Project description:E. coli cultures were exposed to tellurite 0.5 µg/ml during 15 min. Total RNA was extracted and cDNA labeled probes were generated by reverse transcription using Alexa 555 and Alexa 647 fluorophores. These probes were used to hybridize genomic slides containing genomic arrays to determine global transcriptional changes.
Project description:E. coli cultures were exposed to tellurite 0.5 µg/ml during 15 min. Total RNA was extracted and cDNA labeled probes were generated by reverse transcription using Alexa 555 and Alexa 647 fluorophores. These probes were used to hybridize genomic slides containing genomic arrays to determine global transcriptional changes. Two-conditions experiment, antibacterial vs. Untreated control cells. Biological replicates: 2 control, 2 toxicants exposed cells, independently grown and harvested. One replicate per array. Dye swap conditions.
Project description:Transcriptional profiling comparing Escherichia coli simultaneously exposed to tellurite and CTX with untreated control cells; Tellurite with control; CTX with control
Project description:Transcriptional profiling comparing Escherichia coli simultaneously exposed to tellurite and CTX with untreated control cells; Tellurite with control; CTX with control Three-condition experiment, antibacterial (tellurite; CTX or tellurite/CTX) vs. Untreated control cells. Biological replicates: 3 control, 3 toxicants exposed cells, independently grown and harvested. One replicate per array.
Project description:E. coli cultures were exposed to green or red CdTe Quantum Dots 50 µg/ml during 15 min. Total RNA was extracted and cDNA labeled probes were generated by reverse transcription using Alexa 555 and Alexa 647 fluorophores. These probes were used to hybridize genomic slides containing genomic arrays to determine global transcriptional changes.
Project description:Transcriptional profiles of uropathogenic Escherichia coli CFT073 exposed to cranberry-derived proanthocyanidins (PACs) were determined. Our results indicate that bacteria grown on media supplemented with PACs were iron-deprived. To our knowledge, this is the first time that PACs have been shown to induce a state of iron-limitation in this bacterium. Cultures of E. coli CFT073 were streaked onto LB agar plates and incubated (37°C, 24 h). A single colony was inoculated into 150 mL of LB broth. Three inoculated flasks contained LB broth alone (controls), and three inoculated flasks were supplemented with cranberry PACs (100 µg/mL). After incubation (37°C, 5 h, 200 rpm to mid-log growth phase), bacteria were harvested for RNA extraction.
Project description:Alkylation damage to DNA occurs when cells encounter alkylating agents in the environment or when active alkylators are generated by nitrosation of amino acids in metabolic pathways. To cope with DNA alkylation damage, cells have evolved genes that encode proteins with alkylation-specific DNA repair activities. It is notable that these repair systems are conserved from bacteria to humans. In Escherichia coli, cells exposed to a low concentration of an alkylating agent, such as N-methyl-Nâ-nitro-N-nitrosoguanidine (MNNG) or methyl methanesulfonate (MMS), show a remarkable increase in resistance to both the lethal and mutagenic effects of subsequent high-level challenge treatments with the same or other alkylating agents. This increased resistance has been known as âadaptive responseâ to alkylation damage in DNA. To date, four genes have been identified as components of this response, ada, alkA, alkB and aidB. The ada gene encodes the Ada protein, which has the dual function of a transcriptional regulator for the genes involved in the adaptive response, and a methyltransferase that demethylates two methylated bases (O6meG and O4meT) and methylphosphotriesters produced by methylating agents in the sugar phosphate backbone. The differences between the wild-type and mutant strains were characterized at transcriptome levels. In addition, the global changes in gene expressions in response to alkylating agents (MMS), in E. coli K-12 W3110 and ada mutant strains were also analyzed. The analysis of time- and strain-dependent adaptive responses revealed the regulatory and physiological characteristics of the Ada-dependent adaptive response in E. coli. In order to examine the intracellular changes that are induced by the ada gene deletion in the MMS-untreated, normal growth condition, the expression levels of genes of ada mutant cells were compared with those of wild-type cells at the mid-log growth phase (at 0.5 h sampling point). Cells were cultivated at 37oC and 250 rpm in 100 mL of Luria-Bertani (LB) medium (10 g/L tryptone, 5 g/L yeast extract, and 5 g/L NaCl) in 250-mL Erlenmeyer flasks. Transcriptome analysis were also performed for the samples (E. coli wildtype and ada mutant strains) taken at 0.5, 1.5 and 3.9 h following MMS treatment for both MMS-treated and -untreated control cultures, and the expression levels were compared.
Project description:Investigation of whole transcriptional changes in F. verticillioides FRC M-3125 when exposed to 5 μg/ml pyrrocidine A (PA), 20 μg/ml pyrrocidine B (PB), 50 μg/ml 2-benzoxazolinone (BOA), 50 μg/ml 2-oxindole (OXD), 50 μg/ml 2-coumaranone (CMN), or 50 μg/ml chlorzoxazone (CZX). Cultures were harvested one hour after exposure. Assessed in reference to control cultures of M-3125 exposed to DMSO (0.5% final concentration) since all the above compounds were dissolved in DMSO.
Project description:The effect of an extracellular acid shift on gene expression profiles of Escherichia coli K-12 W3110 was observed using Affymetrix E. coli arrays. In order to maximize aeration and maintain logarithmic growth, the overnight culture (LBK broth medium) was diluted 500-fold into a 250-ml baffled flask containing 55 ml of 20mM HOMOPIPES buffered medium (pH 7.6). Cultures were grown to OD600=0.2. A shift to acid external pH was conducted by rapid addition of 840 µl 1M HCl, which lowered the pH of the medium to pH 5.5. For each of five biological replicates, 10-ml samples were taken at times 0, 1, 5, and 10 min post addition of HCl. Each sample was added to 1 ml 10% phenol-ethanol stop solution in <5 sec. For each sample, cDNA synthesized from total RNA was hybridized onto Affymetrix E. coli arrays. Model-based gene expression intensities were determined using GCOS software. Gene-by-gene temporal differential expression was analyzed as a mixed-effects model using polynomial time functions as fixed effects and flask variation as a random effect. Keywords: Time Course