1. Laboratory of Radiation Biology, Department of Applied Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan;
2. Laboratory of Toxicology, Department of Environmental Veterinary Science, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan;
3. Central Institute of Isotope Science, Hokkaido University, Sapporo, Japan;
4. Laboratory of Biophysics, School of Science and Technology, Meiji University, Kawasaki, Japan