Figure 10. Growing (A) and nitrogen starved (B) yeast cells illustrating thet starved cells complete cycles without growth and generate very tiny cells from new buds; all cells end up arrested in G1 as unbudded cells. Reprinted from ref 17 with permission.

Growth and division John Pringle became interested in the regulation of growth in the cell cycle. Williamson and Scopes had found that stationary cultures of yeast cells were unbudded. John Pringle and Gerry Johnston followed up on this and showed that growth is integrated with the division cycle prior to budding, once again at the CDC28 step. They found that cells were able to complete the cell cycle after abrupt nitrogen starvation in the absence of any net growth, but did not start new cell cycles (Fig. 10). However, if division was interrupted with a cell cycle mutation, the growth of the cell continued unabated for several hours.