Mechanisms of chromosome movement during cell division

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When chromosomes are not distributed equally into the two daughter cells during cell division, the resultant cells die or become abnormal, e.g., leading to birth defects or cancers. We study how chromosomes move to the two daughter cells. As chromosomes move to the two "poles" of the cell before the cell divides, a "spindle fibre" extending between each chromosome and the pole shortens without changing width. We can compare this to a boat connected by a rigid rope to a dock toward which it moves. The prevailing view is that a winch pulls the rope to the dock. We have shown, however, that other forces propel the boat: the boat continues to move normally to the dock after we sever the rope (by local irradiation), so external forces (from a "spindle matrix") must propel the boat to the dock - e.g., people might stand in the shallow water and pull the remnant rope to the dock, or currents in the water might propel the boat to the dock. We have used specific drugs to identify which (non-rope) components might produce forces; we will use local irradiations, drug treatments, and genetic tools to identify and study the forces that propel the rope and boat to the dock.