Formation of Polyribosomes during Recovery from Contact Inhibition of Replication
نویسندگان
چکیده
Previous studies (3) of colony formation of 3T3, a cell line with the property of contact inhibition of replication, demonstrated a coincidence of cell contact and cessation of DNA synthesis and replication . Also, plating efficiency tests (3, 6) from monolayer cultures of 3T3 consistently have been in the range of 20%-30% for exponentially growing cells as well as cells in the state of contact inhibition of replication (CI culture), whether in fresh medium or medium from the CI culture . This suggested that the inhibition of macromolecular synthesis and replication was a reversible and inherent property of the 3T3 cell rather than a depletion of the medium or physiological condition of the cells . A temporary release of the CI culture can be achieved either by dispersing the cells so that they are no longer in contact with other cells or by changing to fresh medium (5) . Todaro et al. (5) showed that immediately after a change of medium the cells of a confluent culture underwent a wave of RNA synthesis and that a small fraction of cells eventually completed DNA synthesis and mitosis. The discovery that saline medium without fresh serum could also elicit a stimulation of RNA synthesis (6) led to the hypothesis that an inhibitor of cellular replication exists in confluent cultures of 3T3 . In that study the evidence suggested that confluent cultures of 3T3 released a diffusible substance which enabled them to sustain a state of contact inhibition of replication . The site of action of the low molecular weight inhibitor was related to cellular RNA synthesis. In this report we have examined the effects of contact inhibition of replication on the polyribosome (polysome) content in the cell line 3T3 . MATERIALS AND METHODS
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عنوان ژورنال:
- The Journal of Cell Biology
دوره 49 شماره
صفحات -
تاریخ انتشار 1971