Sporulation_sum1_del_transfer_to_YPD. Saccharomyces cerevisiae

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 Overall design: sum1 deleted SK1 cells (JPY214) 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 6 hours of the sporulation process, cells were kept for RNA extraction. Part of the culture was centrifuged and resuspended in YPD, and was monitored 20 and 40 minutes after the transfer.

本研究采用全基因组表达谱分析，探究出芽酵母细胞如何获得孢子发生（sporulation）的细胞定型（commitment）。将处于孢子发生不同阶段的产孢细胞转移至生长培养基中，并对其转录应答特征进行表征。多数孢子发生诱导基因在转移后即刻出现下调，即便在仍持续进行孢子发生的定型细胞中亦是如此。预定型细胞或转移至生长培养基的成熟孢子的代谢相关转录应答，本质上与暴露于葡萄糖的营养体细胞的转录应答一致。与之形成鲜明对比的是，定型细胞则激发出独特且差异显著的应答反应。本研究结果表明，酵母细胞并非通过稳定孢子发生过程来确保其细胞定型，而是通过主动调控自身的信息处理过程，以环境特异性的方式优化孢子发生进程。
关键词：时间序列（Time course）
整体实验设计：将SUM1基因敲除的SK1菌株细胞（JPY214）在YPD培养基（2%酵母提取物、4%细菌蛋白胨、4%葡萄糖）中培养至饱和状态，培养时长为24小时；随后将其稀释至YPA培养基（1%酵母提取物、2%细菌蛋白胨、1%乙酸钾）中过夜培养。随后用无菌水将细胞洗涤两次，并重悬于SPM培养基（0.3%乙酸钾、0.02%棉子糖）中以启动孢子发生过程。在孢子发生进程进行至6小时时，收集部分细胞用于RNA提取。将剩余部分培养物离心收集，并重悬于YPD培养基中，分别在转移后的20分钟和40分钟对其进行监测。