1. Biology Department, St. Olaf College, Northfield, Minnesota, USA
2. Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, USA
3. The Boulder Laboratory for 3D Electron Microscopy of Cells, Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, USA
4. Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
5. Biology Department, Millsaps College, Jackson, Mississippi, USA