Department of Molecular Biology, Faculty of Science, Saitama University, 255 Shimo-Ohkubo, Saitama, 338-8570 Japan. naokisat@molbiol.saitama-u.ac.jp|Department of Molecular Biology, Faculty of Science, Saitama University, 255 Shimo-Ohkubo, Saitama, 338-8570 Japan. naokisat@molbiol.saitama-u.ac.jp