Figure 4.

cdr2⁺ mRNA is constant during the cell cycle and in nitrogen starvation conditions. (A) Cells of a cdc25–22 strain (JK1864) were arrested in late G2 by a temperature shift to 35.5°C for 4 h and then released from the arrest by a temperature shift to 25°C. Samples were taken during the block and every 20 min after the shift to permissive temperature. The percentage of cells with septa was determined by counting ∼200 cells at each time point. Northern blot analysis of cdr2⁺ and cdc22⁺ mRNA was performed. Ethidium bromide staining of ribosomal RNA shown below indicates that an approximately equal amount of RNA was loaded in each lane. (B) Cells of a wild-type strain (PR109) were grown to midlog phase in EMM2 and washed and resuspended in EMM2-N. At intervals after starvation, samples were taken and Northern blot analysis was performed.