Stress responses elicited by glucose withdrawal in Aspergillus fumigatus
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ABSTRACT:
ORGANISM(S): Aspergillus fumigatus
PROVIDER: GSE216000 | GEO | 2022/12/09
REPOSITORIES: GEO
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2014-07-28 | E-GEOD-56622 | biostudies-arrayexpress
Project description:Bacteria have to continuously adjust to nutrient fluctuations from favorable to less favorable conditions and carbon starvation. The glucose-acetate transition followed by carbon starvation is representative of such carbon fluctuations observed by E. coli in many environments. Regulation of gene expression through fine-tuning of mRNA pools constitutes one of the regulation levels required for such a metabolic adaptation. It results from both mRNA transcription and degradation controls. However, the contribution of transcript stability regulation in gene expression is poorly characterized. Using combined transcriptome and mRNA decay analyses, we investigated (i) how transcript stability changes in E. coli during the glucose-acetate-starvation transition and (ii) if these changes contribute to gene expression changes. Our work highlights that transcript stability increases along carbon depletion. Most of the stabilization occurs at glucose-acetate transition when glucose is exhausted, then stabilized mRNAs remain stable during acetate consumption and carbon starvation. Meanwhile, expression of most genes is downregulated and we observed three time less gene expression upregulation. Using control analysis theory on 375 genes, we show that most of gene expression regulation is driven by changes in transcription. Although mRNA stabilization is not the controlling phenomenon, it contributes to the emphasis or attenuation of transcription regulation. However, upregulation of 18 genes (33% of our studied upregulated set) is mainly governed by transcript stabilization. Because these genes are associated with response to nutrient changes and stress, this illustrates the importance of post-transcriptional regulations in bacterial response to nutrient starvation.
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Project description:Bacteria have to continuously adjust to nutrient fluctuations from favorable to less favorable conditions and carbon starvation. The glucose-acetate transition followed by carbon starvation is representative of such carbon fluctuations observed by E. coli in many environments. Regulation of gene expression through fine-tuning of mRNA pools constitutes one of the regulation levels required for such a metabolic adaptation. It results from both mRNA transcription and degradation controls. However, the contribution of transcript stability regulation in gene expression is poorly characterized. Using combined transcriptome and mRNA decay analyses, we investigated (i) how transcript stability changes in E. coli during the glucose-acetate-starvation transition and (ii) if these changes contribute to gene expression changes. Our work highlights that transcript stability increases along carbon depletion. Most of the stabilization occurs at glucose-acetate transition when glucose is exhausted, then stabilized mRNAs remain stable during acetate consumption and carbon starvation. Meanwhile, expression of most genes is downregulated and we observed three time less gene expression upregulation. Using control analysis theory on 375 genes, we show that most of gene expression regulation is driven by changes in transcription. Although mRNA stabilization is not the controlling phenomenon, it contributes to the emphasis or attenuation of transcription regulation. However, upregulation of 18 genes (33% of our studied upregulated set) is mainly governed by transcript stabilization. Because these genes are associated with response to nutrient changes and stress, this illustrates the importance of post-transcriptional regulations in bacterial response to nutrient starvation.
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Project description:Cultivation methods used to investigate microbial calorie restriction often result in carbon and energy starvation. This study aims to dissect cellular responses to calorie restriction and starvation in Saccharomyces cerevisiae by using retentostat cultivation. In retentostats, cells are continuously supplied with a small, constant carbon and energy supply, sufficient for maintenance of cellular viability and integrity but insufficient for growth. When glucose-limited retentostats cultivated under extreme calorie restriction were subjected to glucose starvation, calorie-restricted and glucose-starved cells were found to share characteristics such as increased heat-shock tolerance and expression of quiescence-related genes. However, they also displayed strikingly different features. While calorie-restricted yeast cultures remained metabolically active and viable for prolonged periods of time, glucose starvation resulted in rapid consumption of reserve carbohydrates, population heterogeneity due to appearance of senescent cells and, ultimately, loss of viability. Moreover, during starvation, calculated rates of ATP synthesis from storage carbohydrates were 2-3 orders of magnitude lower than steady-state ATP-turnover rates calculated under extreme calorie restriction in retentostats. Stringent reduction of ATP turnover during glucose starvation was accompanied by a strong down-regulation of genes involved in protein synthesis. These results demonstrate that extreme calorie restriction and carbon starvation represent different physiological states in S. cerevisiae. The yeast was first grown for 14 days under extreme calorie restriction in anaerobic, glucose-limited retentostats (Boender et al., 2009, Appl.Environ.Microbiol., 75: 5607-5614.). Subsequently, starvation was started by terminating the glucose feed. Yeast transcriptional reprogramming in response to calorie restriction and starvation was monitored by microarray analysis. Independent duplicate retentostat cultures, and subsequently starvation, were sampled for transcriptome analysis using Affymetrix microarrays. One time-point was sampled during calorie restriction (T0) and four time points were sampled during the starvation phase 10, 30, 60 and 120 minutes after switching of the feed, resulting in a dataset of 10 arrays.
2011-08-15 | E-GEOD-22602 | biostudies-arrayexpress