1. Department of Anthropology, Faculty of Science; The University of Tokyo; Hongo Bunkyo-ku Tokyo 113
2. Department of Cytogenetics, Medical Research Institute; Tokyo Medical and Dental University; Yushima Bunkyo-ku Tokyo 113
3. Jigokudani-Yaen Park; Yamanouchi Shimotakai-gun, Nagano 380-04
4. Institute for Virus Research; Kyoto University; Kawara-cho Sakyo-ku Kyoto, Kyoto 606