Radiation resistance and its inheritance in the silkworm, Bombyx mori

Exposure to radiation causes various biological effects, which can be detected both in the exposed animals and their offspring. In the silkworm, Bombyx mori, many studies in somatic and genetic effects of radiation have been conducted using various doses and qualities of radiation sources, because of their usability for mutation induction. However, differences in sensitivity to radiation among silkworm strains remain unknown. In the present study, we have identified two resistant strains (p50 and m042) and two sensitive strains (Crossed D sign2 and m91) for γ-irradiation by screening genetic stocks of B. mori maintained in Kyushu University Graduate School. In reciprocal mating experiments, there is liability that F₁ progeny became more sensitive to γ-irradiation when the susceptible strains were used as the female parent. Even though details remain to be determined, it appears from the current studies that radiation sensitivity in the silkworm is controlled, at least in part, by maternal cytoplasmic inheritance.