Frog tadpoles undergo remarkable remodeling of the body plan in anticipation of the transition from an aquatic to a terrestrial lifestyle. This metamorphosis is caused by thyroid hormones – the same hormones that are important in all vertebrates for normal growth, development, and health. These hormones have very different effects depending upon the tissue type. In tadpoles, the tail disappears, the legs grow, the skin changes, and the liver and brain remodel – all in response to thyroid hormones. This research program focuses on understanding how these differences come about. We hypothesize that there are specific genes that contribute to these differences and we are identifying them and examining the molecular switches that regulate how they work. Understanding this is important because it gives us fundamental information on different tissue responses that can be used to better design therapeutics used as hormone replacements. It also gives us insight into why some tissues are more sensitive to environmental contaminants that act as hormone disruptors. These endocrine disruptors come from a variety of sources such as plants, pharmaceuticals, pesticides, personal care products, and industry. A better understanding and identification of thyroid hormone disruptors will help develop effective means of keeping track of their release into the environment and contribute to creating safer consumer products.

To accomplish these goals, we are using powerful biochemical and bioinformatics techniques to examine gene expression programs and their controlling factors in tadpole tissues. Since thyroid hormone signaling is important in all vertebrates including humans, the knowledge obtained by studying them will give us important clues in understanding the basis of diseases including cancer and metabolic disorders.