1. Department of Cell Science; Faculty of Graduate School of Science and Technology; Niigata University; Nishi-ku Niigata 950-2181 Japan
2. Institute for Environmental Sciences; 1-7 Ienomae Obuchi Rokkasho-mura Kamikita-gun Aomori 039-3212 Japan
3. School of Life Science and Technology; State Key Laboratory of Urban Water Resource and Environment; Harbin Institute of Technology; Harbin 150001 China