Difference between revisions of "Mathers 2017 J Comp Physiol B"
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|year=2017 | |year=2017 | ||
|journal=J Comp Physiol B | |journal=J Comp Physiol B | ||
|abstract=Small hibernators cycle between periods of torpor, with body temperature (T<sub>b</sub>) approximately 5 °C, and interbout euthermia (IBE), where T<sub>b</sub> is approximately 37 °C. During entrance into a torpor bout liver mitochondrial respiration is rapidly suppressed by 70 % relative to IBE. We compared activities of electron transport system ( | |abstract=Small hibernators cycle between periods of torpor, with body temperature (T<sub>b</sub>) approximately 5 °C, and interbout euthermia (IBE), where T<sub>b</sub> is approximately 37 °C. During entrance into a torpor bout liver mitochondrial respiration is rapidly suppressed by 70 % relative to IBE. We compared activities of electron transport system (ET-pathway) complexes in intact liver mitochondria isolated from 13-lined ground squirrels (''Ictidomys tridecemlineatus'') sampled during torpor and IBE to investigate potential sites of this reversible metabolic suppression. Flux through complexes I-IV and II-IV was suppressed by 40 and 60 %, respectively, in torpor, while flux through complexes III-IV and IV did not differ between torpor and IBE. We also measured maximal enzyme activity of ET-pathway enzymes in homogenized isolated mitochondria and whole liver tissue. In isolated mitochondria, activities of complexes I and II were significantly lower in torpor relative to IBE, but complexes III, IV, and V did not differ. In liver tissue, only activity of complex II was suppressed during torpor relative to IBE. Despite the significant differences in both ET-pathway flux and maximal activity, the protein content of complexes I and II did not differ between torpor and IBE. These results suggest that the rapid, reversible suppression of mitochondrial metabolism is due to regulatory changes, perhaps by post-translational modification during entrance into a torpor bout, and not changes in ET-pathway protein content. | ||
|keywords=Metabolic suppression, Mitochondria, Mitochondrial respiration, Oxidative phosphorylation | |keywords=Metabolic suppression, Mitochondria, Mitochondrial respiration, Oxidative phosphorylation | ||
|editor=[[Kandolf G]] | |editor=[[Kandolf G]] | ||
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}} | }} | ||
{{Labeling | {{Labeling | ||
|area=Respiration | |area=Respiration, Comparative MiP;environmental MiP | ||
|injuries=Temperature | |injuries=Temperature | ||
|organism=Other mammals | |organism=Other mammals | ||
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|enzymes=Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase | |enzymes=Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase | ||
|couplingstates=LEAK, OXPHOS | |couplingstates=LEAK, OXPHOS | ||
|pathways=N, S, CIV, ROX | |pathways=N, S, DQ, CIV, ROX | ||
|instruments=Oxygraph-2k | |instruments=Oxygraph-2k | ||
|additional= | |additional=2017-07, | ||
}} | }} |
Latest revision as of 11:27, 13 November 2017
Mathers KE, McFarlane SV, Zhao L, Staples JF (2017) Regulation of mitochondrial metabolism during hibernation by reversible suppression of electron transport system enzymes. J Comp Physiol B 187:227-34. |
Mathers KE, McFarlane SV, Zhao L, Staples JF (2017) J Comp Physiol B
Abstract: Small hibernators cycle between periods of torpor, with body temperature (Tb) approximately 5 °C, and interbout euthermia (IBE), where Tb is approximately 37 °C. During entrance into a torpor bout liver mitochondrial respiration is rapidly suppressed by 70 % relative to IBE. We compared activities of electron transport system (ET-pathway) complexes in intact liver mitochondria isolated from 13-lined ground squirrels (Ictidomys tridecemlineatus) sampled during torpor and IBE to investigate potential sites of this reversible metabolic suppression. Flux through complexes I-IV and II-IV was suppressed by 40 and 60 %, respectively, in torpor, while flux through complexes III-IV and IV did not differ between torpor and IBE. We also measured maximal enzyme activity of ET-pathway enzymes in homogenized isolated mitochondria and whole liver tissue. In isolated mitochondria, activities of complexes I and II were significantly lower in torpor relative to IBE, but complexes III, IV, and V did not differ. In liver tissue, only activity of complex II was suppressed during torpor relative to IBE. Despite the significant differences in both ET-pathway flux and maximal activity, the protein content of complexes I and II did not differ between torpor and IBE. These results suggest that the rapid, reversible suppression of mitochondrial metabolism is due to regulatory changes, perhaps by post-translational modification during entrance into a torpor bout, and not changes in ET-pathway protein content. • Keywords: Metabolic suppression, Mitochondria, Mitochondrial respiration, Oxidative phosphorylation • Bioblast editor: Kandolf G • O2k-Network Lab: CA London Staples JF
Labels: MiParea: Respiration, Comparative MiP;environmental MiP
Stress:Temperature Organism: Other mammals Tissue;cell: Liver Preparation: Intact cells, Isolated mitochondria Enzyme: Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase
Coupling state: LEAK, OXPHOS Pathway: N, S, DQ, CIV, ROX HRR: Oxygraph-2k
2017-07