Three-dimensional ultrastructure of Saccharomyces cerevisiae meiotic spindles

Mark Winey, Garry P. Morgan, Paul D. Straight, Thomas H. Giddings, David N. Mastronarde

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Meiotic chromosome segregation leads to the production of haploid germ cells. During meiosis I (MI), the paired homologous chromosomes are separated. Meiosis II (MII) segregation leads to the separation of paired sister chromatids. In the budding yeast Saccharomyces cerevisiae, both of these divisions take place in a single nucleus, giving rise to the four-spored ascus. We have modeled the microtubules in 20 MI and 15 MII spindles by using reconstruction from electron micrographs of serially sectioned meiotic cells. Meiotic spindles contain more microtubules than their mitotic counterparts, with the highest number in MI spindles. It is possible to differentiate between MI versus MII spindles based on microtubule numbers and organization. Similar to mitotic spindles, kinetochores in either MI or MII are attached by a single microtubule. The models indicate that the kinetochores of paired homologous chromosomes in MI or sister chromatids in MII are separated at metaphase, similar to mitotic cells. Examination of both MI and MII spindles reveals that anaphase A likely occurs in addition to anaphase B and that these movements are concurrent. This analysis offers a structural basis for considering meiotic segregation in yeast and for the analysis of mutants defective in this process.

Original languageEnglish (US)
Pages (from-to)1178-1188
Number of pages11
JournalMolecular Biology of the Cell
Issue number3
StatePublished - Mar 1 2005
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology
  • Genetics
  • Molecular Biology


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