Effects of alpha particles on zebrafish embryos.

Dechorionated zebrafish embryos were irradiated at 1.5 h post fertilization (hpf) to low-doses of alpha particles, viz., 1.4, 2.8, 5.6, 11.2 mGy (determined using Monte Carlo simulations). At 24 hpf, these embryos were then examined for apoptotic cells through acridine orange staining. The mean number of apoptotic cells was found to decrease significantly from controls to 1.4-mGy irradiation, and then to increase almost linearly to 2.8, 5.6 and 11.2-mGy irradiation. This trend is a typical characteristic of a hormetic effect.