Mechanisms of Seasonal Phenotypic Flexibility in Passerine Birds

小型鸟类调整它们的生理机能以应对高能量需求的季节性时期，但这些调整背后的细胞和分子机制尚不清楚。高能量需求时期的一个例子是寒冷的冬季气候，这促进了小型鸟类的产热能力和耐寒性的增加，这一模型构成了本研究的重点。在这个项目中，将研究两个突出的小型鸟类对高能量需求季节的调整。飞行肌肉大小的增加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，这是在细胞和分子水平上受到调节的。生物化学和分子方法将用于描述控制肌肉生长和脂肪使用途径中关键潜在调节点的调节。这些研究将集中在肌肉生长抑制素上，肌肉生长抑制素是哺乳动物和鸟类肌肉大小的重要调节因子，以及参与将脂肪输送到肌肉细胞内的蛋白质。肌肉生长抑制素和脂肪转运蛋白水平的变化与高能量需求和肌肉产热能力的提高有关。这些实验还将区分温度和白天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方面的认识：(1)小鸟对能量需求季节性变化的生理反应机制；(2)环境线索如何作为生理调节的信号；(3)小型鸟类和一般动物适应气候变化的生理调节能力。该项目将为一名博士后、一名博士生和几名本科生提供研究机会和培训。招募印第安学生参与该项目的计划已经到位。

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.