1. Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
2. Zoologisch Institute, Ludwig-Maximilians Universitat, 80333 München, Germany
3. Central Research Laboratory, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
4. Department of Physiology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan