Measuring the dynamics of molecular motors inside mitotic spindles

Cell division is a very dynamic process during which the internal architecture of higher cells is completely reorganized. A highly dynamic supra-molecular machine, the mitotic spindle, self-organizes around chromosomes and transports them to the two daugh ter cells. Several molecular motors play an essential role for spindle organization and function. These motors are mechano-chemical enzymes that transform chemical energy into mechanical work. However, how they function in a coordinated manner in the spin dle is not understood. The goal of this project is to measure the dynamics of the most important motors for spindle formation inside spindles of individual cells. Advanced fluorescence microscopy techniques will be used to monitor the real-time behavior o f motors on microtubules. Proof of principle will be established in Xenopus egg extracts. Final experiments will be performed in Xenopus cells. Knowing the binding /unbinding turnover, the speed and the local and temporal regulation of motor activities is essential to understand the regulated spindle dynamics and function during cell division.