1. Laboratory of Animal Resources, Faculty of Bioindustry, Tokyo University of Agriculture, 196, Aza-Yasaka, Abashiri-shi, 099-2422, Japan
2. Toa Medical Electronics CO., LTD, 4-4-4 Takatsukadai Nishi-ku, Kobe 651-2271, Japan
3. Laboratory of Animal Genetics and Breeding, Faculty of Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan