Description of Experiments:

Time courses after nitrogen starvation:
h90 fus1-B20, h-, h+, or h90 ste11Δ cells were grown in minimal medium (EMM) containing NH4Cl as a nitrogen source, washed with minimal medium without NH4Cl (EMM-N) and resuspended in EMM-N. Cells were then grown at 28°C and samples taken every hour for 5 hours.

Direct comparisons of h90 fus1 and h90 ste11Δ:
Cells were treated as described above and samples were taken after 5 hours at 28°C. This experiment was carried out four times.

Overexpression of ste11:
Cells carrying a plasmid containing ste11 under the control of the nmt1 thiamine-repressible promoter (pREP1-ste11) or an empty vector (pREP1) were grown in EMM containing thiamine. Cells were washed with EMM without thiamine (EMM-T), resuspended in EMM-T and grown at 32°C for 18 hours. The experiment was performed three times in P cells and three times in M cells.

P factor time course:
sxa2Δ h- cells were grown in EMM, washed with EMM-N, resuspended in EMM-N and grown for 5 hours at 28°C. The culture was split in half and P factor (at a final concentration of 1.5 µg/ml) or a corresponding amount of ethanol was added to the cells. Samples were taken at 0, 0.5, 1 and 2 hours.