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 O2 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 O2 consumption could be decreased by half by the addition of catalase, indicating that H2O2 is the product of the O2 consumption and that the increased O2 consumption is nonrespiratory. The stimulation of O2 consumption was almost completely abolished by the addition of bathophenanthroline disulfonate, a strong chelator of Fe2+. Anaerobic conditions or the presence of exogenous superoxide dismutase affected neither ferric reduction nor iron uptake. We suggest that the O2 consumption associated with ferric reductase activity resulted from superoxide formation from the aerobic oxidation of Fe2+, which is the product of ferric reductase activity. At saturating concentrations of Fe3+ chelates, ferric reductase activity is much greater than the iron uptake rate, leading to rapid oxidation of Fe2+ and superoxide generation. Therefore, O2 consumption is not an integral part of the iron assimilation process.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 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".