Mechanisms of Seasonal Phenotypic Flexibility in Passerine Birds

小型鸟类调整其生理以科普季节性的高能量需求，但这些调整背后的细胞和分子机制知之甚少。高能量需求时期的一个例子是寒冷的冬季气候，这促进了小型鸟类产热能力和耐寒能力的增加，该模型构成了本研究的重点。在这个项目中，将调查小型鸟类对高能量需求季节性时期的两个突出调整。在细胞和分子水平上调节飞行肌肉的大小的增加，这与颤抖产热能力的增加以及肌肉使用脂肪作为燃料的能力的增加有关。生物化学和分子方法将用于表征控制肌肉生长和脂肪使用的途径中的关键潜在调节点的调整。这些研究将集中在肌肉生长抑制素，一个在哺乳动物和鸟类肌肉大小的突出调节，和蛋白质参与运输脂肪进入和肌肉细胞内。肌肉生长抑制素和脂肪转运蛋白水平的变化将与高能量需求和肌肉产热能力提高的时期相关。这些实验还将区分温度和日照长度在驱动肌肉大小和脂肪使用的季节性调整中的相对作用。这些研究将显著提高对以下问题的理解：（1）小型鸟类对能量需求季节性变化的生理机制;（2）环境线索如何作为生理调整的信号;（3）小型鸟类和一般动物适应气候变化的生理能力。该项目将为一名博士后研究员、一名博士生和一名研究员提供研究机会和培训。学生和几个本科生。已制定计划，招募美洲原住民学生参加该项目。

Small birds adjust their physiology to cope with seasonal periods of high energy demands, but the cellular and molecular mechanisms underlying these adjustments are poorly understood. One example of a period of high energy demand is cold winter climates, which promote increases in heat production capacity and cold tolerance in small birds, and this model forms the focus of this study. In this project, two prominent adjustments of small birds to seasonal periods of high energy demand will be investigated. An increase in the size of the flight muscles, which is associated with an increase the capacity for shivering heat production, and an increase in the capacity for muscles to use fat as fuel, are regulated at the cellular and molecular levels. Biochemical and molecular approaches will be used to characterize adjustments in key potential regulatory points in pathways controlling muscle growth and fat use. These studies will focus on myostatin, a prominent regulator of muscle size in mammals and birds, and proteins involved in transporting fat into and within the muscle cell. Changes in the levels of myostatin and fat transporters will be correlated with periods of high energy demand and elevated capacities for muscular heat production. These experiments will also distinguish the relative roles of temperature and day-length in driving seasonal adjustments in muscle size and fat use. These studies will markedly improve understanding of:(1) the physiological mechanisms by which small birds respond to seasonal changes in energy demand; (2) how environmental cues function as signals for physiological adjustments; and (3) the capacity of small birds, and animals in general, to adjust physiology in response to changing climates. The project will provide research opportunities and training for a postdoctoral fellow, a Ph.D. student, and several undergraduate students. Plans are in place to recruit Native American students to participate in the project.