Control of lipid metabolism and muscle hypertrophy by PPARs in Gray catbird annual life cycle

候鸟是自然界最有成就的运动员之一。这些鸟中的许多都要飞行几千英里，很少休息。除了时间和导航方面的挑战外，迁移的能源成本也非常高。候鸟的工作强度可能是环法自行车赛选手的两倍。由于这些鸟通常不会停下来加油，在出发前的几周，它们会沉迷于进食，体重迅速增加。增加的脂肪储存可能是他们体重的50%，相当于一个150磅的人在不到一个月的时间里增加了75磅。同样令人惊讶的是，在为迁徙做准备时，飞行肌肉的大小会增加，即使是在圈养的鸟类中也是如此。在这两种情况下，都需要对这些动物的正常解剖（结构）和生理（功能）进行重置，以满足迁移的要求。虽然人们对这些戏剧性的转变了解很多，但对它们是如何控制的却知之甚少。迁移准备的控制可能取决于一个被称为过氧化物酶体增殖激活受体（ppar）的基因调控家族，这是一种存在于所有脊椎动物中的调节蛋白。在哺乳动物中，ppar被研究得最多，它既控制脂肪组织中脂肪的储存，也控制肌肉中脂肪作为燃料的使用。调节其活性的药物正在开发中，用于治疗人类代谢紊乱。通过使用这些药物操纵PPAR活性，研究人员将探索PPAR在迁移中的作用。由于迁徙可能是任何动物对能量需求最深刻的挑战之一，研究人员将揭示新陈代谢及其调节的细节，同时揭示大自然的奇迹之一。此外，ppar通常会对饮食信号做出反应，因此鸟类可能会选择有助于刺激必要变化的食物。研究人员将与当地学校的学生合作，探索候鸟对本地植物的需求，并开发将栖息地和迁徙结合起来的课程，同时教授鸟类多样性。

Migratory birds are among nature's most accomplished athletes. Many of these birds undertake journeys of several thousand miles with little rest. In addition to the challenges of timing and navigation, the energy costs of migration are very high. Migrating birds operate at a level of effort that may be double that of a Tour de France bicycle racer. As these birds often do not stop to refuel, in the weeks before departure birds become obsessed with feeding and gain weight rapidly. Added fat stores may be 50% of their body weight, equivalent to a 150 pound human gaining 75 pounds in less than a month. Equally astonishing, flight muscle size increases in preparation for migration, even in birds kept inactive in captivity. In both cases, there is a resetting of normal anatomy (structure) and physiology (function) of these animals to match the requirements of migration. While much is known about these dramatic shifts, little is known about how they are controlled. Control of preparation for migration may lie with a family of gene regulators called peroxisome proliferator-activated receptors or PPARs, regulatory proteins found in all vertebrates. In mammals, where they have been most studied, PPARs control both the storage of fats in adipose tissue as well as the use of fats as fuel in muscle. Drugs that modulate their activity are in development for treatment of human metabolic disorders. By manipulating PPAR activity using these drugs, researchers will explore the roles of PPARs in migration. As migration may be one of the most profound challenges to energy demands in any animal, researchers will unveil details of metabolism and its regulation while shedding light on one of nature's marvels. Additionally, the PPARs normally respond to dietary signals, thus birds may be choosing foods that help to spur necessary changes. The researchers will work with local school children to explore the needs of migrating birds for native plants and develop curricula that brings habitat and migration together while teaching about avian diversity.