PARENT SESSION
MA2 - Aquatic Toxicology
Chair: Spehar, Bob1, 1 U.S. EPA, Duluth, MN
Co-chair: Henry, Mary2, 2 U.S. Fish and Wildlife Service, Arlington, VA
8:00 AM to 12:00 PM - Monday, 18 November 2002
Room Ballroom J
(176) The Effects of Perchlorate on Reporduction of Female Xenopus.
Dumont, James*,1, Burkhart, James2, Nzengung, Valentine3, Collier, Joshua1, 1 Oklahoma State University, Stillwater, OK2 NIEHS, Research Triangle Park, NC3 University of Georgia, Athens, GA
ABSTRACT- Ammonium prechlorate is a pervasive pollutant whose source in the environment is primarily from rocket fuel and some fertilizers. Perchlorate is known to affect thyroid function by competing with iodine binding sites in the thyroid gland. Although much is known about the effects of perchlorate on amphibian laraval growth and metamorphosis, little is known about its effects on the reproductive capacity of adults. We exposed four groups of adult female Xenopus to four different concentrations of perchlorate - 10, 100, 1000 and 2000 mg/L- for four months. Prior to exposure, females were induced to ovulate and were mated to marked males. Fecundity, fertilization rates, and hatching success of the embryos were recorded. After exposure, the females were again mated to the same males. Fecundity, fertilization rates, and hatching success were recorded again. Perchlorate exposure reduced all three parameters. Embryos derived from the post-treatment breedings showed a significantly reduced growth (length) after 96 hr. compared to controls. Further they showed an increased number of developmental abnormalities. The presence of thyroxin in amphibian oocytes and early embryos has been reported. The results of the present studies suggest that in addition to reduction in reproductive capacity, there may be trans-generational effects that influence growth and normal development of the early embryos. None of the adults showrd significant changes in body weight over the exposure period. Analysis of organ weights indicates a slight increase in liver weight in those females treated with 2000 mg/L perchlorate. Analyses of blood thyroxin levels and body/organ burdens of perchlorate are in progress and will be reported. (Research supported by the Strategic Environmental Research and Development Program, SERDP)
Key words: perchlorate, Xenopus, reproduction, fecundity