological endpoints in native amphibians. The endpoints include immune organ mass and cellularity, natural killer cell activity, and T and B cell proliferation. Previous researchers have investigated the immunotoxicity of perchlorate to African clawed frogs, however, little is known about perchorate effects on immunity in native amphibians.
Key words: amphibian, perchlorate, immunity