Novel Roles of Urea in Amphibian Hibernation

这个项目是生理生态学家和细胞生理学家之间的合作，是对北方两栖动物和爬行动物极端耐寒性的生理机制的调查的继续。这一建议的论点是，尿素，两栖动物中的一种重要的渗透剂，可能具有重要的，以前没有文献记载的功能，在冬眠生理和抗寒性。这项调查的重点是林蛙（林蛙sylvatica），最广泛的研究所有抗冻脊椎动物。一组研究将证实并扩展一项初步发现，即林蛙在冬眠期间积累和保留尿素。这项工作将确定这些青蛙是否通过加速尿素生成来促进尿素积累，以及它们的组织是否含有某些已知作为尿素抵消剂的渗透剂（甲胺）。其他的研究将测试这一假设，即在陆地冬眠期间积累的尿素有助于冷冻生存，也许支持目前的观点，重叠适应的进化意义的冷冻保护和脱水耐受性。最后，这项工作将确定尿素积累是否有助于冬眠树蛙的代谢抑制，就像夏眠生物所假设的那样。将在整个动物水平、离体器官和红细胞Na+-K+泵活性中检查尿素的代谢效应。该项目将促进迈阿密大学（一所擅长本科教育和选择研究生课程的机构）和东伊利诺伊大学（一所拥有杰出本科研究和奖学金记录的RUI机构）的研究人员之间的新生研究合作。研究人员的研究和教育兴趣高度重叠，以及他们互补的背景和专业知识，将提高所有参与该项目的人员的研究生产力。此外，该项目还将促进迈阿密大学和东伊利诺伊大学学生的专业发展，让他们参与研究过程的所有阶段，并鼓励学生研究人员从内部和外部来源寻求资金;在同行评审的期刊上发表他们的工作;并在区域和国家会议上交流他们的研究结果。研究人员将通过积极从代表性不足的群体中招募学生来促进本科研究项目的更大多样性。这项工作将影响科学基础设施，传播现代仪器的研究应用，例如，通过培训学生使用核磁共振光谱学，一个强大的和多功能的工具，在科学和工业。

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.