Physiological and molecular responses of the chorioallantoic membranes to diluted bitumen exposures in multiple bird species
Bibliographic record
Abstract
Embryotoxicity is a well-known consequence of polycyclic aromatic compound (PAC) exposure, but the molecular mechanisms of action of PAC mixtures, especially for unconventional crude petroleum types such as diluted bitumen (dilbit), remain to be fully elucidated in birds. To explore the mechanism of action of PAC in birds, the egg-injection model was used. Eggs of domestic chicken (Gallus gallus), double-crested cormorant (Nannopterum auritum), and northern gannet (Morus bassanus) were injected with 0.5 μL/g of average species-specific egg weight of 1:10-1:10,000 dilutions of Clearwater or Cold Lake Blend dilbits into the air cell on embryonic Day 0 and were artificially incubated until the liver was formed. The injections of <0.16-335 ng total PAC/g egg were consistent with PAC concentrations measured in wild bird eggs and in embryos exposed to dilbit through eggshell oiling. Mortality and frequency of malformations were low across treatments. The expression of genes involved in xenobiotic detoxification in both liver and chorioallantoic membrane (CAM) differed among species in response to dilbit exposure. Cytochrome P450 1a (cyp1a) in the CAM of dilbit-exposed chickens was induced to a higher fold-change at a lower PAC concentration than the liver, but this pattern was not consistent in wild birds. The expression of additional genes involved in the aryl hydrocarbon receptor activation adverse outcome pathway were variable in the double-crested cormorant and northern gannet CAMs. Our study demonstrates the usefulness of CAM as a target tissue for PAC metabolism in embryotoxicity. Future studies should address the differential CAM physiology across bird species to better understand the variation of species responses to contaminants and consider the use of CAM in addition to liver.
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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".