>To the ongoing discussion about obtaining cells synchronized in the
>cycle I would like to add the following warning: The synchronization
>by transient cell arrest in the cycle induces growth imbalance and
>dramatically alters expression of cyclins and other cell cycle
>regulatory proteins. For example after double thymidine block we have
>observed "unscheduled" expression of cyclins B1 and A in cells at the
>G1/S boundary, over five-fold increase in expression of cyclin E, and
>40% increased total protein content [Gong et al., Cell Growth &
>Differentiation, 6: (November issue) 1485-93, 1995]. Kinetic and
>metabolic properties of so synchronized cells are much different
>compared to the cells from asynchronous, exponentially growing
>cultures.
>Zbigniew Darzynkiewicz
>
>
Dr. Darzynkiewicz brings up a good point. Chemical synchronization can lead
to metabolic imbalances that may invalidate or seriously compromise research
data. It is almost always preferable sychronize cells "naturally": mitotic
shake off or centrifugal elutriation.
Thomas L. Morgan, Ph.D.
Department of Radiation Oncology
Kaiser Permanente Medical Center
Los Angeles, CA 90027
morgantl@aol.com