Comparison of skeletal muscle mitochondrial properties isolated by protease digestion and mechanical homogenization
Bibliographic record
Abstract
Skeletal muscle contains two heterogeneous mitochondrial subfractions located in the subsarcolemmal (SS) and intermyofibrillar (IMF) regions. Traditionally, the isolation of IMF mitochondria has required the use of limited protease (Nagarse) digestion. The purpose of this investigation was to compare the properties of SS with those of IMF mitochondria isolated by protease (PROT; 0.25mg/g tissue) or mechanical (MECH; Teflon‐glass, ~900 rpm) protocols. Protein yield was similar among IMF mitochondria obtained by PROT and MECH digestion compared to the SS subfraction, as were the respiratory control ratios (6–10), indicating the isolation of well‐coupled mitochondria independent of the procedure used. State 4 and 3 respiration rates in IMF PROT and IMF MECH mitochondria were 3‐5‐ and 2‐2.5‐fold greater than SS mitochondria, respectively. Membrane potential of IMF PROT and IMF MECH mitochondria were 55% lower and 12% higher compared to SS mitochondria. ROS production was 60–80% lower in IMF PROT and 30–45% lower in IMF MECH mitochondria during state 4 and state 3 respiration compared to the SS subfraction. Electron microscopy revealed that the MECH protocol produced IMF mitochondria which were less pure than with the PROT method. These data indicate that properties of SS and IMF subfractions remain distinct following IMF PROT and MECH isolation procedures. However, these established disparities between SS and IMF mitochondria are attenuated with MECH fractionation, which may be due in part to contamination by non‐mitochondrial constituents. Support from NSERC and HSFC.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".