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SUMMARY:Fission yeast interphase microtubules: self-sufficient and self-ce
 ntred! - Rafael Edgardo Carazo Salas\, CCL Cancer Research UK\, London
DTSTART:20060224T141500Z
DTEND:20060224T151500Z
UID:TALK4722@talks.cam.ac.uk
CONTACT:Duncan Simpson
DESCRIPTION:The generation of specialized patterns of microtubule polymers
  is essential for the correct growth and division of all eukaryotic cells\
 , from neurons to fungi. Fission yeast (Schizosaccharomyces pombe) cells\,
  for example\, grow only from their tips in a way that depends upon a unif
 orm organization (polarization) of their microtubules. \nUsing quantitativ
 e live-cell microscopy and permeabilized cell approaches\, we have been ab
 le to demonstrate that uniform microtubule organization in fission yeast c
 ells during growth (interphase) requires microtubule-associated motor acti
 vities. In these cells\, microtubules are organized in three or four bundl
 es and are uniformly polarized within the bundles.  This uniform polarizat
 ion was thought to be imposed by their de novo formation (nucleation) stri
 ctly around the surface of cell nuclei\, at the cells centres. Our work de
 monstrates that microtubules are actually nucleated everywhere in these ce
 lls and that their uniform polarization emerges instead from the transport
  of newly formed microtubules toward the cell centre along pre-existing mi
 crotubule bundles. Transport is mediated by the motor protein Klp2\, a mem
 ber of the evolutionarily conserved Kar3/Ncd family of kinesin motors. Fur
 thermore\, we show that cell nuclei are dispensable for microtubule patter
 n formation in those cells and that\, instead\, the patterns self-organize
  dynamically via association of microtubules with interacting factors\, su
 ch as motors. In this manner\, we find that motor-mediated self-organizati
 on secures the correct steady-state pattern of microtubules in spite of qu
 antifiable variation in microtubule content within and between cells. \nSe
 lf-organization processes were so far thought to be important for generati
 ng spatial order only in higher eukaryotic cells\, during cell division. O
 ur work using fission yeast cells strongly suggests that exploiting such p
 rocesses to create robust yet adaptable positional information may instead
  be widespread among many eukaryotic cell types. \n\nhttp://science.cancer
 researchuk.org/research/loc/london/lifch/nursep/nursepproj?version=4\n\n
LOCATION:IRC in Superconductivity Seminar Room\, Cavendish Laboratory
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