Strains devoid of ppGpp (relA spoT; called ppGpp0), and ppGpp0 dksA- exhibit several amino acid requirements for growth on minimal media. We found that overexpression of DksA can complement some of those requirements. Since DksA is a factor that binds to the RNA polymerase secondary channel, we wondered if other secondary channel proteins might also exert a similar role with respect to growth on minimal media. In our study we found that GreA and partially GreB can in fact complement these requirements under certain conditions. Here, we wished to investigate a broader effect of GreA and GreB on ppGpp0 and ppGpp0 dksA- strains. Since the parent strains are unable to grow in minimal media, we had to supplement the M9 glucose medium with a set of amino acids (DFHILQSTV). We found that both, GreA and GreB can affect a much larger set of genes in the absence of dksA, than in its presence. Also, GreA seems to affect more genes than GreB, under both conditions.
Effects on growth by changes of the balance between GreA, GreB, and DksA suggest mutual competition and functional redundancy in Escherichia coli.
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Combinatorial recruitment of CREB, C/EBPβ and c-Jun determines activation of promoters upon keratinocyte differentiation.
Specimen part, Treatment
View SamplesCombinatorial recruitment of CREB, C/EBPb and Jun determines activation of promoters upon keratinocyte differentiation
Combinatorial recruitment of CREB, C/EBPβ and c-Jun determines activation of promoters upon keratinocyte differentiation.
Specimen part, Treatment
View SamplesWe used FACS isolated RD cone photoreceptors from C3H mice (we refer this mouse model as f-RD) that were transfected by AAVs to express fluorescent reporters to genomic analyses. We tested three different ages.
Genetic reactivation of cone photoreceptors restores visual responses in retinitis pigmentosa.
Age, Specimen part, Treatment
View SamplesThe ability to isolate pure pancreatic -cells would greatly aid multiple areas of diabetes research. We developed an exendin-4-like neopeptide conjugate for the rapid purification and isolation of functional pancreatic -cells. By targeting the glucagon-like peptide-1 receptor, -cells were isolated within an hour and were >99% pure. These studies were confirmed by immunostaining, confocal microscopy and microarray analysis on isolated cells. Gene expression profiling studies of the cytofluorometrically sorted -cells provided new insights into the genetic programs at play of different ages and stages during type-1 diabetes development. The described isolation method should have broad applicability to the -cell field.
Rapid, high efficiency isolation of pancreatic ß-cells.
Sex, Age, Specimen part
View SamplesGene expression array analysis component. Ligand-dependent transcription by the nuclear receptor glucocorticoid receptor (GR) is mediated by interactions with co-regulators. The role of these interactions in determining selective binding of GR to regulatory elements remains unclear. Recent findings indicate a large fraction of genomic GR binding coincides with chromatin that is accessible prior to hormone treatment, suggesting that receptor binding is dictated by proteins that maintain chromatin in an open state. Combining nucleolytic cleavage and chromatin immunoprecipitation with high-throughput sequencing, we identify the activator protein 1 (AP1) as a major partner for productive GR-chromatin interactions. AP1 is critical for GR-regulated transcription and recruitment to co-occupied regulatory elements, illustrating an extensive AP1-GR interaction network. Importantly, the maintenance of baseline chromatin accessibility facilitates GR recruitment and is dependent on AP1 binding. We propose a model where the basal occupancy of transcription factors act to prime chromatin and direct inducible transcription factors to select regions in the genome.
Transcription factor AP1 potentiates chromatin accessibility and glucocorticoid receptor binding.
Sex, Cell line, Treatment, Time
View SamplesStudies of the Xenopus organizer have laid the foundation for our understanding of the conserved signaling pathways that pattern vertebrate embryos during gastrulation. Here, we use this wealth of knowledge as leverage in the design and analysis of a genomic visualization of organizer-related gene transcription. Using ectopic expression of the two major activities of the organizer, BMP and Wnt inhibition, as well as endogenous tissues, we generate a focused set of samples that represent different aspects of organizer signaling. The genomic expression values of each sample are then measured with oligonucleotide arrays. From this data, genes regulated by organizer signaling are selected and then clustered by their patterns of regulation. A new GO biological process annotation of the Xenopus genome allows us to rapidly identify clusters that are highly enriched for known gastrula patterning genes. Within these clusters, we can predict the expression patterns of unknown genes with remarkable accuracy, leading to the discovery of new organizer-related gastrula stage expression patterns for 19 genes. Moreover, the patterns of gene response observed within these clusters allow us to parse apart the contributions of BMP and Wnt inhibition in organizer function. We find that the majority of gastrula patterning genes respond transcriptionally to these activities according to only a few stereotyped patterns, allowing us to describe suites of genes that are likely to share similar regulatory mechanisms. These suites of genes demonstrate a mechanism where BMP inhibition initiates the organizer program before gastrulation, and Wnt inhibition maintains and drives the organizer program during gastrulation.
Genomic analysis of Xenopus organizer function.
Specimen part
View SamplesWe used microarrays to provide a transcriptomic signature of different types of cholestasis evoked by 3 different drugs and obstructive surgery
Robustness testing and optimization of an adverse outcome pathway on cholestatic liver injury.
Specimen part, Cell line, Treatment
View SamplesMany of the genes coding for secreted protein effectors are arranged in gene clusters in the genome of the biotrophic plant pathogen Ustilago maydis. The largest of these gene clusters, cluster 19A, encodes 24 secreted effectors. Deletion of the entire cluster results in severe attenuation of virulence. The generation and analysis strains carrying sub-deletions identified 9 genes significantly contributing to tumor formation after seedling infection. As the individual contributions of these genes to tumor formation were small, we studied the response of maize plants to the whole cluster mutant as well as to several individual mutants by array analysis. This revealed distinct plant responses, demonstrating that the respective effectors have discrete plant targets. Many of the genes coding for secreted protein effectors are arranged in gene clusters in the genome of the biotrophic plant pathogen Ustilago maydis. The largest of these gene clusters, cluster 19A, encodes 24 secreted effectors. Deletion of the entire cluster results in severe attenuation of virulence. The generation and analysis strains carrying sub-deletions identified 9 genes significantly contributing to tumor formation after seedling infection. As the individual contributions of these genes to tumor formation were small, we studied the response of maize plants to the whole cluster mutant as well as to several individual mutants by array analysis. This revealed distinct plant responses, demonstrating that the respective effectors have discrete plant targets.
Characterization of the largest effector gene cluster of Ustilago maydis.
Specimen part, Treatment
View SamplesWe investigated genome-wide gene alterations in the temporal cortex of a well-characterized cohort of Alzheimers disease (AD) patients using Affymetrix exon arrays.
Genome wide profiling of altered gene expression in the neocortex of Alzheimer's disease.
Sex, Age, Specimen part, Disease
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