Physical Aspects of Spindle Assembly

Abstract

The spindle is a complex assembly of microtubules, motors, and other associated proteins, which segregate chromosomes during cell division.In metaphase, the spindle exists in a steady-state with a constant flux of molecules and energy continuously modifying and maintaining its architecture. While the self-organization of systems of microtubules and motors have been investigated using theory and experiments, there have been few attempts to test if the proposed theories can be used to understand the dynamics and structure of complex biological systems in vivo. Here we use polarized light microscopy, 3D time-lapse spinning disk confocal microscopy, single molecule imaging, second harmonic generation microscopy, and mechanical measurements to test the validity of continuum models of metaphase spindles. Our results show that a simple continuum model can quantitatively explain spindle structure and dynamics, demonstrate that rigorous physical theories can be used to quantitatively describe complex subcellular systems, and provides a framework for understanding the structure of the spindle and its response to physical and molecular perturbations.