Thymidine starvation
Ontology highlight
ABSTRACT:
ORGANISM(S): Escherichia coli
PROVIDER: GSE147758 | GEO | 2022/10/11
REPOSITORIES: GEO
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Project description:C. glutamicum strains adapted to higher growth temperatures were obtained through an adaptive laboratory evolution experiment. To elucidate molecular basis for thermotolerance acquired by the evolved strains, we examined transcriptional responses of the evolved and parental strains to thermal stress using microarray technology.
2015-01-06 | GSE64654 | GEO
Project description:C. glutamicum strains adapted to higher growth temperatures were obtained through an adaptive laboratory evolution experiment. To elucidate molecular basis for thermotolerance acquired by the evolved strains, we examined transcriptional responses of the evolved and parental strains to thermal stress using microarray technology. Each strain was grown at the optimal growth temperature (33 M-bM-^DM-^C). When OD610 reached around 7, the growth temperature increased to 41 M-bM-^DM-^C, and transcriptional changes of the evolved and parental strains were examined with microarray technology.
2015-01-06 | E-GEOD-64654 | biostudies-arrayexpress
Project description:A population of Saccharomyces cerevisiae was cultured for approximately 450 generations in the presence of high glucose to select for genetic variants. This experiment allows for a controlled model of adaptive evolution under natural selection. Using the parental strain BY4741 as the starting population, an evolved culture was obtained after continuous aerobic growth in a glucose-high medium for approximately 450 generations. After the evolution period three single colony isolates were selected for analysis. Next-generation Ion Torrent sequencing was used to evaluate genetic changes. Greater than 100 deletion/insertion changes were found with approximately half of these effecting genes. Additionally, over 180 single-nucleotide polymorphisms (SNPs) were identified with more than one quarter of these resulting in a non-synonymous mutation. Affymetrix DNA microarrays and RNseq analysis were used to determine differences in gene expression in the evolved strains compared to the parental strain. It was established that approximately 900 genes demonstrated significantly altered expression in the evolved strains relative to the parental strain. Many of these genes showed similar alterations in their expression in all three evolved strains. Interestingly, genes with altered expression in the three evolved strains included genes with a role in the TCA cycle. Overall these results are consistent with the physiological observations of decreased ethanol production and suggest that the underlying metabolism switched from fermentation to respiration during aerobic growth.
2012-07-11 | GSE36518 | GEO
Project description:A population of Saccharomyces cerevisiae was cultured for approximately 450 generations in the presence of high glucose to select for genetic variants. This experiment allows for a controlled model of adaptive evolution under natural selection. Using the parental strain BY4741 as the starting population, an evolved culture was obtained after continuous aerobic growth in a glucose-high medium for approximately 450 generations. After the evolution period three single colony isolates were selected for analysis. Next-generation Ion Torrent sequencing was used to evaluate genetic changes. Greater than 100 deletion/insertion changes were found with approximately half of these effecting genes. Additionally, over 180 single-nucleotide polymorphisms (SNPs) were identified with more than one quarter of these resulting in a non-synonymous mutation. Affymetrix DNA microarrays and RNseq analysis were used to determine differences in gene expression in the evolved strains compared to the parental strain. It was established that approximately 900 genes demonstrated significantly altered expression in the evolved strains relative to the parental strain. Many of these genes showed similar alterations in their expression in all three evolved strains. Interestingly, genes with altered expression in the three evolved strains included genes with a role in the TCA cycle. Overall these results are consistent with the physiological observations of decreased ethanol production and suggest that the underlying metabolism switched from fermentation to respiration during aerobic growth. Yeast strains were grown in the presence of high glucose for approximately 450 generations. Individual isolates were then grown and total RNA was collected to compare difference between the evolved strains and the parental strain.
2012-07-10 | E-GEOD-36518 | biostudies-arrayexpress
Project description:The experimental evolution of laboratory populations of microbes provides an opportunity to observe the evolutionary dynamics of adaptation in real time.Until very recently, however, such studies have been limited by our inability to systematically find mutations in evolved organisms.We overcome this limitation by using a variety of DNA microarray-based techniques to characterize genetic changes, including point mutations, structural changes, and insertion variation, that resulted from the experimental adaptation of 24 haploid and diploid cultures of Saccharomyces cerevisiae to growth in glucose-, sulfate, or phosphate-limited chemostats for ~ 200 generations.We identified frequent genomic amplifications and rearrangements as well as novel retrotransposition events associated with adaptation.Global mutation detection in 10 clonal isolates identified 32 point mutations. On the basis of mutation frequencies, we infer that these mutations and the subsequent dynamics of adaptation are determined by the batch phase of growth prior to initiation of continuous phase in the chemostat.We relate these genotypic changes to phenotypic outcomes, namely global patterns of gene expression, and to increases in fitness by 5-50%. We found that the spectrum of available mutations in glucose or phosphate-limited environments combined with the batch phase population dynamics early in our experiments to allow several distinct genotypic and phenotypic evolutionary pathways in response to these nutrient limitations. By contrast, sulfate-limited populations were much more constrained in both genotypic and phenotypic outcomes.Thus, the reproducibility of evolution varies with specific selective pressures reflecting the constraints inherent in the system-level organization of metabolic processes in the cell.We were able to relate some of the observed adaptive mutations (e.g. transporter gene amplifications) to known features of the relevant metabolic pathways, but many of the mutations pointed to genes not previously associated with the relevant physiology. Thus, in addition to answering basic mechanistic questions about evolutionary mechanisms our work suggests that experimental evolution can also shed light on the function and regulation of individual metabolic pathways. Keywords: gene expression, CGH, and TSE analysis consult individual records for details of analysis This Dataset consists of several experiments: Gene expression experiments found in Figure 1a of paper: Design: RNA from each evolved clone or population grown in chemostat culture is compared to RNA from matching ancestor strains grown in the same conditions. Samples: GSM339025-GSM339088 CGH experiments found in Figure 2A, Figure 3, and Table S2: Experiment design: DNA from each evolved clone or population is hybridized vs DNA from the matched ancestor strain Samples: GSM339089-GSM339146 CGH experiments found in Table S3: Experiment design: DNA from each segregant derived from an evolved strain is hybridized vs DNA from the matched ancestor strain Samples: GSM339147-GSM339158 Gel band CGH experiments found in Figure S1: Experiment design: Chromosomes from evolved strains were run on a gel and excised. DNA from the bands is hybridized vs matched ancestor genomic DNA Samples: GSM339159-GSM339184 TSE CGH experiments found in Table S4: Experiment design: DNA linked to Ty1/Ty2 sequences was extracted from evolved strains and ancestor strains, and compared to ancestral extracted or genomic DNA as indicated. Samples: GSM339185-GSM339212 CGH experiments for experiments in Figure S7: Experiment design: DNA from 2 strains transformed with a SUL1 plasmid hybridized vs DNA from the matched ancestor strain Samples: GSM339213 and GSM339214
2010-05-18 | E-GEOD-13435 | biostudies-arrayexpress
Project description:Saccharomyces cerevisiae has been used as a secretion host for production of various products, including pharmaceuticals. However, few antibody molecules have been functionally expressed in S. cerevisiae due to the incompatible surface glycosylation. Our laboratory previously isolated a group of yeast mutant strains with different α-amylase secretory capacities, and these evolved strains have showed advantages for production of some heterologous proteins. However, it is not known whether these secretory strains are generally suitable for pharmaceutical protein production. Here, three non-glycosylated antibody fragments with different configurations (Ran-Fab fragment Ranibizumab, Pex-the scFv peptide Pexelizumab, and Nan-a single V-type domain) were successfully expressed and secreted in three background strains with different secretory capacities, including HA (wild type), MA (evolved strain), and LA (evolved strain). However, the secretion of Ran and Nan were positively correlated with the strains’ secretory capacity, while Pex was most efficiently secreted in the parental strain. Therefore, transcriptional analysis was performed to explore the fundamental changes triggered by the expression of the different pharmaceutical proteins in these selected yeast strains.
2021-07-06 | GSE179391 | GEO
Project description:Comparing the transcriptional responses of Bacillus subtilis strains WN624 and WN1106 at 5 kPa and 101 kPa. WN1106 is a 5 kPa-evolved strain with increased fitness compared to ancestor-WN624 strain at 5 kPa. This experiment probed the difference in response when the strains are grown at 5 kPa.
2014-03-14 | GSE50653 | GEO
Project description:Wine produced at low temperature is often considered to improve sensory qualities. However, there are certain drawbacks to low temperature fermentations: e.g. low growth rate, long lag phase, and sluggish or stuck fermentations. Selection and development of new Saccharomyces cerevisiae strains well adapted at low temperature is interesting for future biotechnological applications. This study aimed to select and develop wine yeast strains that well adapt to ferment at low temperature through evolutionary engineering, and to decipher the process underlying the obtained phenotypes. To this end, we used a pool of 27 commercial yeast strains and set up batch serial dilution experiments to mimic wine fermentation conditions at 12 ºC. Evolutionary engineering was accomplished by using the natural yeast mutation rate and mutagenesis procedures. One strain (P5) outcompeted the others under both experimental conditions and was able to impose after 200 generations. The evolved strains showed improved growth and low-temperature fermentation performance compared to the ancestral strain. This improvement was acquired only under inositol limitation. The transcriptomic comparison between the evolved and parental strains showed the greatest up-regulation in four mannoprotein coding genes, which belong to the DAN/TIR family (DAN1, TIR1, TIR4 and TIR3). Genome sequencing of the evolved strain revealed the presence of a SNP in the GAA1 gene and the construction of a site-directed mutant (GAA1Thr108) in a derivative haploid of the ancestral strain resulted in improved fermentation performance. GAA1 encodes a GPI transamidase complex subunit that adds GPI, which is required for inositol synthesis, to newly synthesized proteins, including mannoproteins. Thus we demonstrate the importance of inositol and mannoproteins in yeast adaptation at low temperature and the central role of the GAA1 gene by linking both metabolisms. The first aim of this study was to assess the most competitive strains that grow under wine fermentation conditions at low temperature. To this end, we performed a growth competition assay with 27 commercial wine strains inoculated at equal population size in synthetic grape must. In spite of the economical and industrial importance of these strains, their phenotypic variation in the main enological traits, particularly those related to optimum growth temperature, and their ability to adapt to low temperature fermentation have been poorly investigated. The second goal was to obtain an improved strain to grow and ferment at low temperature by evolutionary engineering. For this purpose, we maintained growth competition in synthetic grape must during 200 generations to select for the mutations that produce phenotypes with improved growth in this medium. One of these evolved cultures was previously treated with ethyl methanesulfonate (EMS) to increase the mutation rate. Finally, we aimed to decipher the molecular basis underlying this improvement by analyzing the genomic and transcriptional differences between the parental strain and the strain evolved at low temperature.
2015-03-31 | E-GEOD-67428 | biostudies-arrayexpress