Bibliographic record
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), an environmental toxicant, elicits a spectrum of deleterious biological responses including carcinogenesis. We hypothesize that TCDD exposure exerts its carcinogenicity, in part, by affecting the repair of DNA double strand breaks (DSBs) through homologous recombination (HR), mediated by the AhR signaling pathway. To investigate this hypothesis we used a Chinese hamster ovary (CHO) cell line (CHO 33) containing a neo direct repeat recombination reporter substrate to determine whether TCDD affects DNA DSB repair. The Saccharomyces cerevisiae mitochondrial endonuclease I-SceI was used to induce a site specific DSB within the upstream neo recombination substrate in the CHO 33 cells. The cells were then exposed to 500 pM of TCDD in the presence or absence of the AhR antagonist alpha-naphthoflavone (0.1 microM) for 24 h. Two weeks later HR frequencies were determined by counting the number of functional neo expressing, G418-resistant colonies per live cells plated. TCDD significantly increased HR frequency, demonstrating that it does in fact modulate the repair of DNA DSBs. Southern blot analysis of G418-resistant colonies using a cDNA neo probe determined that both gene conversion and gene deletion HR events occurred as a result of DNA DSB repair and TCDD exposure. Exposure of cells to alpha-naphthoflavone resulted in a significant decrease in TCDD-induced HR frequency. These results demonstrate that TCDD, potentially acting via the AhR, can modulate HR repair of DNA DSBs in CHO 33 cells.
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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) | 0.002 | 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".