Light‐harvesting complex gene expression is controlled by both transcriptional and post‐transcriptional mechanisms during photoacclimation in <i>Chlamydomonas reinhardtii</i>
Bibliographic record
Abstract
To compensate for increases in photon flux density (PFD), photosynthetic organisms possess mechanisms for reversibly modulating their photosynthetic apparatus to minimize photodamage. The photoacclimation response in Chlamydomonas reinhardtii was assessed following a 10‐fold increase in PFD over 24 h. In addition to a 50% reduction in the amount of chlorophyll and light‐harvesting complexes (LHC) per cell, the expression of genes encoding polypeptides of the light‐harvesting antenna were also affected. The abundance of Lhcb (a LHCII gene), Lhcb4 (a CP29‐like gene), and Lhca (a LHCI gene) transcripts were reduced by 65 to 80%, within 1–2 h; however, the RNA levels of all three genes recovered to their low‐light (LL) concentrations within 6–8 h. To determine the role of transcript turnover in this transient decline in abundance, the stability of all transcripts was measured. Although there was no change in the Lhcb or Lhca transcript turnover time, the Lhcb4 mRNA stability decreased 2.5‐fold immediately following high‐light (HL) stress. The Lhcb transcript abundance, on the other hand, was primarily dictated by the rate of transcription as determined using an arylsulphatase reporter gene system. Transcription from the Lhcb promoter was initially repressed in HL but recovered to the LL rate after 6–9 h. Interestingly, the LHCII and CP29 transcripts recovered to their prestress levels before there were significant reductions in the abundance of their corresponding polypeptides. Although there are short‐term alterations in transcription and transcript stability, the long‐term acclimation of the light‐harvesting antennae to HL occurs primarily at the translational level.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".