Three-dimensional analysis and ultrastructural design of mitotic spindles from the cdc20 mutant of Saccharomyces cerevisiae

Eileen T. O'Toole, David N. Mastronarde, Thomas H. Giddings, Mark Winey, Daniel J. Burke, J. Richard McIntosh

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44 Scopus citations


The three-dimensional organization of mitotic microtubules in a mutant strain of Saccharomyces cerevisiae has been studied by computer-assisted serial reconstruction. At the nonpermissive temperature, cdc20 cells arrested with a spindle length of ~2.5 μm. These spindles contained a mean of 81 microtubules (range, 56-100) compared with 23 in wild-type spindles of comparable length. This increase in spindle microtubule number resulted in a total polymer length up to four times that of wild-type spindles. The spindle pole bodies in the cdc20 cells were ~2.3 times the size of wild-type, thereby accommodating the abnormally large number of spindle microtubules. The cdc20 spindles contained a large number of interpolar microtubules organized in a 'core bundle.' A neighbor density analysis of this bundle at the spindle midzone showed a preferred spacing of ~35 nm center-to-center between microtubules of opposite polarity. Although this is evidence of specific interaction between antiparallel microtubules, mutant spindles were less ordered than the spindle of wild-type cells. The number of noncore microtubules was significantly higher than that reported for wild-type, and these microtubules did not display a characteristic metaphase configuration. cdc20 spindles showed significantly more cross-bridges between spindle microtubules than were seen in the wild type. The cross-bridge density was highest between antiparallel microtubules. These data suggest that spindle microtubules are stabilized in cdc20 cells and that the CDC20 gene product may be involved in cell cycle processes that promote spindle microtubule disassembly.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalMolecular Biology of the Cell
Issue number1
StatePublished - Jan 1 1997
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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