1. Central Research Laboratory, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji, Tokyo 185-8601, Japan
2. Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka-shi, Fukuoka 812-8581, Japan