1. Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
2. Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
3. Laboratory of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Kobe, Hyogo 658-0003, Japan
4. Department of Developmental Biology and Neuroscience, Graduate School of Life Science, Tohoku University, Sendai, Miyagi 980-8577, Japan