1. Graduate School of Life Science, University of Hyogo, Himeji 671-2201, Japan
2. Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
3. Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan
4. Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki 567-0047, Japan
5. National Institute for Physiological Sciences, Okazaki 444-8585, Japan
6. RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan
7. Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347