8. Does Oxidative Stress Function as a Biomarker of Environmental Mercury Contamination in Double-Crested Cormorant?
Bibliographic record
Abstract
Mercury is a widespread contaminant that has been shown to induce a wide range of adverse health effects in several animal species including changes in gene expression. This study was undertaken to explore the relationship between environmental mercury exposure and oxidative stress induction in the blood of double-crested cormorants (Phalacrocorax auritus). Blood was sampled at five sites across Central and Southern Ontario ranging from low to high risk of mercury contamination and was analyzed for total mercury concentration. To assess cellular oxidative stress, the expression of glutathione peroxidases 1 and 3, glutathione S-transferase µ3, superoxide dismutase 1 and heat-shock protein 70 kd-8 were measured in whole blood samples. Preliminary results indicate that erythrocyte mercury concentrations ranged from 5.0 to 27.3 µg/g dry weight. Mean (± standard error) site-specific erythrocyte mercury concentrations ranged from 9.0 ± 3.6 µg/g dry weight in Lake Erie to 17.5 ± 4.2 µg/g dry weight in Lake Nipissing. Approximately 27% of the birds exceeded the threshold concentration for adverse effects in another piscivorous bird, the common loon (Gavia immer). Results of gene expression analysis will be discussed in relation to mercury concentration. Our study will help to develop an understanding of the interactions of environmental mercury exposure and oxidative stress-related gene expression and will contribute to the development of sub lethal biomarkers for mercury toxicity in wild aquatic piscivorous birds.
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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) | 0.001 | 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".