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dc.contributor.advisorJeffries, Marlo K.
dc.contributor.authorYost, Ally
dc.date2015-05-01
dc.date.accessioned2016-02-19T15:38:55Z
dc.date.available2016-02-19T15:38:55Z
dc.date.issued2015
dc.identifier.urihttps://repository.tcu.edu/handle/116099117/10464
dc.description.abstractOver the past 30 years amphibian populations have been declining globally. Exposure to environmental contaminants could be contributing to this global decline. Polybrominated diphenyl ether 47 (PBDE-47, a flame retardant) is a ubiquitous aquatic contaminant that leaches out of plastics, furniture, vehicles, and electronics into the air, soil, and water. Studies have shown that this organobromide compound may have thyroid-disrupting activity that alters the growth and development of exposed organisms. In this study, African clawed frog (Xenopus laevis) tadpoles were exposed to three environmentally-relevant concentrations of PBDEs via their diets for 21 days beginning at developmental stage 52. Tadpole mass, hind-limb length and developmental stage were evaluated on days 0, 7, 14 and 21, and expression of thyroid-related genes were measured at the conclusion of the exposure. Xenopus tadpoles exposed to the highest PBDE concentration were significantly smaller and less developed than controls. The expression of beta transcription element-binding protein (BTEB), thyroid-stimulating hormone beta (TSH-beta), deiodinase 1 (DI1), deiodinase 2 (DI2), thyroid receptor alpha (TR-alpha), and thyroid receptor beta (TR-beta) were all significantly decreased in the medium and high dose groups compared to the control. These results indicate that PBDE-47 is a thyroid-disruptor that inhibits metamorphosis and growth through alterations in thyroid-related gene expression. Future studies aimed at uncovering the mechanism by which PBDE-47 alters thyroid-related gene expression are warranted to decipher their effects in amphibians.
dc.subjectPBDE-47
dc.subjectamphibians
dc.subjectthyroid system
dc.subjectthyroid disruptor
dc.subjectXenpus laevis
dc.titleGlobal Amphibian Declines: Are Exposures To Polybrominated Diphenyl Ethers A Contributing Factor?
etd.degree.departmentBiology
local.collegeCollege of Science and Engineering
local.collegeJohn V. Roach Honors College
local.departmentBiology


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