Integrated Assesment of Long-term Cosmic Radiation through Biological Responses of the Silkworm, Bombyx mori, in Space PI: Dr. Toshiharu FURUSAWA (Emeritus Prof., Kyoto Institute of Technology)

1. Objectives of Proposed Research The eggs of the silkworm (Bombyx mori) are used as an indicator for monitoring biological responses to long-term cosmic radiation. (1) Morphological responses during embryogenesis (2) Gene expression The correlation between cumulative dose of cosmic ray and functional alterations is assessed from the following biological responses; 1) 2)

3. Scientific Data is abundant in physiological and genetic fields Differentiation, Diapause, Metamorphosis and genetic characteristics The technique of egg preservation has been established Embryos can be maintained in diapause state for at least 2 years by controlling storage temperature of eggs. 1. Large quantities of silkworm eggs can be loaded onto the ISS Statistically significant data; survival ratio, mutations, abnormal morphogenesis Egg size ： 1.3 x 1.0 mm Merits of Silkworm Eggs as Biological Models 2. Flight Sample for Rad Silk (1) 1.26±0.05mm 0.98 ±0.04 mm 2. Experiment duration: More than 3 months

Embryonic Development of the Silkworm Diapause Diapause Termination When transferred to 25 ℃ Ｒｅｓｕｍｐｔｉｏｎ ｏｆ ｅｍｂｒｙｏｎｉｃ ｄｅｖｅｌｏｐｍｅｎｔ Blastokinesis Black-striped strain (P S ) Hatching 2. Flight Sample for Rad Silk (2) 5 ℃, about 3months Oviposition Embryo Pre-larva Embryo stops cell division to arrest embryonic development Embryos turn out their bodies toward the inside.

Result of previous Space Experiment (STS-84) 2. Flight Sample for Rad Silk (3)

P s /p Egg Radiation P S /P S x p/p (Black-striped) (Normal: white) Adult P S /p (Black-striped larvae with White spot) Larva The exposure of diapause eggs to X-rays or heavy ion particles induces somatic mutation appearing as white spot on the black integument 3. Results of Ground Experiment (1)

Dose (Gy) Somatic Mutation (%) Diapause-terminated eggs at 5 ℃ were transferred to 25 ℃ to resume embryogenesis, and then 2 days later exposed to the irradiation of Fe ions. The somatic mutation was induced even by the irradiation of 2mGy Fe ion beam to 2 day-old eggs after resumption of embryonic development 3. Results of Ground Experiment (2)