Differential posttranslational modification of mitochondrial enzymes corresponds with metabolic suppression during hibernation
Bibliographic record
Abstract
), cycle between two distinct metabolic states: torpor, where metabolic rate is suppressed by >95% and body temperature falls to ~5°C, and interbout euthermia (IBE), where both metabolic rate and body temperature rapidly increase to euthermic levels. Suppression of whole animal metabolism during torpor is paralleled by rapid, reversible suppression of mitochondrial respiration. We hypothesized that these changes in mitochondrial metabolism are regulated by posttranslational modifications to mitochondrial proteins. Differential two-dimensional gel electrophoresis and two-dimensional blue-native PAGE revealed differences in the isoelectric point of several liver mitochondrial proteins between torpor and IBE. Quadrupole time-of-flight LC/MS and matrix-assisted laser desorption/ionization MS identified these as proteins involved in β-oxidation, the tricarboxylic acid cycle, reactive oxygen species detoxification, and the electron transport system (ETS). Immunoblots revealed that subunit 1 of ETS complex IV was acetylated during torpor but not IBE. Phosphoprotein staining revealed significantly greater phosphorylation of succinyl-CoA ligase and the flavoprotein subunit of ETS complex II in IBE than torpor. In addition, the 75-kDa subunit of ETS complex I was 1.5-fold more phosphorylated in torpor. In vitro treatment with alkaline phosphatase increased the maximal activity of complex I from liver mitochondria isolated from torpid, but not IBE, animals. By contrast, phosphatase treatment decreased complex II activity in IBE but not torpor. These findings suggest that the rapid changes in mitochondrial metabolism in hibernators are mediated by posttranslational modifications of key metabolic enzymes, perhaps by intramitochondrial kinases and deacetylases.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".