1 Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo, 113-0032, Japan.
2 Instituto de Biologı´a Molecular y Celular del Ca´ncer (CSICUSAL), 37007, Salamanca, Spain.
3 Center for Animal Resources and Development, Kumamoto University, 2-2-1 Honjo, Kumamoto, 860-0811, Japan.
4 Laboratory for Chromosome Segregation, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
5 Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo, 113-0032, Japan. ywatanab@iam.u-tokyo.ac.jp.