Development and characterization of a stable epithelial cell line from Muta™Mouse lung
Bibliographic record
Abstract
We have isolated and characterized a stable epithelial cell line from Muta Mouse lung that is a suitable complement to the in vivo assay system. The cells are contact inhibited, forming a flat monolayer, and retain several epithelial/pulmonary characteristics. The genome is stable across more than 50 generations, with a modal chromosome number of 78. Spontaneous rates of micronuclei (19.2 +/- 1.4 per 1,000), sister chromatid exchanges (0.25 +/- 0.004 per chromosome), and chromosome aberrations ( approximately 4%) are lower than, or comparable to, other transgenic cell lines currently used in mutagenicity research. Fluorescence in situ hybridization analyses showed that 80% of cells contain three lambdagt10lacZ loci. Slot-blot analyses indicated that the average cell contains approximately 17 transgene monomers. Spontaneous mutant frequency at the lacZ transgene is stable (39.8 +/- 1.1 x 10(-5)), and the direct-acting mutagens N-ethyl-N-nitrosourea and ICR-191 yielded increases in mutant frequency of 6.3- and 3.2-fold above control, respectively. Benzo[a]pyrene (BaP) exposure increased mutant frequency more than 25-fold above control and did not require an exogenous metabolic activation mixture. Inhibition of Cyp1A1 by 5 microM alpha-naphthoflavone eliminated BaP mutagenesis. Activation and mutation induction by the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine required a low concentration (0.05% v/v) of exogenous rat liver S9. High activity of alpha, micro, and pi glutathione-S-transferase isozymes appears to confer resistance to the cytotoxic effects of xenobiotics. The cell line is a suitable complement to the in vivo Muta Mouse assay, and provides an opportunity for routine in vitro mutagenicity testing using an endpoint that is identical to that employed in vivo.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.003 |
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".