BioProject

Saccharomyces cerevisiae is one of the most well-studied model organisms used in the scientific community. More...

Saccharomyces cerevisiae is one of the most well-studied model organisms used in the scientific community. Its ease of manipulation, accessible growth conditions, short life cycle, and conserved eukaryotic metabolic pathways make it a useful model organism. Consequently, yeast has been used to investigate a myriad of phenomena, from microbial to human studies. Most of the research performed using this model organism utilizes yeast cell populations when they are growing exponentially, a growth phase aptly termed exponential or log phase. However, log phase encompasses several yeast generations and ranges several hours of yeast growth, meaning that there is a potential for variability during this “homogenous” growth phase. Cells in log phase require robust ribosome biogenesis to support their rapid growth and cell division. Interestingly, during log phase, ribosomal RNA (rRNA) synthesis (which is the first and rate limiting step in ribosome biosynthesis) has been shown to decrease prior to growth rate decline in stationary phase. In this study, we utilized several genomic and biochemical methods to elucidate the relationship between subphases of log phase and rRNA synthesis. Our results indicate that as yeast cells progress through subphases of log growth both of Pol I transcription and rRNA processing are repressed. Overall, this study establishes a growth phase dependent control of rRNA synthesis that unexpectedly begins prior to the switch to stationary phase (i.e. pre-diauxic shift) as a putative mechanism of anticipating nutrient starvation. Overall design: WT yeast strain was grown at 30oC and harvested at the indicated OD600. For each growth timepoint three biological replicates were obtained. NET-seq libraries were then prepared for each sample. Less...