Fifty years of research on the “Bicarbonate effect” in photosystem II: A mini-review
Bibliographic record
Abstract
Cyanobacteria, algae, and plants fix CO2 in photosynthesis by utilizing the chemical energy generated in the light reaction. Photosystem II (PS II) plays a vital role in the photosynthetic energy fixation and oxygen evolution. Since the discovery of the stimulatory effect of CO2 on the Hill reaction (non-cyclic electron transfer in the light reaction), researchers from different laboratories around the world have shared their perspectives on this unique role of CO2. After approximately twenty-eight years of confusion regarding the role of CO2 in photosynthesis (dating back to James Franck's 1945 finding of increased oxygen evolution in the presence of CO2; Franck J (1945) Reviews of Modern Physics, 17:112-119), Alan Stemler and Govindjee from the University of Illinois at Urbana-Champaign (UIUC) established, in 1973, the effect of bicarbonate (HCO3-) on PS II but were unable to pinpoint the exact binding site. Ongoing research in Govindjee's laboratory and other research facilities worldwide (e.g., Canada, China, Israel, Finland, Switzerland, France, Germany, and The Netherlands) has predominantly focused on the effect of HCO3- on the (electron) acceptor side of PS II. However, key suggestions have been made regarding the effect of HCO 3- on the electron donor side (of PS II) by Alan Stemler (USA) and Vyacheslav Klimov (Russia). Yanyou Wu (China) has also put forth an argument suggesting that bicarbonate may partly serve as a source of oxygen in the light reaction of photosynthesis. In this review, we provide a brief historical account of the conceptual progression of the “bicarbonate effect” and present current perspectives on both the (electron) acceptor and donor sides of PS II. Additionally, we briefly discuss the prevailing opinion on the carbonic anhydrase-like function of PS II for CO2 hydration in oxygenic photosynthesis.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.004 | 0.004 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".