A rapid assay for mitochondrial DNA damage and respiratory chain inhibition in the yeast <i>Saccharomyces cerevisiae</i>
Bibliographic record
Abstract
There is a need for a rapid assay to identify agents that damage mitochondria because the mitochondrion may be an important target for numerous environmental mitotoxins. Certainly at least one chemotherapeutic regimen (CHOP therapy) that includes doxorubicin can induce cardiomyopathy through mitochondrial genotoxicity in cardiac muscle cells. Yeast cells (1.5 x 10(6)-10(7)) in water are spread on a YEPD plate, and, when the suspension of cells has dried, a small well (12 mm diameter) is cut into the agar; 200-400 microl of a solution of the presumptive mitochondrial genotoxin is placed in the well, and the plates are incubated for 2 days. The genotoxin forms a concentration gradient through the agar and affects the growing cells. An overlay containing tetrazolium chloride is added, and the plates are incubated for 6-24 hr. Respiring cells turn red, and nonrespiring cells, with damaged DNA or inhibited respiratory chains, that are adjacent to the well, are white. A white ring, or a more lightly colored red ring, around the well indicates the presence of cells with lowered respiratory activity which may be fully reversible when the mitochondrial genotoxin is removed. In preliminary experiments, doxorubicin (= adriamycin) shows strong activity with this assay; cyclophosphamide is negative, and 4-hydroxycyclophosphamide, a metabolite of cyclophosphamide, is weakly positive. Ethidium bromide, methotrexate, 5-fluorouracil, and 5-fluorocytosine also are mitochondrial genotoxins. Antifungal agents similar to 5-fluorocytosine and anthelmintic compounds such as pyrvinium iodide can be powerful mitochondrial genotoxins.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".