Active transport of CO2 and bicarbonate is induced in response to external CO2 concentration in the green alga Chlorella kessleri
Bibliographic record
Abstract
The time-course of induction of CO(2) and HCO(3)- transport has been investigated during the acclimation of high CO(2)-grown Chlorella kessleri cells to dissolved inorganic carbon (DIC)-limited conditions. The rate of photosynthesis of the cells in excess of the uncatalysed supply rate of CO(2) from HCO(3)- was taken as an indicator of HCO(3)- transport, while a stimulation of photosynthesis on the addition of bovine carbonic anhydrase was used as an indicator of CO(2) transport. The maximum rate of photosynthesis (Pmax) was similar for high CO(2)-grown and low CO(2)-grown cells, but the apparent whole cell affinity for DIC and CO(2) of high CO(2)-grown cells was found to be about 30-fold greater than in air-grown cells, which indicates a lower affinity for DIC and CO(2). It was found that HCO(3)- and CO(2) transport were induced in 5.5 h in cells acclimating to air in the light and in the presence and absence of 21% O(2), which indicates that a change in the CO(2)/O(2) ratio in the acclimating medium does not trigger induction of DIC transport. No active DIC transport was detected in high CO(2)-grown cells maintained on high CO(2) for 5.5 h in the presence of 5 mM aminooxyacetate, an aminotransferase inhibitor. These results indicate no involvement of photorespiration in triggering induction. Active DIC transport induction was inhibited in cells treated with 5 microgram ml(-1) cycloheximide, but was unaffected by chloramphenicol treatment, indicating that the induction process requires de novo cytoplasmic protein synthesis. The total DIC concentration eliciting the induction and repression of CO(2) and HCO(3)- transport was higher at pH 7.5 than at pH 6.6. The concentrations of external CO(2) required for the induction and repression of DIC transport were 0 and 120 microM, respectively, and was independent of the pH of the acclimation medium. Prolonged exposure to a critical external CO(2) concentration elicits the induction of DIC transport in C. kessleri.
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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".