The Radiation Induced Bystander Effect: Is there Relevance for Aquaculture? - Abstract
The radiation induced bystander effect describes the response of non-irradiated cells to transmissible signals emitted from irradiated cells. This has been shown in vivo in more than one species of irradiated fish swimming with non-irradiated bystander fish. Irradiation of adult fish results in a short-term bystander effect which then attenuates. However early life stage irradiation results in long term bystander effect induction, by the adults grown from irradiated eggs and larvae. This extends to a transgenerational effect, with the F1 and F2 generations of the irradiated fish being able to induce a bystander effect. Bystander effect induction also occurs between different fish species and between trophic levels. Proteomic analysis has revealed that direct irradiation results in proteomic changes that are indicative of tumorigenesis, whereas bystander effect proteomic changes suggest a protective or restorative response. The proteomic changes caused by the bystander effect also suggest that reactive oxygen species may be a component of the bystander signal. However experiments using a solid partition, between the irradiated and bystander fish, have demonstrated a physical component as well. The bystander effect is modulated by serotonin which suggests social rank may determine bystander effect induction. Overall the findings summarised in this review suggest that there may be relevance for the bystander effect in aquaculture which we propose now requires experimental attention.