Project description:Responses of Escherichia coli as they recover from one stationary phase in 10 mM Na-P + 0.2 % glucose at OD 0.4 Keywords: time course
Project description:S. typhimurium 14028 wt, hfq and smpB were harvested from log phase LB (LBlog); (2), stationary phase LB (LBstat); (3) 4h MgM medium pH 5.0 after resuspension of LB stat culture (MgMshock); and (4) log phase MgM medium pH5.0 after 100fold dilution of an LB stat culture (MgMDil). Total RNA was extracted, cDNA labeled and hybridized to a non-redundant Salmonella whole genome PCR product ORF array. S. typhimurium 14028 cells were harvested, on three separate days, (1), after growth at 30°C to log phase in LB (LBlog); (2), after growth at 30°C to stationary phase in LB (LBstat); (3) after transfer of a stationary phase culture grown in LB into magnesium-deficient MgM medium [100 mM Tris-Cl, 5 mM KCl, 7.5 mM (NH4)2SO4, 0.5 mM K2SO4, 1 mM KH2PO4, 0.2% glycerol, 0.1% Casamino acids, 8uM MgCl2] pH 5.0 and growth for four more hours at 30°C (MgMshock); (4) after 100fold dilution of a stationary phase culture grown in LB into magnesium-deficient MgM medium pH5.0 and growth at 30°C to log phase (MgMDil). This procedure was performed on (A), wild type [WT] cells; (B), cells of an hfq- (STM4361) knockout mutant; and (C), cells of an smpB- (STM2688) knockout mutant, resulting in 36 samples total. Total RNA was extracted, cDNA labeled with Cy5-dCTP and hybridized versus Cy3-labeled 14028 gDNA to a non-redundant Salmonella whole genome PCR product ORF array.
Project description:Background: Global patterns of gene expression of Escherichia coli K-12 during growth transitions have been deeply investigated, however, comparable studies of E. coli O157:H7 have not been explored, particularly with respect to factors regulating virulence genes and genomic islands specific to this pathogen. To examine the impact of growth phase on the dynamics of the transcriptome, O157:H7 Sakai strain was cultured in MOPS minimal media (0.1% glucose), RNA harvested at 10 time points from early exponential to full stationary phase, and relative gene expression was measured by co-hybridization on high-density DNA microarrays. Results: Analysis of variance (R/MAANOVA, Fs test) identified 442 (36%) of 1239 O157-specific ORFs and 2110 (59%) of 3647 backbone ORFs that changed in expression significantly over time. QT cluster analysis placed 2468 of the 2552 significant ORFs into 12 groups; each group representing a distinct expression pattern. ORFs from the largest cluster (n=1078) decreased in expression from late exponential to early stationary phase: most of these ORFs are involved in functions associated with steady state growth. Also represented in this cluster are ORFs of the TAI island, encoding tellurite resistance and urease activity, which decreased ~4-fold and most ORFs of the LEE island, which decreased ~2-fold by early stationary phase. ORFs encoding proteins secreted via the LEE encoded type III secretion system, such as tccP and espJ, also decreased in expression from exponential to stationary phase. Three of the clusters (n=154) comprised genes that are transiently upregulated at the transition into stationary phase and included genes involved in nutrient scavenging. Upregulated genes with an increase in mRNA levels from late exponential to early stationary phase belonged to one cluster (n=923) which includes genes involved in stress responses (e.g. gadAB, osmBC, and dps). These transcript levels remained relatively high for >3h in stationary phase. The Shiga toxin genes (stx1AB and stx2B) were significantly induced after transition into stationary phase. Conclusions: Expression of 307 O157-specific ORFs was modulated in a growth dependent manner. These results provide a baseline transcriptional profile that can be compared to patterns of gene expression of this important foodborne pathogen under adverse environmental conditions. Keywords: time course
Project description:Flag-YBX1 overexpressed T24 cells pellets were resuspended with 2 volume of lysis buffer (150 mM KCl, 10 mM HEPES pH 7.6, 2 mM EDTA, 0.5% NP-40, 0.5 mM DTT, 1:100 protease inhibitor cocktail, 400 U/ml RNase inhibitor), and incubated at 4 °C for 30 min with rotation. Then the lysate was centrifuged at 15 000 g for 20 min. Before incubating the lysate with Flag beads, 100ul were taken as input. The anti-Flag M2 magnetic beads (Sigma, 10 μl per mg lysate) were washed with NT2 buffer (200 mM NaCl, 50 mM HEPES pH 7.6, 2 mM EDTA, 0.05% NP-40, 0.5 mM DTT, 200 U/ml RNase inhibitor) four times. Cell lysate was mixed with M2 beads and incubated at 4 °C for 4 h with rotation. The beads were washed two times with 1 ml ice-cold NT2 buffer. Then the beads were subject to Micrococal nuclease (NEB) digestion (1:1 000 000 dilution) for 8 min at 37 °C. The beads were cooled on ice immediately for 5 min and washed two times with 1 ml ice-cold 1× PNK+EGTA buffer (50 mM Tris-HCl pH 7.5, 20 mM EDTA, 0.05% NP-40, 200 U/ml RNase inhibitor) and two times with 1 ml ice-cold 1× PK buffer (50 mM NaCl, 100 mM Tris-HCl pH 7.5, 10 mM EDTA, 0.2% SDS, 200 U/ml RNase inhibitor). Then the beads were digested with 200 μl pre-heated (20 min at 50 °C) Proteinase K and RNAs were extracted with an equal volume of Acid-Phenol: Chloroform, pH 4.5 (Ambion). The RNAs were subjected to rRNA removal and Bisseq. The libraries were sequenced on the Illumina HiSeq X-Ten platform at Novogene (Tianjin, CA) with paired-end 150 bp read length.The m5C sites were called using meRanCall from meRanTK (FDR < 0.01).