Meeting Abstract

5.11  Thursday, Jan. 3  Expression of fatty acid uptake proteins in muscle tissue of white-throated sparrows (Zonotrichia albicollis) increases during migratory seasons. MCFARLAN, Jay T*; BONEN, Arend; GUGLIELMO, Christopher G; Univ. of Guelph, Guelph; Univ. of Guelph, Guelph; Univ. of Western Ontario, London mcfarlan@uoguelph.ca

Migratory birds are a unique model system to study lipid metabolism because they maintain high-intensity exercise for very long periods of time, using almost entirely fatty acids from adipose stores to fuel their long-distance flights. Uptake of fatty acids from the circulation into muscle tissue is largely facilitated by the proteins fatty acid translocase (FAT/CD36) and plasma membrane fatty acid binding protein (FABPpm). We investigated whether the expression of these proteins in muscle tissue changes in the white-throated sparrow (Zonotrichia albicollis) with migratory seasons, when compared to the wintering (non-migratory) season. FAT/CD36 and FABPpm expression increase 2- to 4-fold during migratory seasons. Heart-type fatty acid binding protein (H-FABP, FABPc, FABP3), an intracellular chaperone for lipids, has previously been observed to increase 2-fold in migratory birds and we confirmed this by measuring a 10-fold increase in H-FABP mRNA during migratory seasons. The magnitude of these increases during migration is well beyond the marginal increases in activity of key enzymes of fatty acid metabolism (citrate synthase, carnitine palmitoyl transferase, 3-hydroxy-acyl-CoA-dehydrogenase) observed in other migratory bird species. We are currently investigating the activity of these key enzymes in the same white-throated sparrows to determine if the increased supply of fatty acids for metabolism, and not the increased capacity of oxidative machinery, might have a greater role in permitting migratory flight.