Fluorescent speckle microscopy (FSM) of poleward tubulin movement (flux) in a control Xenopus laevis egg extract spindle

(Left) Individual tubulin speckles undergoing antiparallel poleward movement. (Right) Trajectories of individual speckles are recovered by software for quantitative analysis. Red and green squares mark speckles moving to the left and the right poles, respectively. In each frame, the center of each square denotes the current position of the corresponding speckle being followed. Only those speckles whose trajectories last at least four frames are displayed using squares. Frame rate: 5 sec/frame. Display rate: 15 frames/sec. Field of view: width × height, 83 × 66 μm. [ Supplemental movie from Imaging: A Laboratory Manual, Cold Spring Harbor Laboratory Press.]