Related Experiment Video
Updated: Feb 20, 2026

Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1
Published on: February 25, 2016
Cyclin B1 is essential for mitosis in mouse embryos, and its nuclear export sets the time for mitosis
Bernhard Strauss1,2, Andrew Harrison1,2, Paula Almeida Coelho3
1The Gurdon Institute, Cambridge, England, UK.
Abstract:
There is remarkable redundancy between the Cyclin-Cdk complexes that comprise the cell cycle machinery. None of the mammalian A-, D-, or E-type cyclins are required in development until implantation, and only Cdk1 is essential for early cell divisions. Cyclin B1 is essential for development, but whether it is required for cell division is contentious. Here, we used a novel imaging approach to analyze Cyclin B1-null embryos from fertilization onward. We show that Cyclin B1-/- embryos arrest in G2 phase after just two divisions. This is the earliest arrest of any Cyclin known and places Cyclin B1 with cdk1 as the essential regulators of the cell cycle. We reintroduced mutant proteins into this genetically null background to determine why Cyclin B1 is constantly exported from the nucleus. We found that Cyclin B1 must be exported from the nucleus for the cell to prevent premature entry to mitosis, and retaining Cyclin B1-Cdk1 at the plasma membrane precludes entry to mitosis.
More Related Videos
08:33Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis
Published on: December 5, 2017
10:54Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
Published on: September 17, 2012
Related Concept Videos
M-Cdk Drives Transition Into Mitosis
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
Positive Regulator Molecules
Positive Regulator Molecules
Meiosis II
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 Chromatids
At the onset of anaphase, separase, a proteolytic enzyme, is...
Mitogens and the Cell Cycle