IOS: Acclimation to Hypoxia in Deer Mice

在北美哺乳动物中，鹿鼠的海拔分布最广，从海平面以下(死亡谷)到海拔4000米以上，在那里缺氧是常态，鹿鼠必须调整自己的生理来满足氧气需求。最近的研究表明，以前描述的血红蛋白/遗传适应对氧气获取的影响非常小，单独不足以解释鹿鼠在高海拔地区的成功和活动水平。鹿小鼠的器官大小(如心脏、肺)也会随着海拔梯度的变化而变化，这与高水平活动所需的改善有氧运动能力有关。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适应高海拔的成年小鼠的活动增加。学生将参与拟议研究的所有数据收集方面，并为开发本科生课程的教育模块以及向南加州地区的公众和公民科学讲习班进行外联工作做出贡献。这项研究的结果将通过发表在同行评议的期刊上和在科学会议上发表进一步传播。来自首席研究员实验室的初步数据表明，肺在高海拔输送氧气的能力是氧级联反应的第一个关键极限，对于鹿鼠来说，肺有能力重塑以满足这一需求。如果随着气候变暖，物种在海拔上向上移动，这种肺部可塑性将是高度适应的。因此，该项目将检验这一假设，即一些动物有能力在一生中重塑肺结构并优化功能。将通过组织学和生理学分析来评估高海拔和低海拔习服小鼠之间心肺组织的变化。改良的气体成分将用于对照(常氧)和高原习服动物的肺功能的直接呼吸测量测试。将测试肺体积、肺泡表面积、毛细血管密度和血气成分，以确定器官大小、结构和成分变化对高原适应的贡献程度。这项研究的结果将告诉我们，由于气候变化而被迫迁徙到更高海拔和恶劣或可变条件的小型哺乳动物种群将如何应对它们的搬迁。

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.