|
|
|
|
|
|
|
||
J. Cell Biol.,
Volume 140, Number 6, March 23, 1998 1417-1426
§
* Department of Cell Biology, University of Massachusetts Medical Center, Shrewsbury, Massachusetts 01655; Centrosomes repeatedly reproduce in sea urchin zygotes arrested in S phase, whether cyclin-dependent kinase 1-cyclin B (Cdk1-B) activity remains at
prefertilization levels or rises to mitotic values. In contrast, when zygotes are arrested in mitosis using cyclin
B Laboratory of
Cell Regulation, Division of Molecular Medicine, Wadsworth Center, Albany, New York 12201-0509; and § Department of
Biomedical Sciences, State University of New York, Albany, NewYork 12222
-90, anaphase occurs at the normal time, yet centrosomes do not reproduce. Together, these results reveal the cell cycle stage specificity for centrosome reproduction and demonstrate that neither the level nor
the cycling of Cdk1-B activity coordinate centrosome
reproduction with nuclear events. In addition, the proteolytic events of the metaphase-anaphase transition
do not control when centrosomes duplicate. When we
block protein synthesis at first prophase, the zygotes divide and arrest before second S phase. Both blastomeres contain just two complete centrosomes, which
indicates that the cytoplasmic conditions between mitosis and S phase support centrosome reproduction.
However, the fact that these daughter centrosomes do
not reproduce again under such supportive conditions
suggests that they are lacking a component required for
reproduction. The repeated reproduction of centrosomes during S phase arrest points to the existence
of a necessary "licensing" event that restores this component to daughter centrosomes during S phase, preparing them to reproduce in the next cell cycle.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
