Figure 6.

Expression of CycD cyclins during the cell cycle in synchronous BY-2 cells. Cells were synchronized in the early S phase with aphidicolin (Methods) in two independent experiments. Progress of cells through the cell cycle was monitored by following changes in DNA synthesis and mitotic index. A, In the first experiment, progress of cells was followed for one complete cell cycle. B, Cells were harvested at the indicated times for RNA analysis and blots were hybridized with the probes indicated. Note that no sample was taken at 2 h. EF-1α, Elongation factor 1α. C, In a second synchrony experiment, progress through two cell cycles was followed. Changes in DNA synthesis were monitored between 0 to 6 and 17 to 26 h, the times when the two S phases were predicted to occur. D, Cells in the S phase (S) or mitosis (M) were collected at the indicated times for RNA analysis. Samples from stationary cells and cells treated with aphidicolin for 24 h (before washing and release into synchrony) are included for comparison. RNA gel blots were hybridized to the probes indicated.