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 Végétables (CERMAV, ICMG-CNRS; affiliated with Université Joseph Fourier), BP 53, F38041 Grenoble Cedex 9, France