MitoPedia alert - 2020
- Currently Answered Questions from the »Oroboros Ecosystem Agenda«
Previous MitoPedia Alert 2020
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|| Flow or flux - what is the difference? |
Rate can be expressed both as flow (I) and flux (J). Flow is used if the sample X can be quantified as count (NX; the number of cells, organisms), and changes proportionally with the size of X. Flux is a size-independent quantity where the rate is expressed per mass or volume of sample.
- »BEC2020.1: Mitochondrial physiology« - Box 2. Metabolic flows and fluxes: vectoral, vectorial, and scalar
- communicated by »Cecatto Cristiane« and »Komlodi Timea« and »Gnaiger Erich«
|| LEAK respiration relates to intrinsic uncoupling. |
Non-phosphorylating LEAK respiration is measured in the absence of externally added uncouplers (i) in the absence of adenylates, (ii) after depletion of ADP, or (iii) after inhibition of ATP synthase or adenine nucleotide translocase.
- »BEC2020.1: Mitochondrial physiology« - Table 2. Terms on respiratory coupling and uncoupling
- communicated by »Komlodi Timea« and »Cecatto Cristiane« and »Gnaiger Erich«
|| How can you reduce the amount of biological sample needed for high-resolution respirometry? |
The O2k-sV-Module provides all the components necessary for a smaller operation volume (0.5 mL) whereby the sample amount used for measuring oxygen flux can be reduced.
- communicated by »Komlodi Timea« and »Schmitt Sabine«
|| Background H2O2 calibration in the Amplex® UltraRed (AmR) assay:|
A background H2O2 calibration is performed before addition of sample. This is required for (1) calculation of the chemical background fluorescence in our Excel analysis template, and (2) calculation AmR assay sensitivity, for quality control.
- »Background H2O2 calibration«
- communicated by »Komlodi Timea« and »Schmitt Sabine«
|| Are permeabilized muscle fibers (pfi) a reliable model for studying ROS production? |
High oxygen concentrations are needed to avoid oxygen limitation in pfi. However, high oxygen pressures may artificially increase ROS prodcution, including H2O2, making pfi a questionable model for ROS production.
- »Oxygen dependence of ROS production in pfi«
- communicated by »Komlodi Timea« and »Cardoso Luiza«
|| What is the limitation of State 3 respiration compared to OXPHOS capacity? |
OXPHOS capacity is defined as the maximal respiratory capacity in the OXPHOS state in the presence of kinetically-saturating concentration of ADP, Pi, fuel substrates and O2. However, State 3 as defined by Chance and Williams (1955) can lead to underestimation of OXPHOS capacity and overestimation of excess E-P capacity due to kinetic limitations of the phosphorylation system.
- »BEC: Mitochondrial physiology« - Table 3 and several figures.
- communicated by » Cecatto Cristiane « and » Komlodi Timea «
||Non-mitochondrial respiration or residual oxygen consumption (Rox)? — Concept-driven constructive terminology frames our perception.
After inhibition of electron-transfer (ET) pathways or in the absence of fuel substrates, both mitochondrial non-ET reactions and non-mitochondrial reactions contribute to residual oxygen consumption in mt-preparations and living cells.
- »BEC: Mitochondrial physiology« — Table 1: Rox induced by non-ET pathway oxidation reactions
||Photosynthesis efficiency is reduced by 25% in plants and algae due the metabolic process called photorespiration. |
||Chlororespiration is the phenomenon by which oxygen is consumed in the chloroplasts of plant cells: |
||Did you know that dithionite should not be used to control the oxygen concentration in experiments with biological samples? |
- » Dithionite«
||Celebrating World Oceans Day|
Would you like to measure the O2 flux that occurs during photosynthesis using the O2k and conduct experiments about primary productivity in aquatic ecosystems? Soon you will be able to with the PB-Module that we are developing as part of the H2020 NextGen-O2k project.
||Mitochondria show variable preferences for glutamate & malate or pyruvate & malate to support NADH-linked respiration, depending on species, tissues, and pathophysiological state. |
DatLab 7.4 provides a step-by-step guide through SUIT-008 and SUIT-014, which can be used in parallel to compare respiratory capacities supported by these NADH-linked fuel substrates.
-»SUIT-008« and »SUIT-014«
||Did you know that oxygen concentration in the O2k-Chamber can be decreased by injecting nitrogen gas? |
- »Nitrogen injection«
||As part of the H2020 SME NextGen-O2k project we are developing a PhotoBiology module that will allow to study the effect of different light intensities on O2 consumption and production.|
|| Is your mitochondrial preparation contaminated with other membranous organelles containing ATPases? |
DatLab 7.4 provides a step-by-step guide through the SUIT-024 as a quality control protocol of the mitochondrial preparation
||The optimum effective digitonin concentration for complete plasma membrane permeabilization without mitochondrial outer membrane damage. |
DatLab 7.4 provides a step-by-step guide through the SUIT-010 protocol to test the optimum digitonin concentration.
||Do you want to search the best SUIT protocol for your research questions? |
- Use the SUITbrowser: »SUITbrowser«
||The standardized coupling control protocol to explore the bioenergetics of living cells |
DatLab 7.4 provides a step-by-step guide through the SUIT-003 protocol and its extensions.
||Explore metabolic profiles and specific modulations of mitochondrial pathways in health and disease with SUIT reference protocols. |
- »RP1« and »RP2«
||Spermidine and other calorie restriction mimetics control autophagy and mitochondrial function. |
||What do metformin, melatonin and other bioactive mitObesity compounds have in common? |
- »MitObesity drugs«
||Did you ever think that units for body mass could be an issue? |
- »Body mass«
||Force and Energy: this we all need in the New Year - and MitoPedia may help to clarify the difference.