Genomic and metabolic preparation of muscle in sockeye salmon Oncorhynchus nerka for spawning migration.
Prolonged endurance exercise and fasting are two major metabolic challenges facing Pacific salmon during spawning migrations that often occur over 1,000 km. Because both prolonged exercise and fasting stimulate the oxidation of lipids, particularly in heavily recruited tissues such as muscle, we sought to investigate the regulatory mechanisms that establish and maintain the capacity for substrate oxidation at four separate locations during the final 750 km of nonfeeding migration in sockeye salmon Oncorhynchus nerka. Transcript levels of multiple genes encoding for important regulators of lipid, carbohydrate, and protein oxidation as well as the activity of several important enzymes involved in lipid and carbohydrate oxidation were examined in red and white muscle. We found in both muscle types that the messenger RNA (mRNA) expression of carnitine palmitoyltransferase I isoforms, peroxisome proliferator-activated receptors α and β, and adenosine monophosphate-activated protein kinase β1 were all significantly higher at the onset compared to later stages of nonfeeding migration. However, the activities of β-hydroxyacyl-CoA dehydrogenase and citrate synthase were higher only early in migration and only in red muscle. Later in the migration and as muscle lipid stores were greatly depleted, the mRNA levels of hexokinase I and aspartate aminotransferase increased in white muscle. Overall, at the onset of migration, high transcript and metabolic enzyme activity levels in skeletal muscle of sockeye salmon may help support the high rates of lipid oxidation needed for endurance swimming. Furthermore, we suggest that the muscle capacity to use carbohydrates and proteins may be adjusted throughout migration on an as-needed basis to fuel burst exercise through very difficult hydraulic passages in the river and perhaps during mating activities.
Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada; 2Fisheries and Oceans Canada, Co-operative Resource Management Institute, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada; 3Department of Zoology and Faculty of Land and Food Systems, University of British Columbia, 2370-6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada.
Andrea J
AJ
Morash
Wilson
W
Yu
Christophe M R
CM
Le Moine
Jayme A
JA
Hills
Anthony P
AP
Farrell
David A
DA
Patterson
Grant B
GB
McClelland
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000235:genetics / Q000378:metabolism; D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001219:Aspartate Aminotransferases / Q000235:genetics / Q000378:metabolism; D001955:British Columbia; D002334:Carnitine O-Palmitoyltransferase / Q000235:genetics / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000235:genetics / Q000378:metabolism; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism; D050356:Lipid Metabolism / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism; D048068:PPAR-beta / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D012474:Salmon / Q000235:genetics / Q000378:metabolism*
D047493:PPAR alpha; D048068:PPAR-beta; D012333:RNA, Messenger; D015094:3-Hydroxyacyl CoA Dehydrogenases; D002334:Carnitine O-Palmitoyltransferase; D002950:Citrate (si)-Synthase; D001219:Aspartate Aminotransferases; D006593:Hexokinase; D055372:AMP-Activated Protein Kinases