CO<sub>2</sub>‐CONCENTRATING MECHANISMS OF THE POTENTIALLY TOXIC DINOFLAGELLATE <i>PROTOCERATIUM RETICULATUM</i> (DINOPHYCEAE, GONYAULACALES)<sup>1</sup>
Bibliographic record
Abstract
The low CO2 concentration in seawater poses severe restrictions on photosynthesis, especially on those species with form II RUBISCO. We found that the potentially toxic dinoflagellate Protoceratium reticulatum Clap. et J. Lachm. possesses a form II RUBISCO. To cast some light on the mechanisms this organism undergoes to cope with low CO2 availability, we compared cells grown at atmospheric (370 ppm) and high (5000 ppm) CO2 concentrations, with respect to a number of physiological parameters related to dissolved inorganic carbon (DIC) acquisition and assimilation. The photosynthetic affinity for DIC was about one order of magnitude lower in cells cultivated at high [CO2]. End‐point pH‐drift experiments suggest that P. reticulatum was not able to efficiently use HCO3− under our growth conditions. Only internal carbonic anhydrase (CA) activity was detected, and its activity decreased by about 60% in cells cultured at high [CO2]. Antibodies raised against a variety of algal CAs were used for Western blot analysis: P. reticulatum extracts only cross‐reacted with anti‐ß‐CA sera, and the amount of immunoreactive protein decreased in cells grown at high [CO2]. No pyrenoids were observed under all growth conditions. Our data indicate that P. reticulatum has an inducible carbon‐concentrating mechanism (CCM) that operates in the absence of pyrenoids and with little intracellular CO2 accumulation. Calculations on the impact of the CA activity to photosynthetic growth [CO2] suggest that it is an essential component of the CCM of P. reticulatum and is necessary to sustain the photosynthetic rates observed at ambient CO2.
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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) | 0.001 | 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".