Selective determination of mitochondrial chelatable iron in viable cells with a new fluorescent sensor
Why this work is in the frame
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Bibliographic record
Abstract
Mitochondrial chelatable ("redox-active") iron is considered to contribute to several human diseases, but has not yet been characterized in viable cells. In order to determine this iron pool, we synthesized a new fluorescent indicator, rhodamine B-[(1,10-phenanthrolin-5-yl)aminocarbonyl]benzyl ester (RPA). In a cell-free system, RPA fluorescence was strongly and stoichiometrically quenched by Fe(2+). RPA selectively accumulated in the mitochondria of cultured rat hepatocytes. The intramitochondrial RPA fluorescence was quenched when iron was added to the cells in a membrane-permeant form. It increased when the mitochondrial chelatable iron available to the probe was experimentally decreased by the membrane-permeant transition metal chelators pyridoxal isonicotinoyl hydrazone and 1,10-phenanthroline. The concentration of mitochondrial chelatable iron in cultured rat hepatocytes, quantified from the increase in RPA fluorescence after addition of pyridoxal isonicotinoyl hydrazone, was found to be 12.2 +/- 4.9 microM. Inhibition of haem synthesis with succinylacetone did not alter the signal obtained in hepatocytes, but a rapid increase in the concentration of mitochondrial chelatable iron was observed in human erythroleukaemia K562 cells. In conclusion, RPA enables the selective determination of the highly physiologically and pathophysiologically interesting mitochondrial pool of chelatable iron in intact cells and to record the time course of alterations of this pool.
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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 it