|
|
|
|
|
|
|
||
J. Cell Biol.,
Volume 140, Number 6, March 23, 1998 1285-1295
Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
In proliferating cells, DNA synthesis must be
performed with extreme precision. We show that
groups of replicons, labeled together as replicon clusters, form stable units of chromosome structure. HeLa
cells were labeled with 5-bromodeoxyuridine (BrdU) at
different times of S phase. At the onset of S phase, clusters of replicons were activated in each of ~750 replication sites. The majority of these replication "foci" were
shown to be individual replicon clusters that remained
together, as stable cohorts, throughout the following 15 cell cycles. In individual cells, the same replication foci
were labeled with BrdU and 5-iododeoxyuridine at the
beginning of different cell cycles. In DNA fibers, 95%
of replicons in replicon clusters that were labeled at the
beginning of one S phase were also labeled at the beginning of the next. This shows that a subset of origins
are activated both reliably and efficiently in different cycles.
The majority of replication forks activated at the onset of S phase terminated 45-60 min later. During this
interval, secondary replicon clusters became active.
However, while the activation of early replicons is synchronized at the onset of S phase, different secondary
clusters were activated at different times. Nevertheless, replication foci pulse labeled during any short interval
of S phase were stable for many cell cycles. We propose
that the coordinated replication of related groups of
replicons, that form stable replicon clusters, contributes
to the efficient activation and propagation of S phase in
mammalian cells.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
