1. Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
2. Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
3. Chromosome Dynamics Laboratory, RIKEN, Wako 351-0198, Japan
4. Department of Physics, University of California, Berkeley, CA 94720
5. Department of Chemistry, University of California, Berkeley, CA 94720
6. HHMI, University of California, Berkeley, CA 94720