1. Laboratory of Theriogenology and Animal Breeding Graduate School of Agricultural and Life Science The University of Tokyo Tokyo 113‐8657 Japan
2. Biomedical Informatics Laboratory Department of Molecular Life Science Tokai University School of Medicine Isehara Kanagawa 259‐1193 Japan
3. Laboratory of Signal Transduction Department of Cell Biology Institute for Virus Research Kyoto University Kyoto 606‐8507 Japan