1. Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan, Centre de Recherches sur les Macromolécules Végétales (Affiliated with Joseph Fourier University of Grenoble), C.N.R.S. B.P. 53, 38401, Grenoble Cedex 9, France, and Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto 611-0011, Japan