1. Department of Bioresources Chemistry, Chiba University, 648 Matsudo, Matsudo-shi, Chiba 271-8510, Japan, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan, and National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan