Evidence for a physical component to the radiation-induced bystander effect?

Abstract

Purpose: The nature of the transferrable factor which goes from irradiated objects to bystander objects remains undefined. Most agree that a chemical entity is the likely ‘factor’ although some authors have produced in vitro evidence for the involvement of a physical component or a very potent volatile capable of traveling through air distances. In this paper we test the hypothesis that the communicated signal may be physical at least in part.

Methods: The in vivo fish model was used to allow signal production and response to occur in organisms in vivo without any shared blood or central nervous system (CNS) connections. A reporter assay and calcium flux measurements were used to detect signal production when irradiated fish were separated from unirradiated fish by (a) a plastic container, and (b) a foil-wrapped plastic container.

Results: The unirradiated fish showed bystander effects in both cases. The use of foil excludes the possibility of a light signal and although a highly active volatile could travel from one tank to another, the arrangement of sham and irradiated tanks makes it highly unlikely that this could explain our result.

Conclusion: We conclude that there must be a physical component in the mechanism such as a weak acoustic or electromagnetic signal.

Keywords::

• bystander effect
• low radiation dose
• Physical bystander signal
• fish radiobiology
• zebrafish

Acknowledgements

We acknowledge financial support from the National Sciences and Engineering Research Council (NSERC) Discovery Grants Programme, The Canada Research Chairs Programme, NSERC Industrial research Chairs Programme, The Canadian Nuclear Safety Commission (CNSC), CANDU Owner's Group (COG), AREVA Canada Ltd and Cameco Ltd.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.