Sporulation_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 Wild type SK1 cells (NKY1551) 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. Part of that culture was used as reference for all hybridizations preformed in this study. 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 different stages of the sporulation process (2, 3, 4, 5, 6, 7, 8, 9 and 10 hours) RNA was extracted for microarray hybridizations. At each hour, part of the culture was centrifuged and resuspended in YPD. Each YPD culture was monitored immediately after the transfer, after 20 and 40 minutes.