| dc.description.abstract | A growing body of evidence suggests that endocrine disrupting compounds present in the environment have the ability to impair thyroid function, which may consequently interfere with essential processes such as growth and development. Therefore, it is important to test new and existing chemicals for their ability to disrupt thyroid function. Testing the effects of these compounds on aquatic organisms is necessary due to the pervasive nature of thyroid disrupting chemicals in the aquatic environment. The fathead minnow (Pimephales promelas) is frequently used to study acute toxicity, but recently studies have used this species to screen chemicals for endocrine disrupting capabilities. If fathead minnows are to be used in this capacity, we must first determine how known thyroid disruptors affect this species. As such, the goal this study is to expose developing fathead minnows to a low, medium, or high dose of propylthiouracil (PTU; a known thyroid inhibitor) for 35 days, and determine the effects of this compound on a variety of endpoints. Specifically, we measured markers of growth, morphology, and thyroid related gene expression. Fish exposed to the highest dose of PTU experienced significant reductions in mass, length, as well as skin pigmentation compared to the control. Additionally, the high dose PTU exposed fish exhibited significant alterations in the expression of four of ten thyroid related genes evaluated (tr-beta, ttr, di2, di3). The results of this study suggest that metrics of growth, pigmentation, and gene expression are able to indicate thyroid disruption in the developing fathead minnow. | |
