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MitoPediaAlert2023 Archive

From Bioblast
Currently Answered Questions from the »Oroboros Ecosystem Agenda 2023 Archive«

Dec 2023

  • Dec- 18 Mo
Why add azide after ascorbate and TMPD when measuring Complex IV activity?

The O2 flux measured after the titration of ascorbate and TMPD is due to both CIV activity and autooxidation of these compounds. By subsequently inhibiting CIV activity with azide, the O2 flux due to autooxidation (chemical background) can be determined and subtracted from the initial measurement.
- »Complex IV«, »Chemical background « 
- communicated by »Grings Mateus« and »Timon-Gomez Alba« 

Nov 2023

  • Nov- 28 Tu
Protocols that SUIT your research question

Using Substrate-Uncoupler-Inhibitor-Titration protocols you can study mitochondrial respiratory control through a sequence of coupling and pathway control states induced by multiple titrations within a single experimental assay.
- »SUIT protocols« and »SUITbrowser« 
- communicated by »Schmitt Sabine« and »Timon-Gomez Alba« 

  • Nov- 10 Fr
When should I analyze my data as flux control ratios (FCRs)?

FCRs enable the comparison of samples normalized with various mitochondrial content parameters or when sample concentration is unknown. This is achieved by internally normalizing O2 fluxes in different respiratory states to the maximum flux in a common reference state.
- »Flux control ratio« 
- communicated by »Baglivo Eleonora« and »Timon-Gomez Alba« 

Oct 2023

  • Oct- 31 Tu
How to interpret cytochrome c efficiency

Stimulation of OXPHOS or ET capacity upon addition of cytochrome c provides evidence of cytochrome c loss, indicating damage of the mitochondrial outer membrane, which could be caused by sample preparation or pathological conditions.
- »Cytochrome c control efficiency« 
- communicated by »Schmitt Sabine« and »Leo Elettra« 

  • Oct- 10 Tu
What is the best fluorophore and concentration thereof for measuring mt-membrane potential?

It depends on sample characteristics - test the concentration of different fluorophores (safranin, TMRM and rhodamine 123) with your specific model to evaluate for inhibitory or uncoupling effects on respiration.
- »mt-membrane potential measurement« 
- communicated by »Grings Mateus« and »Cardoso Luiza« 

Sep 2023

  • Sep- 26 Tu
Do you know the difference between uncoupled, noncoupled and dyscoupled respiration?

Noncoupled respiration is induced experimentally for evaluation of ET capacity, while uncoupling and dyscoupling are respectively caused by physiological and pathological conditions that exert an influence on proton leak and slip.
- »Noncoupled respiration«, »BEC 2020.01« 
- communicated by »Leo Elettra« and »Cardoso Luiza« 

  • Sep- 05 Tu
Higher concentrations of oligomycin can decrease the ET capacity due to an inhibitory effect

Use a lower oligomycin concentration (5-10 nM) to measure LEAK respiration without impairing ET capacity and test to find the optimum concentration for your specific model.
- »Oligomycin in high-resolution respirometry«, »Doerrier 2018 Methods Mol Biol« 
- communicated by »Timon-Gomez Alba« and »Grings Mateus« 

Aug 2023

  • Aug- 22 Tu
Are pyruvate, glutamate, and malate substrates of Complex I?

No, NADH is a Complex I substrate. However, pyruvate, glutamate and malate are used in high-resolution respirometry as substrates for mitochondrial dehydrogenases to generate NADH in the mitochondrial matrix because NADH cannot cross the mitochondrial inner membrane.
- »NADH electron transfer-pathway state« and »Complex I« 
- communicated by »Cardoso Luiza« and »Grings Mateus«

  • Aug- 01 Tu
Respiration might be inhibited in the presence of high concentrations of some saccharides due to the Crabtree effect

It is observed in multiple cell types, such as tumor cells, bacteria or yeast, and it can be measured using SUIT-003 protocols.
- »Crabtree effect«, »SUIT-003« 
- communicated by »Timon-Gomez Alba« and »Leo Elettra« 

Jul 2023

  • Jul- 25 Tu
Body mass excess (BME) or body mass index (BMI)?

BME provides an evidence-based index of underweight, overweight and obesity across all heights and ages, in contrast to BMI. Try our BME calculator.
- »Body mass excess calculator« and »Body mass excess« 
- communicated by »Timon-Gomez Alba« and »Cecatto Cristiane«

  • Jul- 12 We
Is the ambiguity crisis a contemporary crisis comparable to the credibility or reproducibility crisis?

This is discussed in Gnaiger E (2023) Complex II ambiguities ― FADH2 in the electron transfer system.
- »MitoPedia: Ambiguity crisis«

  • Jul- 11 Tu
Here is a system of terms and abbreviations for mitochondrial respiratory pathway and coupling control states.

Although states and rates are distinguished by different symbols for coupling control states, such a distinction is not suggested for pathway control states and rates to avoid handing and overwhelming number of different symbols.
- »MitoPedia: Pathway and coupling control states«

  • Jul- 04 Tu
The function of mitochondrial respiratory supercomplexes is still under discussion

Although their structure has been described in different species, their function is still unclear. Come to MiPschool 2023 to find out about the latest discoveries.
- »Respiratory complexes and supercomplexes« and »MiPschool 2023« 
- communicated by »Timon-Gomez Alba« and »Cecatto Cristiane«

Jun 2023

  • Jun- 20 Tu
Decline of mitochondrial fitness in overweight states is a biomarker of the systemic mitObesity syndrome, providing a mechanistic link between common obesity and associated chronic comorbidities.

Body mass excess provides an evidence-based index of underweight, overweight and obesity across all heights and ages, applicable to all populations for which the healthy reference baseline is established.
- »Body mass excess and mitObesity«

May 2023

  • May- 31 We
Measuring fatty acid oxidation (FAO)-linked respiration requires a low concentration of malate

In the absence of malate, accumulation of Acetyl-CoA inhibits FAO.
- »Fatty acid oxidation pathway control state«, »Mitochondrial Pathways: Chapter 5« 
- communicated by »Cecatto Cristiane« and »Cardoso Luiza« 

Mar 2023

  • Mar- 14 Tu
Do you know the different ways to adjust oxygen concentration in the Oroboros O2k?

- »Setting the oxygen concentration«

Jan 2023

  • Jan- 16 Mo
Gnaiger 2020 BEC MitoPathways What is ROUTINE respiration?

ROUTINE respiration is the respiratory activity of living (non-permeabilized) cells in the physiological coupling state, which is controlled by cellular energy demand, energy turnover and the degree of coupling to phosphorylation.
- »Gnaiger 2020 BEC MitoPathways - Chapter 2.4« 
- communicated by »Schmitt Sabine«