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| Dynamics of Membrane Proteins during Cytokinesis |
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| Y.-l. Wang, J.D. Silverman and L.-g. Cao (1994) |
| J. Cell Biol. 127:963-971. |
| D.J. Fishkind, J.D. Silverman and Y.-l. Wang (1996) |
| J. Cell Sci. 109:2041-2051. |
| Many membrane proteins are linked to the underlying actin cortex. To follow the movement of the membrane-cortex during cytokinesis, we dropped fluorescent latex beads on the cell surface to label membrane proteins. Their movement during cell division was recorded by fluorescence imaging. |
| Movement of Surface Receptors during Normal Division |
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Size = 224 x 180 pixels.| After anaphase onset, surface bound beads start to move toward the equator. Many beads show a sudden surge in speed upon the passage of chromosomes. Are there signals emanating from the separating chromosomes that trigger the bead movement? |
| Effects of Cytochalasin on the Movement of Surface Receptors |
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Size = 272 x 236 pixels.| When cells are treated with cytochalasin D to disrupt actin filaments after the onset of bead movement, the beads change their pattern of movement and aggregate into clusters. Many of them reverse the direction and move away from the furrow, suggesting that contractile forces may be present throughout the cortex. |
| Effects of Nocodazole on the Movement of Surface Receptors |
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Size = 320 x 232 pixels.| When cells are treated with nocodazole to disassemble microtubules after the onset of bead movement, directional movement of beads stopped, suggesting that cortical movement requires microtubules. This example shows the most uniform behavior. In other cells we have sometimes seen a more variable response, which likely reflect the non-uniform susceptibility of interzonal microtubules to nocodazole as we found more recently. |
| Effects of Taxol on the Movement of Surface Receptors |
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Size = 240 x 236 pixels.| When cells are treated with taxol to induce microtubule reorganization after the onset of bead movement, the pattern of bead movement shows a striking fountain pattern. The converging paths toward the center of the cell appear to follow the distribution of the distal ends of microtubules. |