Exposure of high-light-grown cultures of <i>Chlorella vulgaris</i> to darkness inhibits the relaxation of excitation pressure: uncoupling of the redox state of the photosynthetic electron transport chain and phenotypic plasticity
Bibliographic record
Abstract
Chlorella vulgaris acclimated to high light (HL) conditions exhibited a pale-green phenotype characterized by reduced chlorophyll and light harvesting polypeptide abundance compared with the dark green phenotype of the control, low-light-grown (LL) cultures. We hypothesized that if chloroplast redox status was the sole regulator of phenotype, exposure to darkness should cause reversion of the HL to LL phenotype. Surprisingly, HL cells transferred to darkness or dim light failed to green. Thus, phenotypic reversion is light-dependent with an optimal photon flux density (PFD) of 110 μmol photons·m−2·s−1. HL cells shifted to this PFD exhibited increased chlorophyll and light harvesting polypeptide abundance, which were inhibited by 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone but not by 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea. We conclude that photoacclimation of HL-grown cells to LL is governed by the redox state of the intersystem photosynthetic electron transport chain (PETC) at this PFD. At lower light levels, cells maintained the HL phenotype, despite an oxidized status of the PETC. Because 110 μmol photons·m−2·s−1 was the optimal PFD for protochlorophyllide oxidoreductase accumulation, we suggest that stabilization of light-harvesting polypeptides by chlorophyll binding may also govern photoacclimation in C. vulgaris. The possible role of the metabolic balance between respiration and photosynthesis is also discussed.
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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".