Regulation of the mTOR signaling network in hibernating thirteen-lined ground squirrels
Bibliographic record
Abstract
For many small mammals, survival over the winter months is a serious challenge because of low environmental temperatures and limited food availability. The solution for many species, such as thirteen-lined ground squirrels (Ictidomys tridecemlineatus), is hibernation, an altered physiological state characterized by seasonal heterothermy and entry into long periods of torpor that are interspersed with short arousals back to euthermia. During torpor, metabolic rate is strongly reduced to achieve major energy savings, and a coordinated depression of non-essential ATP-expensive functions such as protein synthesis takes place. This study examines the mammalian target of rapamycin (mTOR) signaling pathway, a crucial component of the insulin receptor network, over six stages of the torpor-arousal cycle of hibernation. Immunoblots showed that the phosphorylation state of mTOR(Ser2448) was strongly reduced in skeletal muscle (by 55%) during late torpor but increased by 200% during early arousal compared with euthermia. However, the phosphorylation state of this residue remained relatively constant in cardiac muscle during torpor but was enhanced during entrance into torpor and early arousal from torpor stages (by 2.9- and 3.2-fold, respectively). Phosphorylation states of upstream regulators of mTOR, p-Akt(Thr473) and p-TSC2(Thr1462), were also suppressed in skeletal muscle by 55 and 51%, respectively, during late torpor, as were selected downstream substrates--p-4E-BP1(Thr46) and p-S6(Ser235) contents dropped by 74 and 41%, respectively. Overall, the results indicate suppressed mTOR signaling in skeletal muscle, but not cardiac muscle, during torpor. By contrast, activation of mTOR and other components of the mTORC1 complex (p-PRAS40(Thr246) and GβL) occurred during early arousal in both skeletal and cardiac muscle.
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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 | 0.001 | 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".