Testing Predictions of the Double-Strand Break Repair Model Relating to Crossing Over in Mammalian Cells
Bibliographic record
Abstract
In yeast, four-stranded, biparental "joint molecules" containing a pair of Holliday junctions are demonstrated intermediates in the repair of meiotic double-strand breaks (DSBs). Genetic and physical evidence suggests that when joint molecules are resolved by the cutting of each of the two Holliday junctions, crossover products result at least most of the time. The double-strand break repair (DSBR) model is currently accepted as a paradigm for acts of DSB repair that lead to crossing over. In this study, a well-defined mammalian gene-targeting assay was used to test predictions that the DSBR model makes about the frequency and position of hDNA in recombinants generated by crossing over. The DSBR model predicts that hDNA will frequently form on opposite sides of the DSB in the two homologous sequences undergoing recombination [half conversion (HC); 5:3, 5:3 segregation]. By examining the segregation patterns of poorly repairable small palindrome genetic markers, we show that this configuration of hDNA is rare. Instead, in a large number of recombinants, full conversion (FC) events in the direction of the unbroken chromosomal sequence (6:2 segregation) were observed on one side of the DSB. A conspicuous fraction of the unidirectional FC events was associated with normal 4:4 marker segregation on the other side of the DSB. In addition, a large number of recombinants displayed evidence of hDNA formation. In several, hDNA was symmetrical on one side of the DSB, suggesting that the two homologous regions undergoing recombination swapped single strands of the same polarity. These data are considered within the context of modified versions of the DSBR model.
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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".