Caffeine inhibition of cytokinesis: Dynamics of cell plate formation-deformationin vivo

Summary The effect of caffeine on cell plate formation inTradescantia stamen hair cells has been studiedin vivo using Nomarski differential interference contrast microscopy. It is well known that caffeine is a potent inhibitor of cell plate formation. Direct examination of drug-treated cells reveals that the cell plate always arises and grows centrifugally until almost complete. Up to this point drug-treated cells are indistinguishable from controls. However in the presence of caffeine the plate never reaches completion but rather appears to melt away until no refractile structure remains. Even after cells have been cultured for 24 hours in caffeine a cell plate always arises only to subsequently break down. Studies on the time of caffeine action show that within minutes before the onset of cell plate formation, the drug efficiently reaches the target site. This effect is partially reversible by washing out the caffeine with HEPES/KCl buffer, however the time required for the cell plate to reach completion is prolonged and in some instances the plate appears to be fragmented. Adenosine is also partially effective in reversing the caffeine inhibition of cell plate formation.