Mechanisms of Seasonal Phenotypic Flexibility in Passerine Birds

小鸟调整它们的生理，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。一个高能量需求期的例子是寒冷的冬季气候，它促进了小鸟的产热能力和耐寒能力的增加，这个模型构成了本研究的重点。在这个项目中，将调查小鸟对高能源需求季节的两个显著调整。飞行肌肉大小的增加与颤抖产生热量的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调节的。生化和分子方法将被用来描述控制肌肉生长和脂肪使用的途径中关键潜在调节点的调整。这些研究将集中在肌肉抑制素，一种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和肌肉细胞内的蛋白质。肌肉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热产生能力增强的时期相关。这些实验还将区分温度和日长在推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理解：(1)小鸟对能量需求的季节性变化做出反应的生理机制；(2)环境信号如何作为生理调节的信号；以及(3)小鸟和一般动物对气候变化的生理调节能力。该项目将为一名博士后研究员、一名博士生和几名本科生提供研究机会和培训。招募美洲原住民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.