Related Experiment Video
Updated: May 11, 2026
04:53
Zebrafish Larvae as a Model to Evaluate Potential Radiosensitizers or Protectors
Published on: August 25, 2022
Bystander effect between zebrafish embryos in vivo induced by high-dose X-rays
V W Y Choi1, C Y P Ng, A Kobayashi
1Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, Hong Kong.
Environmental Science & Technology
|May 15, 2013
Summary
High-dose X-ray irradiation of zebrafish embryos induces a bystander effect in nearby naive embryos. This effect, mediated by nitric oxide (NO), can be suppressed by NO scavengers, indicating NO
Area of Science:
- Radiation biology
- Developmental biology
- Cell signaling
Background:
- The in vivo bystander effect describes non-targeted cells responding to radiation-induced damage in neighboring cells.
- Zebrafish embryos are a valuable model for studying radiation effects due to their optical transparency and rapid development.
Purpose of the Study:
- To investigate the bystander effect in zebrafish embryos following X-ray irradiation.
- To elucidate the role of nitric oxide (NO) in mediating this radiation-induced bystander response.
Main Methods:
- Zebrafish embryos (Danio rerio) at 5 hours post fertilization (hpf) were irradiated with 4-Gy X-rays.
- Apoptotic signals in naive embryos were quantified using the TUNEL assay at 25 hpf.
- The effects of nitric oxide (NO) scavenger cPTIO and CO releaser CORM-3 were assessed.
- Irradiated embryo conditioned medium (IECM) was used to induce bystander effects.
Main Results:
- Irradiated zebrafish embryos released a signal inducing a bystander effect in naive embryos.
- The bystander effect was suppressed by the NO scavenger cPTIO, but not by CORM-3.
- A bystander effect was also induced by IECM, independent of direct cell-to-cell contact.
- This IECM-induced effect showed a threshold, being abolished by 2x dilution.
Conclusions:
- Nitric oxide (NO) plays a crucial role in the X-ray-induced bystander effect between zebrafish embryos.
- The bystander effect can be mediated through medium-borne signals, suggesting paracrine signaling.
- The response exhibits characteristics of a threshold phenomenon, implying a specific concentration of signaling molecules is required.
