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The Effects of Endocrine Disruptors on the Sexual Differentiation of the Brain and Gonads of Larval Oak Toads (Bufo quercicus) from the Florida EvergladesEPA Grant Number: U916214
Title: The Effects of Endocrine Disruptors on the Sexual Differentiation of the Brain and Gonads of Larval Oak Toads (Bufo quercicus) from the Florida Everglades
Investigators: Ganser, Lisa R.
Institution: University of Miami
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $96,172
RFA: Minority Academic Institutions (MAI) Fellowships for Graduate Environmental Study (2003) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Natural and Life Sciences , Biology/Life Sciences
The objective of this research project is to study the effects of endocrine disruptors on the sexual differentiation of the brain and gonads of larval Oak Toads, Bufo quercicus, from the Florida Everglades. The endocrine system serves as one of the main control systems of the body. During the larval period, hormones help to organize bipotential reproductive tissues in the brain and the gonads into their male or female forms. It is during this critical period of organization that manmade chemicals or endocrine disruptors in the environment, may disrupt the normal cascade of hormonal events that govern the function and form of reproductive tissues. These endocrine disruptors, often found in pesticides and industrial wastes, have been known to affect the morphology of the gonads as well as the mating behaviors of exposed animals.
I will collect Oak Toads, B. quercicus, from various sites in South Florida. I will breed the toads and sample animals at various stages of the larval period. Histological sections will be made of the gonads and the brain at various larval stages. The timing of sexual differentiation of the gonads will be determined by the stage of the larval period at which the gonad appears to be a fully formed ovary or testis. Immunohistochemistry methods will be used to determine any sexual differences in brain morphology by assessing any variations in arginine vasotocin (AVT) receptor populations in the areas of the brain responsible for mate calling. After the timing of sexual differentiation of the gonads and any sexual differences in brain structure are determined, new Oak Toad specimens will be treated with the endocrine disrupting pesticide, atrazine. Using the histological methods mentioned above, I will assess any affects of atrazine on the sexual differentiation of the brain and gonads of the Oak Toad.