OXYGEN CONSUMPTION ASSOCIATED WITH FERRIC REDUCTASE ACTIVITY AND IRON UPTAKE BY IRON‐LIMITED CELLS OF <i>CHLORELLA KESSLERI</i> (CHLOROPHYCEAE)
Bibliographic record
Abstract
Plasma membrane ferric reductase activity was enhanced 5‐fold under iron limitation in the unicellular green alga Chlorella kessleri Fott et Nováková. Furthermore, ferric reductase activity in iron‐limited cells was approximately 50% higher in the light than in the dark. In contrast, iron uptake rates of iron‐limited cells were unaffected by light versus dark treatments. Rates of iron uptake were much lower than rates of ferric reduction, averaging approximately 2% of the dark ferric reduction rate. Ferric reduction was associated with an increased rate of O 2 consumption in both light and dark, the increase in the light being approximately 1.5 times as large as in the dark. The increased rate of O 2 consumption could be decreased by half by the addition of catalase, indicating that H 2 O 2 is the product of the O 2 consumption and that the increased O 2 consumption is nonrespiratory. The stimulation of O 2 consumption was almost completely abolished by the addition of bathophenanthroline disulfonate, a strong chelator of Fe 2 + . Anaerobic conditions or the presence of exogenous superoxide dismutase affected neither ferric reduction nor iron uptake. We suggest that the O 2 consumption associated with ferric reductase activity resulted from superoxide formation from the aerobic oxidation of Fe 2 + , which is the product of ferric reductase activity. At saturating concentrations of Fe 3 + chelates, ferric reductase activity is much greater than the iron uptake rate, leading to rapid oxidation of Fe 2 + and superoxide generation. Therefore, O 2 consumption is not an integral part of the iron assimilation process.
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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) | 0.001 | 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 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".