Pipping Success, Isomer-Specific Accumulation, and Hepatic mRNA Expression in Chicken Embryos Exposed to HBCD
Bibliographic record
Abstract
Hexabromocyclododecane (HBCD) is an additive flame retardant used primarily in polystyrene foams. HBCD is a persistent contaminant that has been detected in abiotic and biotic matrices, including wild avian species. The toxicological implications of exposure are not well characterized. We recently identified molecular end points responsive to HBCD exposure in chicken embryonic hepatocytes (CEHs) including genes involved in xenobiotic metabolism, thyroid hormone transport, and lipid metabolism. In the current study, a technical mixture of HBCD (HBCD-TM), comprising 12% alpha-, 11% beta-, and 77% gamma-stereoisomers, was injected into the air cell of chicken eggs prior to incubation. Embryonic viability to pipping, isomer-specific HBCD accumulation, and hepatic mRNA expression of the genes identified in the in vitro study were determined. Concentrations of 100 and 10,000 ng/g decreased pipping success while 50, 300, and 1000 ng/g had no effect. In contrast to HBCD-TM, the isomeric composition in liver tissue was significantly different for alpha- (31%) and gamma-HBCD (61%) demonstrating that isomer-specific processes were occurring in the egg and/or developing embryo. Exposure to 1000 ng/g HBCD-TM significantly upregulated cytochrome P450 (CYP) 2H1, CYP3A37, uridine 5'-diphospho-glucuronosyltransferase, and deiodinase 2, while liver fatty acid-binding protein and insulin-growth factor 1 expression were significantly decreased at 100 and 10,000 ng/g, respectively. The alterations in hepatic mRNA levels were in concordance with those observed in CEH highlighting the utility of both approaches for identifying molecular mechanisms of action. Research on the effects of HBCD in wild avian species is warranted.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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 teacher head, 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".