Constitutive expression of inducible Hsp70 is linked to natural shifts in skeletal muscle phenotype
Bibliographic record
Abstract
AIM: Constitutive expression of heat shock protein 70 (Hsp70) is elevated in frequently recruited, metabolically efficient rodent striated muscle. We aimed to assess the relative importance of muscle phenotype vs. increased contractile activity on this pattern of expression using the rat diaphragm, which undergoes a dramatic and sustained increase in recruitment with parturition and development. METHODS: Diaphragms were collected from rats of various ages (20 day fetus, 1 and 3 days, and 1, 3, 6 and 12 weeks postpartum; PP), and assessed for changes in oxidative capacity, Hsp70 and Type I myosin heavy chain (MHCI) (used as a marker of muscle phenotype changes). RESULTS: Oxidative capacity of the diaphragm (as indicated by citrate synthase activity) and whole body growth rate (% increase in body weight per week), factors thought to require chaperone activity, increased rapidly, peaked at 3-6 weeks PP and declined late in development. In contrast, at 1 week PP, increased contractile activity in the diaphragm had not altered the expression of Hsp70 protein or mRNA from fetal levels. Significant increases in Hsp70 were not observed until between 1 and 3 weeks, achieving their highest levels at 12 weeks PP. Both MHC I protein (r = 0.69, P = 0.001) and mRNA (r = 0.76, P = 0.001) were significantly correlated with their Hsp70 counterparts. CONCLUSIONS: Expression of Hsp70 in the developing diaphragm represents an adaptation associated with a shift towards a slower, more metabolically efficient adult phenotype rather than simply a response to contractile stress.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".