1. Department of Biology, Kobe University, Kobe 657-8501, Japan
2. Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan
3. Japan Science and Technology Agency, Precursory Research for Embryonic Science and Technology, Kawaguchi 332-0012, Japan
4. Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
5. Department of Physiological Sciences, The Graduate University for Advanced Studies, Hayama 240-0193, Japan