Effects of accelerated carbon-ion on the induction of dominant lethality in the teleost fish, Oryzias latipes

About a small teleost fish, Oryzias latipes, it has been reported that the dominant lethal mutation test by using the hatchability of eggs is useful for the estimation of the mutagenic effects of radiations and chemicals. In the present experiment, the genetic effects of heavy ions on the male germ cells of the fish by using the dominant lethal test system were studied. One of the albino strain of Medaka was used. The hatchability of fertilized eggs was examined to determine the no irradiation control value. The male of each pair was irradiated with the carbon ions accelerated with the RIKEN ring cyclotron. In the no irradiation control, most embryos hatched 7 - 10 days after fertilization. The numbers of dead embryos and newly hatched fry were counted every day in each cluster. Relative hatchability rate (RHR) was calculated. Dominant lethal rate was calculated as (1-RHR). The number of the irradiated fish pairs and the number of the examined eggs, the fertility of eggs and the hatchability of fertilized eggs due to irradiation, and the dominant lethal rate are reported. The induction of dominant lethality was about two times as high in carbon beam as that by X-ray. (K.I.)