Mitochondrial marker

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MitoPedia

Mitochondrial marker

Description

Mitochondrial markers are structural or functional properties that are specific for mitochondria. A structural mt-marker is the area of the inner mt-membrane or mt-volume determined stereologically, which has its limitations due to different states of swelling. If mt-area is determined by electron microscopy, the statistical challenge has to be met to convert area into a volume. When fluorescent dyes are used as mt-marker, distinction is necessary between mt-membrane potential dependent and independent dyes. mtDNA or cardiolipin content may be considered as a mt-marker. Mitochondrial marker enzymes may be determined as molecular (amount of protein) or functional properties (enzyme activities). Respiratory capacity in a defined respiratory state of a mt-preparation can be considered as a functional mt-marker, in which case respiration in other respiratory states is expressed as flux control ratios. » MiPNet article

Abbreviation: mt-marker

Reference: Gnaiger 2014 MitoPathways


MitoPedia concepts: MiP concept 


MitoPedia methods: Respirometry, Fluorometry, Spectrophotometry 



MitoPedia topics: Enzyme 

Mitochondrial markers and expression of mitochondrial respiration

Publications in the MiPMap
Gnaiger E (2014) Mitochondrial markers and expression of mitochondrial respiration. Mitochondr Physiol Network 2014-07-26.

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Oroboros (2014) MiPNet

Abstract: Respiratory performance capacity of an organism, tissue or cell may change due to a change in size, concentration of functional elements (biomarker density) or element function (mt-specific function).


O2k-Network Lab: AT Innsbruck Gnaiger E


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HRR: Theory 


Biomarkers

In the example, Vc is the cell volume (cultured cells). From Gnaiger 2014 MitoPathways.
Markers for size are volume, mass, area. If mass is not expressed as total mass but as protein mass, then a physical marker of size is replaced by a biochemical marker. In isolated mitochondria, protein can be determined as a measure of amount of mitochondria or mt-concentration [mg mt-protein/ml]. However, protein cannot be used as a mt-biomarker in other mitochondrial preparations.
Determination of the size of a system under investigation always requires definition of the system. The system (subject) whose phenotype is studied may be an organism, a tissue or a cell. The biochemical marker total protein can be replaced by a specific protein, e.g. by a marker enzyme.[1] A biomarker can be considered as a functional element. Expressing performance (IO2, oxygen flow per biological system) per size yields specific performance (JO2, oxygen flux = flow per system size) in an unstructured analysis.[2]
A biomarker introduces a structural (and functional) element into the analysis. Therefore, expressing performance (IO2) per functional element (biomarker) yields marker-specific performance (Jmt,O2, mt-specific oxygen flux = flow per mt-marker) in a structured analysis.[3]
When replacing an enzyme activity by the respiratory activity in a defined respiratory state as a biomarker, then flow per mt-marker becomes a flux control ratio (FCR).[4],[5] Expressing structure by functional markers is without problem as long as the structure in question does not undergo any functional (qualitative) changes.

References

  1. Renner K, Amberger A, Konwalinka G, Kofler R, Gnaiger E (2003) Changes of mitochondrial respiration, mitochondrial content and cell size after induction of apoptosis in leukemia cells. Biochim Biophys Acta 1642: 115-23. »PMID: 12972300
  2. Gnaiger E (1993) Nonequilibrium thermodynamics of energy transformations. Pure Appl Chem 65: 1983-2002. »Open Access
  3. Gnaiger E (2014) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 4th ed. Mitochondr Physiol Network 19.12. Oroboros MiPNet Publications, Innsbruck: 64 pp. »Open Access
  4. Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int J Biochem Cell Biol 41: 1837-45. »PMID: 19467914
  5. Pesta D, Hoppel F, Macek C, Messner H, Faulhaber M, Kobel C, Parson W, Burtscher M, Schocke M, Gnaiger E (2011) Similar qualitative and quantitative changes of mitochondrial respiration following strength and endurance training in normoxia and hypoxia in sedentary humans. Am J Physiol Regul Integr Comp Physiol 301: R1078–87. »Open Access
» O2k-Protocols: mitochondrial and marker-enzymes