Photolytic Degradation Products of Two Highly Brominated Flame Retardants Cause Cytotoxicity and mRNA Expression Alterations in Chicken Embryonic Hepatocytes
Bibliographic record
Abstract
Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) and 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) are photolytically unstable flame retarding chemicals. Here, photocatalyzed byproducts of TeDB-DiPhOBz and BDE-209 (i.e Br(8)- to Br(11)-PB-DiPhOBz congeners from TeDB-DiPhOBz, and Br(6)- to Br(8)-BDE congeners from BDE-209), formed after 21 days of natural sunlight irradiation (SI), were assessed for exposure effects on cytotoxicity and mRNA expression levels of selected genes in chicken embryonic hepatocytes (CEH). CEHs were exposed for 36 h to concentrations of SI- and nonirradiated (NI)-TeDB-DiPhOBz and BDE-209. Cytotoxic effects were observed only in CEH exposed to 50 μM SI-BDE-209. Results from a custom-designed Avian ToxChip polymerase chain reaction array showed that NI-TeDB-DiPhOBz and NI-BDE-209, up to maximum concentrations of 1.9 and 9 μM, respectively, caused limited changes in mRNA levels of 27 genes from toxicologically relevant pathways, including phase I/II metabolism, the thyroid hormone pathway, lipid/cholesterol metabolism, oxidative stress, immune response, and cell death. In contrast, 12 and 14 of the 27 genes were altered after exposure to 25 μM SI-TeDB-DiPhOBz or 10 μM SI-BDE-209, respectively. Aryl hydrocarbon receptor (AhR)-related CYP1A4 mRNA levels were the most altered on the PCR array with an induction of 560- and 5200-fold after exposure to 1 or 25 μM SI-TeDB-DiPhOBz, respectively, and 2500- and 2300-fold after exposure to 1 or 10 μM SI-BDE-209, respectively. A dioxin-responsive luciferase reporter gene assay confirmed that the CYP1A4 inductions were independent of the dissolution solvents used (tetrahydrofuran/n-hexane, n-hexane, or methanol) during photolysis. Overall, degradation of TeDB-DiPhOBz and BDE-209 by natural sunlight generates byproducts that affect in vitro expression of genes, especially the AhR-mediated CYP1A4.
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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".