1. Department of Molecular Cell Biology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita-shi, Osaka 565-0871,Japan
2. Laboratory of Cytogenetics, Division of Bioscience, Graduate School of Environmental Earth Science, Hokkaido University, North 10, West 8, Kita-ku,Sapporo 060-0810, Japan
3. Laboratory of Animal Cytogenetics, Center for Advanced Science and Technology,Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
4. Department of Laboratory Sciences for Animal Experimentation, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita-shi,Osaka 565-0871, Japan
5. Department of Cell Biology, Duke University Medical Center, PO Box 3709, DUMC,Durham, NC 27710, USA