Quiescent yeast cells exhibit a rapid response to oxidative stress.
Anthony D. Aragon, Gabriel A. Quinones, Margaret Werner-Washburne
Biology, University of New Mexico, Castetter Hall, Albuquerque, NM, 87131, USA
Quiescence is a critical and surprisingly dynamic phase of the yeast life cycle. Because survival in and exit from the quiescent state is important in both health and disease, a better understanding of this phase is essential. Through transcriptional profiling, we assessed the ability of quiescent cells to respond to oxidative stress (50uM menadione). Initial results showed a massive response to this stress within 30-minutes. A newly developed rapid sampler was used to harvest cells for further characterization of the kinetics of this response at the genomic level. Analysis of two time-courses (using 1 min and 10s intervals, respectively) revealed a 2-8 fold increase in about 600 mRNAs within 80s after exposure to menadione. The majority of the 'induced' genes encode ribosomal proteins or proteins involved in ribosome biogenesis. Because the response is so rapid, we believe it is not likely to be the result of transcription and, to our knowledge, is the first time this type of response has been observed in yeast. We hypothesize that quiescent cells, and, by inference, other types of cells, maybe primed to respond quickly to environmental changes through non-transcriptional increases in specific mRNAs. One possible mechanism would be by cells sequestering almost full-length transcripts until they are needed. Further analysis of this response will be presented.
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