Metabolic fuel selection: exercise and cold exposure

这项工作的目的是研究动物在长时间运动或寒冷暴露期间如何管理它们的能量储备。长距离迁徙的鸟类在运动过程中有一种非凡的能力来使用脂肪储备，并在非常寒冷的环境中生存。然而，这些令人惊叹的运动员不间断地旅行数千公里的机制尚未得到阐明。在雪雁中，我们将测量自由飞行过程中从脂肪储备到工作肌肉的脂质转移速率，并怀疑它们比最好的哺乳动物运动员高出10倍以上。 我们还将确定它们如何保护身体的未隔热部分在冬天不被冻结。初步结果表明，它们的腿定期充满温暖的血液，它们的脚甚至可能拥有抗冻蛋白。我们最近还发现，一些候鸟使用特定的饮食脂质（从他们吃大量的小泥虾欧米伽-3脂肪酸）作为天然兴奋剂，以准备长途飞行。我们将测试这些脂质对圈养鹌鹑耐力的影响，并研究这些脂肪酸的作用机制。我们还将调查迁移红鲑鱼的脂质代谢，这些红鲑鱼在弗雷泽河中逆流而上到达产卵地。除了增进对长途移徙者生理学的了解外，这项工作在以下领域具有重要意义：了解脊椎动物燃料选择策略的演变，表征脂质代谢的新的基本方面，治疗人类肥胖，寻找新的方法来提高人类运动员的表现，以及制定野生动物保护政策（保护重要的候鸟栖息地，这些栖息地提供独特的饮食脂质）。

The goal of this work is to investigate how animals manage their energy reserves during prolonged exercise or cold exposure. Long-distance migrant birds have a remarkable ability to use fat reserves during locomotion and to survive in very cold environments. However, the mechanisms used by these amazing athletes to travel non-stop for thousands of kilometers have not been elucidated. In snow geese, we will measure rates of lipid transfer from adipose reserves to working muscles during free flight and suspect that they are more than 10 times higher than in the best mammalian athletes. We will also determine how they protect uninsulated parts of their body from freezing in the winter. Preliminary results suggest that they flood their legs with warm blood at regular intervals and that they might even possess antifreeze proteins in their feet. We have also recently discovered that some migrant shorebirds use specific dietary lipids (omega-3 fatty acids from small mud shrimps they eat in large quantitites) as natural doping agents to prepare before long flights. We will test the effects of these lipids on the endurance capacity of captive quails and examine the mechanisms of action of these fatty acids. We will also investigate lipid metabolism in migrating sockeye salmon that swim upstream in the Fraser river to reach their spawning grounds. Besides improving knowledge of long-distance migrant physiology, this work has significant implications in the following areas: understanding the evolution of fuel selection strategies in vertebrates, characterizing new fundamental aspects of lipid metabolism, treating human obesity, finding new ways to increase the performance of human athletes, and formulating policies for wildlife conservation (protection of critical migrant bird habitats that provide unique dietary lipids).