Neutrons do not produce a bystander effect in zebrafish irradiated in vivo
Bibliographic record
Abstract
PURPOSE: Neutron irradiations at the McMaster Tandetron Accelerator were performed to study direct and bystander effects of neutrons in a live organism. METHODS: The neutrons were produced through (7)Li(p,n)(7)Be reaction. Although the gamma contamination of the neutron beam cannot be completely eliminated, it was designed to be as low as possible and remain below a threshold already established for bystander effects. Microdosimetric methods using a tissue-equivalent proportional counter have been used to measure the neutron and gamma doses for the cell irradiation. Previous data for a cell line exposed in vitro suggested that neutrons did not produce bystander effects at doses below 300 mGy. The current experiments sought to confirm this using a live whole organism (zebrafish) where tissue samples harvested 2 h after exposure were examined for direct evidence of apoptosis and tested for secretion of bystander factors using an established bioassay. Fish were either exposed directly to the beam or were allowed to swim with or in water previously occupied by irradiated fish. RESULTS: Using the zebrafish model it was found that there was significant direct cell death seen both by apoptosis scores and clonogenic assay when the neutron dose was approximately 100 mGy. An equivalent dose of gamma rays produced a more toxic effect. It was further found that neutrons did not induce a bystander effect in fish receiving signals from irradiated fish. CONCLUSION: The results confirm in vitro experiments which suggest neutrons do not induce bystander signaling. In fact they may suppress gamma induced signaling suggesting a possible intriguing new and as yet unclear mechanism.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".