Team DeNardo

Carol Christel

Education:

BA. Biology 2000, Lewis and Clark College
Ph.D. Biology, 2006, Arizona State University

Current Position:

Instructor, Department of Biology and Human Biology, Carroll College, Waukesha, Wisconsin

Email:

Research Interest:

My current research interests are the endocrinology of feeding and digestion in Gila Monsters, and how this physiological aspect has influenced their natural history.

Dissertation Work:

My research on Gila Monsters, Heloderma suspectum, combines endocrinology and metabolism with ecological life history. More specifically, I am interested in the role of exendin-4 in Gila Monsters. Exendin-4 is a recently identified peptide hormone isolated from the saliva of the Gila Monster. Research on exendin-4 has focused primarily on its glucose-lowering activity in mammals, which is similar to that associated with glucagon-like peptide 1 (GLP-1). Much of this research is directed towards using exendin-4 as an anti-diabetic agent, and currently synthetic exendin-4 is being tested in clinical trials. While these clinically trials have assessed the efficacy to which exendin-4 achieves a targeted physiological goal, the overall activity of exendin-4 remains poorly understood. This deficiency may result in missed potential implications for biomedical use, missed untoward side-effects, or a missed opportunity for a greater understanding of the physiological mechanisms of glucose homeostasis.

To address this lack of information on exendin-4, I am studying this protein hormone in Gila Monsters. Exendin-4 is found only in this species, which raises several questions as to its role and evolution. My dissertation experiments are designed to describe the function of exendin-4 in Gila Monster physiology with these basic questions in mind:

1) Where is exendin-4 acting?
2) What triggers the release of exendin-4?
3) What affect does exendin-4 have on Gila Monster metabolism?
4) Why and how might this protein hormone have evolved?

By using a captive Gila Monster population, I can measure endogenous exendin-4 levels in response to food, exogenous exendin-4, and anti-exendin-4 treatments. Further experimentation will include exploration into the molecular and cellular mechanisms by which exendin-4 exerts its effect on glucose homeostasis as well as exploration into additional effects on other body systems. The results from my research will not only give us an idea of how exendin-4 is acting in its native organism but also provide insight on the evolution of metabolic control mechanisms.

Past Research:

As an undergraduate at Lewis and Clark College, I worked with Dr. Kenneth Clifton investigating the foraging ecology of shorebirds within coastal wetlands.

Publications:

1. Christel, CM, DeNardo, D. 2006. Release of exendin-4 is controlled by mechanical action in Gila Monsters, Heloderma suspectum. Comparative Biochemistry and Physiology, Part A 143: 85–88.

Email: carolyn.christel@asu.edu