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Louis J. Guillette, Jr. Professor Department of Zoology University of Florida |
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Louis J. Guillette, Jr. Professor Department of Zoology University of Florida |
Contaminants as Hormones: Lessons from Alligators
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| Guest Lecture for
Fall 1999 Graduate Seminar: Hormones, Behavior & Endocrine Discrupting Chemicals in the Environment |
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ABSTRACT: Reproductive and endocrine abnormalities have been described in a number of wildlife species living in contaminated environments. We have observed abnormalities in plasma concentrations of sex steroids and thyroid hormones in alligators at birth suggesting organizational (developmental) changes. Experimental studies have confirmed that exposure of developing alligator embryos to various pesticides or metabolites (e.g., p,p'-DDE, p,p'-DDD, trans-Nonachlor, dicofol, atrazine) can alter (1) sex determination, (2) gonadal steroidogenesis, (3) cliterophallus size, and (4) endocrine or reproductive organ morphology. Concentrations as low as 100 ppt applied onto the outside of the egg shell are effective. Finally, mixtures can exhibit additive or subtractive effects depending on the endpoint examined. These studies provide experimental evidence that embryonic exposure to ecologically relevant concentrations of endocrine disrupting contaminants can induce alterations similar to those reported in wild populations Funded by EPA grants CR821437 and U914738-01-0. 
RELATED READING:Crain, D.A., L.J. Guillette Jr., D.B. Pickford, H.F. Percival, and A.R. Woodward. 1998. Sex-steroid and thyroid hormone concentrations in juvenile alligators (Alligator mississippiensis) from contaminated and reference lakes in Florida. Environmental Toxicology and Chemistry 17:446-452. Crain, D. A., L.J. Guillette Jr., A.A. Rooney, and D.B. Pickford. 1997. Alteration in steroidogenesis in alligators (Alligator mississippiensis) exposed naturally and experimentally to environmental contaminants. Environmental Health Perspectives 105:528-533. Guillette, L.J., Jr., D.A. Crain, A.A. Rooney, and D.B. Pickford. 1995. Organization versus activation: The role of endocrine-disrupting contaminants (EDCs) during embryonic development in wildlife. Environmental Health Perspectives 103 (Suppl. 7):157-164. Guillette, L.J., Jr., T.S. Gross, G.R. Masson, J.M. Matter, H.F. Percival, and A.R. Woodward. 1994. Developmental abnormalities of the gonad and abnormal sex hormone concentrations in juvenile alligators from contaminated and control lakes in Florida. Environmental Health Perspectives 102:680-688. Guillette, L.J., Jr., D.B. Pickford, D.A. Crain, A.A. Rooney, and H.F. Percival. 1996. Reduction in penis size and plasma testosterone concentrations in juvenile alligators living in a contaminated environment. General and Comparative Endocrinology 101:32-42. List of Dr. Guillette's Endocrine Disruptors Publications ONLINE RESOURCES: Dr. Guillette's Departmental Page Dr. Guillette's Research Pages |
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| OTHER FALL 1999 SPEAKERS: Theo Colborn . David Crews . Victor Apanius . Fred vom Saal |
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