Sporulation_SPS4_NDT80_transfer_to_YPD

We have used genome-wide expression profiling to investigate how budding yeast cells become committed to sporulation. Sporulating cells were transferred to growth medium at different stages of the process, and their transcription response was characterized. Most sporulation-induced genes were immediately down-regulated upon the transfer, even in committed cells that continued to sporulate. The metabolic-related transcription response of pre-committed cells or of mature spores transferred to growth medium was essentially the same as that of vegetative cells exposed to glucose. In contrast, committed cells elicited a unique, and dramatically different response. Our results suggest that cells ensure commitment to sporulation not by stabilizing the process, but by modulating their information processing in an active manner that may optimize sporulation in an environment-specific manner. Keywords: Time course SK1 cells, in which NDT80 is expressed under the promoter of SPS4 (GF18), were grown to saturation in YPD (2% yeast extract, 4% bactopeptone, 4% glucose) for 24 hours, diluted into YPA (1% yeast extract, 2% bactopeptone 1% Potassium Acetate) and grown overnight. The cells were then washed twice with sterile water and resuspended in SPM media (0.3% Potassium Acetate and 0.02% Rafinose) to initiate the sporulation process. At 5.5 hours of the sporulation process, cells were kept for RNA extraction. Part of the culture was centrifuged and resuspended in YPD, and was monitored immediately, 20 and 40 minutes after the transfer.