The influence of light on copper‐limited growth of an oceanic diatom,<i>Thalassiosira oceanica</i>(Coscinodiscophyceae)
Bibliographic record
Abstract
Thalassiosira oceanica ( CCMP 1005) was grown over a range of copper concentrations at saturating and subsaturating irradiance to test the hypothesis that Cu and light were interacting essential resources. Growth was a hyperbolic function of irradiance in Cu‐replete medium (263 fmol Cu′ · L −1 ) with maximum rates achieved at 200 μmol photons · m −2 · s −1 . Lowering the Cu concentration at this irradiance to 30.8 fmol Cu′ · L −1 decreased cellular Cu quota by 7‐fold and reduced growth rate by 50%. Copper‐deficient cells had significantly slower ( P < 0.0001) rates of maximum, relative photosynthetic electron transport ( rETR max ) than Cu‐sufficient cells, consistent with the role of Cu in photosynthesis in this diatom. In low‐Cu medium (30.8 fmol Cu′ · L −1 ), growth rate was best described as a positive, linear function of irradiance and reached the maximum value measured in Cu‐replete cells when irradiance increased to 400 μmol photons · m −2 · s −1 . Thus, at high light, low‐Cu concentration was no longer limiting to growth: Cu concentration and light interacted strongly to affect growth rate of T. oceanica ( P < 0.0001). Relative ETR max and Cu quota of cells grown at low Cu also increased at 400 μmol photons · m −2 · s −1 to levels measured in Cu‐replete cells. Steady‐state uptake rates of Cu‐deficient and sufficient cells were light‐dependent, suggesting that faster growth of T. oceanica under high light and low Cu was a result of light‐stimulated Cu uptake.
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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 | 0.001 | 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 | 0.001 | 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".