1. Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan
2. National Institute for Environmental Studies, Japan, Center for Environmental Biology and Ecosystem Studies, Ibaraki 305-8506, Japan
3. Wildlife Genome Collaborative Research Group, National Institute for Environmental Studies, Ibaraki 305-8506, Japan
4. Department of Obstetrics and Gynecology, Juntendo University, Tokyo 113-8421, Japan
5. Division of Carcinogenesis and Cancer Prevention, National Cancer Center Research Institute, Tokyo 104-0045, Japan
6. Laboratory of Animal Reproduction, Department of Agriculture, Kindai University, Nara 3327-204, Japan
7. United Graduate School of Agricultural Sciences, Iwate University, Morioka 020-8551, Japan