[1] Kobe Univ, Grad Sch Sci, Kobe, Hyogo 657, Japan
[2] Tokyo Gakugei Univ, Tokyo, Japan
[3] Kyoto Prefectural Univ, Grad Sch Agr, Kyoto 606, Japan
[4] RIKEN, GSC, Wako, Saitama 35101, Japan
[5] Okayama Univ, Fac Agr, Okayama 700, Japan
[6] RIKEN, BRC, Wako, Saitama 35101, Japan