Pattern of cellular quiescence over the hibernation cycle in liver of thirteen-lined ground squirrels
Bibliographic record
Abstract
Mammalian hibernation is a state of seasonal heterothermy that consists of long periods of torpor at low body temperature interspersed with short periods of arousal back to euthermia. Entry into the hypometabolic state of torpor is achieved via a strong coordinated reduction of energy expenditures, particularly ATP-expensive activities, such as transcription and translation. The present study analyzes the status of the cell cycle during hibernation in liver of thirteen-lined ground squirrels (Ictidomys tridecemlineatus) and examines the expression levels of cell cycle regulators over six stages of the torpor-arousal cycle. Immunoblot analysis showed that the protein expression levels of cyclin D1 and cyclin E were reduced in liver (by 31% and 48%, respectively) during long-term torpor; however, during arousal from torpor, PCR analysis showed an upregulation of cyclin D1 transcript levels of about 1.5-fold. Protein expression of cyclin A and cyclin B1 were also elevated (1.57-fold and 2.44-fold, respectively) during early arousal from torpor, and in addition, cyclin A2 transcript levels increased by about 1.8-fold during arousal. Protein levels of two CKIs, p15(INK4b) and p21(CIP1), each increased by about 1.4-fold during torpor, and transcript levels of p15(INK4b) also rose by 1.7-2.1 fold during torpor, whereas p21(CIP1) transcripts increased by 1.5-1.7-fold. A reduction in cyclin D and E protein expression coupled with upregulation of p15(INK4b) and p21(CIP1) inhibitors during torpor reflects markers of cell cycle arrest during hibernation. Elevated expression of cyclin A and B protein expression during arousal stages of torpor suggests cell cycle progression is reversibly arrested during torpor and is reinitiated upon return to euthermia.
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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".