Project description: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.
Project description: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.
Project description:Yeast cells can be affected during their growth to several stress conditions. One of the most known and characterised is the osmotic stress and most of the studies about osmotic sterss response in yeast have been focused on salt or sorbitol stress. However, during yeast growth in industrially relevant processes (for instance throughout alcoholic fermentation on the must to produce alcoholic beverages) the osmotic stress is mainly due to the high sugar(in particular glucose) concentration (200-250 g/L).