Exchange rates of cadmium between a burrowing mayfly and its surroundings in nature
Bibliographic record
Abstract
We conducted a reciprocal transfer of nymphs of the burrowing mayfly Hexagenia limbata between two rivers harboring populations of this insect that differed in their cadmium (Cd) concentrations. We measured Cd uptake and loss rates simultaneously in the field at several levels of biological organization: in the gut and body of whole nymphs as well as in three subcellular fractions. The most marked changes in Cd concentrations occurred in the insect's gut, where Cd was largely associated with heat-stable proteins, a fraction that includes the metal-binding protein metallothionein. Because most of the Cd that entered nymphs was detoxified in this manner, we would not expect it to have direct toxic effects; however, it would be readily transferred to higher trophic levels. Our data on subcellular partitioning suggest that there is a fast-exchanging pool of Cd bound to heat-stable proteins such as metallothionein and a slow-exchanging pool bound to either or both of the remaining fractions (heat-denatured proteins; remainder, which includes exoskeleton and granules). Nymphs of H. limbata responded rapidly to changes in bioavailable Cd, which suggests that they would be useful for monitoring changes in ambient Cd for weeks or months in the field. A one-compartment model successfully explained the changes we observed in nymph Cd values. Furthermore, values of the model constant for Cd loss were close to those reported for Hexagenia rigida in the laboratory, which suggests that accumulation patterns observed in the laboratory can be representative of those measured in nature.
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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 | 0.000 | 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 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".