Alpha-particle-induced bystander effects between zebrafish embryos in vivo

Dechorionaed embryos of the zebrafish, Danio rerio, at 1.5 h post-fertilization (hpf) were irradiated with alpha particles from an 241Am source. Thin polyallyldiglycol carbonate (PADC) films with a thickness of 16 μm were used as support substrates for holding the embryos and recorded alpha-particle hit positions, and thus enabled calculation of the dose absorbed by the embryos. The irradiated embryos were subsequently incubated with naïve (unirradiated) embryos in such a way that the irradiated and naïve embryos were spatially separated but the medium was shared. Acridine orange was used to perform in vital staining to show cell deaths in the naive embryos at 24 hpf. Our results gave evidence in supporting the existence of alpha-particle-induced bystander effects between zebrafish embryos in vivo, and a general positive correlation between the cell death signals in the naive embryos and the alpha-particle dose absorbed by the irradiated embryos.