Preparing for migration? The effects of photoperiod and exercise on muscle oxidative enzymes, lipid transporters, and phospholipids in white-crowned sparrows.
The extreme energetic demands of avian migration result in various physiological changes that can be observed during the migratory period. However, the degree to which birds alter muscle physiology in advance of migration has been poorly studied. We studied the effects of "migratory" photoperiod and exercise on metabolic enzymes, fatty acid transporter mRNA expression, and muscle phospholipid fatty acid composition in captive white-crowned sparrows (Zonotrichia leucophrys). Ten sparrows were held on short photoperiod (8L:16D) for 58 d then switched to long days (16L:8D) for 3 wk before sampling. Increased nightly activity indicated that the birds were indeed in migratory condition. Another 13 birds were held on short days during the entire experiment, and a subset (5) were exercised for 1 h every other day for the last 2 wk. "Migratory" photoperiod did not change the activities of citrate synthase, carnitine palmitoyl transferase, and 3-hydroxyacyl-CoA dehydrogenase or the expression of FAT/CD36, FABPpm, and H-FABP mRNA in pectoralis muscle, suggesting that these cannot be increased in advance of migratory flight. Docosahexaenoic acid increased in pectoralis muscle phospholipids with exercise but was negatively correlated with catabolic enzyme activity, indicating that the presence of this fatty acid may not aid migratory performance as suggested by other studies.
Price
Edwin R
ER
Division of Biological Sciences, University of Montana, Missoula, Montana 59812; 2Department of Biology, University of Western Ontario, London, Ontario N6A5B7, Canada. eprice3@uwo.ca
McFarlan
Jay T
JT
Guglielmo
Christopher G
CG
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism; D050612:Fatty Acid Transport Proteins / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000201:enzymology / Q000502:physiology; D010743:Phospholipids / Q000032:analysis*; D017440:Photoperiod; D010805:Physical Conditioning, Animal / Q000502:physiology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D020308:Songbirds / Q000502:physiology*
D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids; D008055:Lipids; D010743:Phospholipids; D012333:RNA, Messenger; D015094:3-Hydroxyacyl CoA Dehydrogenases; D007770:L-Lactate Dehydrogenase; D002950:Citrate (si)-Synthase