A novel <i>Escherichia coli</i>‐derived mutation detected with the Big Blue® <i>cII</i> mutant selectable assay
Bibliographic record
Abstract
Transgenic mouse mutation detection systems allow investigation of the origins and mechanisms of mutation associated with exogenous and endogenous mutagen exposures in individual tissues and cell types. In the past, selection assays for transgenic mutants have been contaminated with nonmurine-derived mutations and assay validation is critical to ensure murine in vivo origins of mutations. This is critical in studies of spontaneous mutations and extrapolation to endogenous mammalian genes. Herein, we provide one measure of the contribution of Escherichia coli (E. coli)-derived mutations to the Big Blue(R) cII transgene mutant selection assay. We report the first direct evidence of an E. coli-derived cII mutation identified among mutations recovered in the cII selective assay. An E. coli transposable 5 (Tn5) element IS50R inverted repeat (1,534 bp) was identified at base pair 414 in the cII transgene and the insertion generated a 9 bp target site duplication typical of this type of transposition. The bacterial transposition occurred only once in the assay of 25 x 10(6) plaque forming units and sequencing of 1,177 cII mutants. The observed frequency of this type of mutation is 4 x 10(-8) in retrieved lambda phage and 8.5 x 10(-4) in harvested cII mutants and thus a very rare occurrence in typical analyses of spontaneous in vivo mutations. Given that the frequency of transposition is equal to, or an order of magnitude higher, than the frequency of point mutations in E. coli, this article provides excellent validation for the murine origins of mutations detected using the cII mutant selection assay.
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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 | 0.000 | 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) | 0.000 | 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".