This project, a collaborative effort between a physiological ecologist and a cell physiologist, is a continuation of an investigation into physiological mechanisms contributing to extreme tolerance of cold in northern amphibians and reptiles. The thesis of this proposal is that urea, an important osmolyte in amphibians, may have important, previously undocumented functions in hibernation physiology and cold hardiness. This investigation focuses on the wood frog (Rana sylvatica), the most extensively studied of all freeze-tolerant vertebrates. One set of studies will confirm and extend a preliminary finding that wood frogs accumulate and retain urea during hibernation. The work will determine whether these frogs facilitate urea accumulation by accelerating ureogenesis, and whether their tissues contain certain osmolytes (methylamines) known to function as urea counteractants. Other studies will test the hypothesis that urea accumulated during terrestrial hibernation contributes to freezing survival, perhaps bolstering current views on the evolutionary significance of overlapping adaptations for cryoprotection and dehydration tolerance. Finally, the work will determine whether urea accumulation contributes to metabolic depression in hibernating wood frogs, as has been postulated for estivating organisms. The metabolic effects of urea will be examined at the whole-animal level, in isolated organs, and in the activity of the erythrocyte Na+-K+ pump. The project will foster a nascent research collaboration between investigators at Miami University, an institution that excels in undergraduate education and select graduate programs, and Eastern Illinois University, an RUI institution with a distinguished record of undergraduate research and scholarship. The investigators' strongly overlapping research and educational interests, as well as their complementary backgrounds and expertise, will enhance the research productivity of all persons involved in the project. Further, the project will contribute to the professional development of students at Miami University and Eastern Illinois University by engaging them in all phases of the research process, and by encouraging student researchers to seek funding from internal and external sources; to publish their work in peer-reviewed journals; and to communicate their findings at regional and national meetings. The investigators will promote greater diversity in their undergraduate research programs by actively recruiting students from underrepresented groups. The work will impact science infrastructure by disseminating research applications of modern instrumentation, for example, by training students to use NMR spectroscopy, a powerful and versatile tool in science and industry.
