Mechanism of coordination between cell and chloroplast division in unicellular algae
Bibliographic record
Abstract
Chloroplasts arose from a cyanobacterial endosymbiont. Most algae with a single or a few chloroplasts per cell synchronize chloroplast division with the host cell cycle. This synchronization is regulated via interactions between the cell and chloroplast. The onset of chloroplast division is regulated by S-phase-specific expression of the nuclear-encoded chloroplast division genes; however, in the unicellular alga Nannochloris bacillaris, one of the plastid division genes, FtsZ2, is expressed throughout the cell cycle. Plastid-dividing (PD) machinery usually forms a ring complex only during the division phase, although the number of the FtsZ rings, and not of PD rings, is increased in N. bacillaris cells under phosphate-enriched mixotrophic condition where the chloroplast DNA is excessively replicated. Therefore, among components of the PD machinery, only FtsZ ring formation is promoted by chloroplast DNA synthesis under certain conditions. During chloroplast division, the onset of chloroplast constriction allows the progression of cell cycle to metaphase. The blockage of PD machinery formation before its assembly arrests the cell cycle in prophase in the unicellular alga, Cyanidioschyzon merolae; however, once DRP5B is recruited to the chloroplast division site, the cell cycle progresses despite the failure of chloroplast fission. A similar phenomenon has been observed in the glaucophyte Cyanophora paradoxa suggesting that the mechanism of the chloroplast division checkpoint is established early in chloroplast acquisition.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".