Exposure to 3,3′,4,4′,5-pentachlorobiphenyl during embryonic development has a minimal effect on the cytochrome P4501A response to 2,3,7,8-tetrachlorodibenzo-<i>P</i>-dioxin in cultured chicken embryo hepatocytes
Bibliographic record
Abstract
Concentrations of dioxin-like compounds in avian eggs can vary substantially between individuals, species, and collection sites. Although the inducibility of cytochrome P4501A (CYPIA) in hepatocyte cultures is commonly used to predict species sensitivity to environmental contaminants, it is not known how exposure to dioxin-like compounds during embryonic development might alter this biomarker response. To investigate this question, we injected vehicle or 0.4, 0.8, or 1.6 microg/kg of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) into the air cell of fertilized chicken eggs before incubation, and we measured CYP1A endpoints in cultured hepatocytes of day-19 embryos from each treatment group. The CYP1A response to PCB 126 also was assessed in whole liver tissue. Embryonic exposure to the most environmentally relevant treatment, 0.4 microg/kg of PCB 126, increased CYPIA4 mRNA expression 29-fold compared to control values in whole liver tissue but only twofold compared to control values in cultured hepatocytes. The CYPIA response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was not altered in hepatocytes cultured from embryos treated with 0.4 microg/kg of PCB 126, but at 0.8 and 1.6 microg/kg of PCB 126, several concentration-dependent effects were observed. For example, embryos exposed to higher concentrations of PCB 126 in ovo were more responsive to CYP1A mRNA induction by TCDD in vitro. These findings suggest that exposure to environmental levels of dioxin-like compounds during incubation is not likely to alter species-sensitivity estimates derived from in vitro CYP1A data.
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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".