Acute Light Exposure Suppresses Circadian Rhythms in Clock Gene Expression
Bibliographic record
Abstract
Light can induce arrhythmia in circadian systems by several weeks of constant light or by a brief light stimulus given at the transition point of the phase response curve. In the present study, a novel light treatment consisting of phase advance and phase delay photic stimuli given on 2 successive nights was used to induce circadian arrhythmia in the Siberian hamster ( Phodopus sungorus). We therefore investigated whether loss of rhythms in behavior was due to arrhythmia within the suprachiasmatic nucleus (SCN). SCN tissue samples were obtained at 6 time points across 24 h in constant darkness from entrained and arrhythmic hamsters, and per1, per2 , bmal1, and cry1 mRNA were measured by quantitative RT-PCR. The light treatment eliminated circadian expression of clock genes within the SCN, and the overall expression of these genes was reduced by 18% to 40% of entrained values. Arrhythmia in per1, per2, and bmal1 was due to reductions in the amplitudes of their oscillations. We suggest that these data are compatible with an amplitude suppression model in which light induces singularity in the molecular circadian pacemaker.
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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 | 0.001 |
| 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".