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The molecular basis of aerobic metabolic remodeling differs between oxidative muscle and liver of threespine sticklebacks in response to cold acclimation

TitleThe molecular basis of aerobic metabolic remodeling differs between oxidative muscle and liver of threespine sticklebacks in response to cold acclimation
Publication TypeJournal Article
Year of Publication2010
AuthorsOrczewska, JI, Hartleben, G, O’Brien, KM
JournalAmerican Journal of Physiology – Regulatory, Integrative and Comparative Physiology
Volume299
PaginationR352-R364
Abstract

The molecular basis ofaerobic metabolic remodeling differs between oxidative muscle and liverof threespine sticklebacks in response to cold acclimation. Am J PhysiolRegul Integr Comp Physiol 299: R352–R364, 2010. First published April28, 2010; doi:10.1152/ajpregu.00189.2010.–-We sought to determinethe molecular basis of elevations in aerobic metabolic capacity in theoxidative muscle and liver of Gasterosteus aculeatus in response tocold acclimation. Fishes were cold- or warm-acclimated for 9 wk andharvested on days 1, 2, and 3 and weeks 1, 4, and 9 of cold acclimationat 8°C, and on day 1 and week 9 of warm acclimation at 20°C.Mitochondrial volume density was quantified using transmission electronmicroscopy and stereological techniques in warm- and coldacclimatedfishes harvested after 9 wk at 20 or 8°C. Changes inaerobic metabolic capacity were assessed by measuring the maximalactivity of citrate synthase (CS) and cytochrome-c oxidase (COX) infishes harvested throughout the acclimation period. Transcript levelsof the aerobic metabolic genes CS, COXIII, and COXIV, and knownregulators of mitochondrial biogenesis, including peroxisome proliferator-activated receptor- coactivators-1 and -1 (PGC-1 andPGC-1), nuclear respiratory factor-1 (NRF-1), and mitochondrialtranscription factor-A were measured in fishes harvested throughoutthe acclimation period using quantitative real-time PCR. The maximalactivities of CS and COX increased in response to cold acclimation inboth tissues, but mitochondrial volume density only increased inoxidative muscle (P 0.05). The time course for changes in aerobicmetabolic capacity differed between liver and muscle. The expressionof CS increased within 1 wk of cold acclimation in liver and wascorrelated with an increase in mRNA levels of NRF-1 and PGC-1.Transcript levels of aerobic metabolic genes increased later in oxidativemuscle, between weeks 4 and 9 of cold acclimation and werecorrelated with an increase in mRNA levels of NRF-1 and PGC-1.These results show that aerobic metabolic remodeling differs betweenliver and muscle in response to cold acclimation and may be triggeredby different stimuli.

DOI10.1152/ajpregu.00189.2010
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