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Title: Enzymatic and mitochondrial responses to 5 months of aerial exposure in the slender lungfish Protopterus dolloi
Authors: Staples, J.F.
Kajimura, M.
Wood, C.M.
Patel, M.
Ip, Y.K. 
McClelland, G.B.
Keywords: Aestivation
Ornithine-urea cycle
Oxidative phosphorylation
Issue Date: Aug-2008
Citation: Staples, J.F., Kajimura, M., Wood, C.M., Patel, M., Ip, Y.K., McClelland, G.B. (2008-08). Enzymatic and mitochondrial responses to 5 months of aerial exposure in the slender lungfish Protopterus dolloi. Journal of Fish Biology 73 (3) : 608-622. ScholarBank@NUS Repository.
Abstract: Mitochondrial respiration and activities of key metabolic enzymes from liver and white skeletal muscle were compared between control aquatic slender lungfish Protopterus dolloi, and those exposed to air for 5 months. Activities of citrate synthase, glycogen phosphorylase, phosphofructokinase and pyruvate kinase in liver were not affected by air-exposure. In muscle, air-exposure reduced citrate synthase and pyruvate kinase activities (relative to tissue wet mass) by 63 and 50%, respectively. Liver carnitine palmitoyl transferase activity (relative to mitochondrial protein) decreased by half following air-exposure, but there was no change in muscle. In mitochondria isolated from muscle, state 3 and state 4 respiration were reduced by 74 and 89%, respectively following air-exposure, but liver mitochondria were not affected. In liver, air-exposure increased activities of ornithine-urea cycle enzymes including glutamine synthase, carbamoyl-phosphate synthase III and arginase, by 1.9- to 4.2-fold. Carbamoyl-phosphate synthase III activity could not be detected in muscle, indicating that urea is not synthesized in this tissue. These data suggest that skeletal muscle metabolism is downregulated in air-exposure, conserving energy and protein during a period when the animals cannot forage. In contrast, ATP production capacities in the liver are maintained, and this may permit expensive urea biosynthesis to continue during aerial exposure. © 2008 The Authors.
Source Title: Journal of Fish Biology
ISSN: 00221112
DOI: 10.1111/j.1095-8649.2008.01955.x
Appears in Collections:Staff Publications

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