IOS: Acclimation to Hypoxia in Deer Mice

鹿鼠栖息在任何北美哺乳动物中最广泛的海拔分布，从海平面以下（死亡谷）到海拔4000米以上，在那里缺氧条件是正常的，鹿鼠必须适应它们的生理机能以满足氧气需求。最近的研究表明，先前描述的血红蛋白/遗传适应对氧气获取的影响非常有限，不足以单独解释鹿鼠在高海拔地区的成功和活动水平。鹿鼠也显示器官大小的变化（例如，心脏、肺），其沿着海拔梯度变化，并且与高水平活动所必需的改善的有氧性能相关。该项目将调查肺大小和功能的变化在多大程度上有助于观察到的适应高海拔的成年小鼠活动增加。学生将参与拟议研究的所有数据收集方面，并为本科课程的教育模块的开发做出贡献，并为南加州地区的公众和公民科学研讨会做出贡献。 这项研究的结果将通过在同行评审的期刊上发表和在科学会议上的演讲进一步传播。来自主要研究者实验室的初步数据表明，肺在高海拔地区输送氧气的能力是氧气级联的第一个关键限制，在鹿鼠中，肺有能力重塑以满足这种需求。 如果物种随着气候变暖而向上迁移，这种肺的可塑性将是高度适应的。 因此，该项目将测试一些动物在其一生中具有重塑肺结构和优化功能的能力的假设。 将通过组织学和生理学试验评估高海拔和低海拔适应小鼠之间心肺组织的变化。 改良的气体成分将用于对照（含氧量正常）和海拔适应动物肺性能的直接呼吸测定试验。 将测试肺体积、肺泡表面积、毛细血管密度和血气组成，以确定器官大小、结构和组成变化对高海拔适应的影响程度。 这项研究的结果将使我们了解由于气候变化而被迫迁移到更高海拔和恶劣或多变条件下的小型哺乳动物种群将如何科普他们的搬迁。

Deer mice inhabit the broadest altitudinal distribution of any North American mammal, from below sea level (Death Valley) to above 4000 m where hypoxic conditions are the norm and the deer mice must adapt their physiology to satisfy oxygen demand. It appears from recent research that previously described hemoglobin/genetic adaptations exert very modest effects on oxygen acquisition and are insufficient alone to explain the success and activity levels of deer mice at high altitude. Deer mice also display changes in organ sizes (e.g., heart, lung) that vary along the altitude gradient and are correlated with improved aerobic performance necessary for high levels of activity. This project will investigate the extent to which changes in lung size and function contribute to the observed increases in activity in adult mice acclimated to high altitude. Students will participate in all data collection aspects of the proposed research and contribute to the development of educational modules for undergraduate classes and outreach efforts to the public and citizen science workshops in the Southern California region. Results from the study will be further disseminated through publication in peer-reviewed journals and presentations at scientific meetings.Preliminary data from the principle investigator's lab suggests that the capacity of the lung to deliver oxygen at high altitude is the first critical limit in the oxygen cascade and that, in deer mice, the lung has the capacity to remodel to meet that demand. Such pulmonary plasticity would be highly adaptive if species are moving upward in elevation as the climate becomes warmer. This project will therefore test the hypothesis that some animals have the capacity to remodel lung architecture and optimize function throughout their lives. Changes in the cardio-pulmonary tissues between the high- and low-altitude acclimated mice will be assessed through histologic and physiologic assays. Modified gas composition will be used in direct respirometry tests of lung performance in control (normoxic) and altitude-acclimated animals. Lung volume, alveolar surface area, capillary density and blood gas composition will be tested to determine the extent to which organ size, architecture, and composition changes contribute to high altitude acclimation. Results from this study will inform our understanding of how small mammal populations that are forced to move to higher altitudes and harsh or variable conditions as a result of climate change will cope with their relocation.