Authors: José M SeguíSimarro L Andrew Staehelin
Publish Date: 2005/09/03
Volume: 223, Issue: 2, Pages: 223-236
Abstract
Cytokinesis in plants involves both the formation of a new wall and the partitioning of organelles between the daughter cells To characterize the cellular changes that accompany the latter process we have quantitatively analyzed the cell cycledependent changes in cell architecture of shoot apical meristem cells of Arabidopsis thaliana For this analysis the cells were preserved by highpressure freezing and freezesubstitution techniques and their Golgi stacks multivesicular bodies vacuoles and clathrincoated vesicles CCVs characterized by means of serial thin section reconstructions stereology and electron tomography techniques Interphase cells possess ∼35 Golgi stacks and this number doubles during G2 immediately prior to mitosis At the onset of cytokinesis the stacks concentrate around the periphery of the growing cell plate but do not orient towards the cell plate Interphase cells contain ∼18 multivesicular bodies most of which are located close to a Golgi stack During late cytokinesis the appearance of a second group of cell plateassociated multivesicular bodies coincides with the onset of CCV formation at the cell plate During this period a 4× increase in CCVs is paralleled by a doubling in number and a 4× increase in multivesicular bodies volume The vacuole system also undergoes major changes in organization size and volume with the most notable change seen during early telophase cytokinesis In particular the vacuoles form sausagelike tubular compartments with a 50 reduced surface area and an 80 reduced volume compared to prometaphase cells We postulate that this transient reduction in vacuole volume during early telophase provides a means for increasing the volume of the cytosol to accommodate the forming phragmoplast microtubule array and associated cell plateforming structuresWe thank Mr Ricardo Mantilla CIRES University of Colorado Boulder CO USA and Prof Jaime RenauPiqueras Centro de Ïnvestigación Hospital “La Fe” Valencia Spain for their mathematical advice and Mrs Erin White MCDB University of Colorado Boulder CO USA for her valuable help Many thanks are also due to David Mastronarde and the rest of members of the Boulder Laboratory for 3Dimensional Electron Microscopy of Cells MCDB University of Colorado Boulder CO USA Grant RR00592 This work was supported by National Institute of Health Grant GM 61306 to LAS
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