1. Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan
2. Division of Bio–resources, Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan
3. Present address: Center of Biomedical Research, Research Center for Human Disease Modeling, Graduate School of Medical Sciences, University of Kyushu, 3-1-1 Maidashi, Fukuoka, Fukuoka 812-8582, Japan
4. Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-Nishi, Miyazaki, Miyazaki 889-2192, Japan