Document Detail

Thermal acclimation and regulation of metabolism in a reptile (Crocodylus porosus): the importance of transcriptional mechanisms and membrane composition.
MedLine Citation:
PMID:  19732017     Owner:  NLM     Status:  MEDLINE    
Energy metabolism is fundamental for animal fitness because it fuels locomotion, growth, and reproduction. Mitochondrial capacities often acclimate to compensate for negative thermodynamic effects. Our aim was to determine the importance of transcriptional regulation and membrane fatty acid composition in modulating oxidative capacities at body temperatures selected in a cold and a warm environment by a reptile (Crocodylus porosus). In the cool environment (mean selected T(b) = 21 degrees C), mRNA concentrations of the transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) and its coactivator PPARgamma coactivator 1 alpha (PGC-1alpha), as well as of the cytochrome c oxidase (COX) subunits COX1 and COX5, were significantly higher in the liver but not in skeletal muscle compared with animals in the warm environment (mean selected T(b) = 29 degrees C). F(O)F(1)-ATPase subunit alpha mRNA concentrations were significantly higher in both muscle and the liver in the cool animals. A positive relationship between PGC-1alpha and PPARgamma mRNA concentrations, with an indicator of mitochondrial density (16S rRNA) in muscle and COX and F(O)F(1)-ATPase subunit alpha mRNA concentrations in liver, suggest that these proteins regulate quantity increases of mitochondria during acclimation. The percent saturated fatty acids in liver membranes of cool animals was significantly lower, and the n3 fatty acid content was significantly higher, compared with in warm animals. The n3 fatty acid content was positively related to COX enzyme activity in the liver, and there was a negative relationship between n7 fatty acid content and COX activity in muscle. Hence, metabolic acclimation is mediated by both transcriptional regulation and membrane fatty acid composition. The importance of PGC-1alpha and PPARgamma in a reptile indicate that the mechanisms that regulate metabolism are conserved among vertebrates.
F Seebacher; S A Murray; P L Else
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Physiological and biochemical zoology : PBZ     Volume:  82     ISSN:  1537-5293     ISO Abbreviation:  Physiol. Biochem. Zool.     Publication Date:    2009 Nov-Dec
Date Detail:
Created Date:  2009-10-13     Completed Date:  2010-02-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100883369     Medline TA:  Physiol Biochem Zool     Country:  United States    
Other Details:
Languages:  eng     Pagination:  766-75     Citation Subset:  IM    
Integrative Physiology, School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.
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MeSH Terms
Acclimatization / physiology*
Alligators and Crocodiles / physiology*
Body Temperature
Cell Membrane / chemistry
Electron Transport Complex IV / metabolism
Energy Metabolism / physiology*
Fatty Acids / analysis
Liver / chemistry
PPAR gamma / metabolism
RNA, Ribosomal, 16S / analysis
Regression Analysis
Transcription, Genetic / physiology*
Reg. No./Substance:
0/Fatty Acids; 0/PPAR gamma; 0/RNA, Ribosomal, 16S; EC Transport Complex IV

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