Related Experiment Video

Updated: Aug 20, 2026

Evaluation of the Spindle Assembly Checkpoint Integrity in Mouse Oocytes
10:09

Evaluation of the Spindle Assembly Checkpoint Integrity in Mouse Oocytes

Published on: September 13, 2022

The spindle assembly checkpoint is not essential for CSF arrest of mouse oocytes

Chizuko Tsurumi1, Steffen Hoffmann, Stephan Geley

  • 1Max-Planck-Institut fuer Immunbiologie, Developmental Biology, Freiburg, Germany. tsurumi@immunbio.mpg.de

The Journal of Cell Biology
|December 22, 2004
PubMed

Insights

Mouse oocytes utilize spindle assembly checkpoint (SAC) proteins for meiosis I and II checkpoints. However, unlike frog eggs, the SAC is not essential for maintaining metaphase arrest in mouse oocytes.

Area of Science:

  • Cell biology
  • Developmental biology
  • Reproductive biology

Background:

  • The spindle assembly checkpoint (SAC) is crucial for accurate chromosome segregation.
  • Bub1 kinase plays a known role in SAC function during meiosis II arrest in Xenopus oocytes.

Purpose of the Study:

  • To determine if SAC-mediated inhibition of the anaphase-promoting complex/cyclosome (APC/C) maintains metaphase arrest in mouse oocytes.
  • To investigate the role of SAC proteins in cytostatic factor (CSF)-induced arrest.

Main Methods:

  • Injection of dominant-negative Bub1 mutant (Bub1dn) into mouse oocytes.
  • In vitro meiosis progression analysis.
  • Assessment of metaphase II arrest following CSF release and nocodazole treatment.

Main Results:

  • Disruption of SAC by Bub1dn accelerated meiosis I passage but did not prevent metaphase II arrest.
  • Bub1dn-injected oocytes entered interphase upon CSF release and spindle disruption, unlike controls.
  • Similar results observed with dominant-negative Mad2, BubR1, and APC/C-activating Cdc20 mutants.

Conclusions:

  • SAC proteins are required for checkpoint functions in both meiosis I and II in mouse oocytes.
  • The SAC is not required for establishing or maintaining CSF arrest in mouse oocytes, contrasting with findings in frog eggs.

More Related Videos

Meiotic Spindle Assessment in Mouse Oocytes by siRNA-mediated Silencing09:16

Meiotic Spindle Assessment in Mouse Oocytes by siRNA-mediated Silencing

Published on: October 11, 2015

Multi-Photon Laser Ablation of Cytoplasmic Microtubule Organizing Centers in Mouse Oocytes08:24

Multi-Photon Laser Ablation of Cytoplasmic Microtubule Organizing Centers in Mouse Oocytes

Published on: November 11, 2022

Related Concept Videos

The Spindle Assembly Checkpoint02:19

The Spindle Assembly Checkpoint

The spindle assembly checkpoint is a molecular surveillance mechanism ensuring the fidelity of chromosome segregation during anaphase. The checkpoint monitors the completion of all the prerequisite steps before chromosome segregation to determine whether the segregation process should proceed or be delayed.
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
The Spindle Assembly Checkpoint02:19

The Spindle Assembly Checkpoint

The spindle assembly checkpoint is a molecular surveillance mechanism ensuring the fidelity of chromosome segregation during anaphase. The checkpoint monitors the completion of all the prerequisite steps before chromosome segregation to determine whether the segregation process should proceed or be delayed.
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
Meiosis II01:57

Meiosis II

Meiosis II is the second and final stage of meiosis. It relies on the haploid cells produced during meiosis I, each of which contain only 23 chromosomes—one from each homologous initial pair. Importantly, each chromosome in these cells is composed of two joined copies, and when these cells enter meiosis II, the goal is to separate such sister chromatids using the same microtubule-based network employed in other division processes. The result of meiosis II is two haploid cells, each containing...
Meiosis II02:02

Meiosis II

Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
Separation of Sister Chromatids02:17

Separation of Sister Chromatids

At the transition from prophase to metaphase, there is a reduction in cohesion along the chromosomal arms, resulting in the resolution of sister chromatids. However, residual cohesin connections remain to hold the sister chromatids together until the transition from metaphase to anaphase. The residual connection prevents any premature separation of sister chromatids, blocking the risks of aneuploidy within the daughter cells.
At the onset of anaphase, separase, a proteolytic enzyme, is...
Spindle Assembly02:50

Spindle Assembly

Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...