Conditional senescence in <i>Chlamydomonas reinhardtii</i> (Chlorophyceae)
Bibliographic record
Abstract
The mechanisms of microalgal senescence may play an important role in nutrient recycling and enhanced survival. However, the aging physiology of microalgae is an understudied phenomenon. To investigate the patterns of conditional senescence in Chlamydomonas reinhardtii P. A. Dangeard, we used a cell wall-less strain, transformed with a reporter gene to infer changes in photosynthetic gene expression. We examined plastid ultrastructure, photosynthetic function, and photoprotective mechanisms during aging in batch cultures. LHCII transcription levels decreased before the population entered stationary phase, and the characteristic transcriptional light-shift response was lost. A decline in photosynthetic proteins with a concomitant increase in the photoprotective protein, LHCSR, was observed over time. However, nonphotochemical quenching remained stable during growth and stationary phase, and then declined as alternative quenching mechanisms were up-regulated. Photosynthetic efficiency declined, while Fv/Fm remained stable until the death phases. As the culture progressed through stationary phase, disorganization of the chloroplast was observed along with an increase in cytoplasmic oil bodies. We also observed a partial recovery of function and proteins during the final death phase, and attribute this to the release of nutrients into the medium from cell lysis and/or active secretion while cells were senescing. Allowing open gas exchange resulted in high levels of sustained starch production and maintained maximum cell density, prolonging the stationary phase.
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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) | 0.000 | 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".