Circadian photosynthetic reductant flow in the dinoflagellate <i>Lingulodinium</i> is limited by carbon availability
Bibliographic record
Abstract
Circadian rhythms are the observed outputs of endogenous daily clocks and are thought to provide a selective advantage to cells adapted to daily light/dark cycles. However, the biochemical links between the clock and the overt rhythms in cell physiology are generally not known. Here, we examine the circadian rhythm in O₂ evolution by cultures of the dinoflagellate Lingulodinium, a rhythm previously ascribed to rhythmic electron flow through photosystem II. We find that O₂ evolution rates increase when CO₂ concentrations are increased, either following addition of DIC or a rapid decrease in culture pH. In medium containing only nitrate as an electron acceptor, O₂ evolution rates mirror the circadian rhythm of nitrate reductase activity in the cells. Furthermore, competition between photosynthetic electron flow to carbon and to nitrate varies in its relative efficiency through the day-night cycle. We also find, using simultaneous and continuous monitoring of pH and O₂ evolution rates over several days, that while culture pH is normally rhythmic, circadian changes in rates of O₂ evolution depend not on the external pH but on levels of internal electron acceptors. We propose that the photosynthetic electron transport rhythm in Lingulodinium is driven by the availability of a reductant sink.
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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) | 0.000 | 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".