Metabolic fuel selection: exercise and cold exposure

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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).