Meeting Abstract

S6.4  Tuesday, Jan. 5  Move that fatty acid: fuel selection and transport in migrating birds and bats GUGLIELMO, Christopher G; Univ. of Western Ontario cguglie2@uwo.ca

My title emphasizes the great importance of fatty acid transport to successful non-stop migratory flight. Although fat is the most energy dense metabolic fuel, the insolubility of its component fatty acids makes them difficult to transport to working muscles fast enough to support the highly aerobic exercise required to fly. I will discuss recent evidence that migratory birds appear to deal with this by expressing large amounts of fatty acid transport proteins on the muscle membranes (FAT/CD36 and FABPpm) and in the cytosol (H-FABP). There is also evidence that through endogenous mechanisms and/or diet selection, migratory birds may alter the fatty acid composition of the fat stores and muscle membranes to improve endurance flight performance. I will review the evidence regarding fatty acid chain length, degree of unsaturation, and placement of double bonds (n-6 and n-3) on the rate of mobilization of fatty acids from adipose tissue, utilization of fatty acids by muscles, and whole animal performance. Protein stores are also very important to sustained migratory flight because they are catabolized for gluconeogenesis, key metabolic intermediates, and water. I will discuss the conditions under which protein stores can limit flight duration before fat stores are exhausted. Migratory bats provide an interesting example of evolutionary convergence with birds. I will discuss their potential similarities and differences in physiology and behaviour with birds, and recent attempts to study their migration physiology.