Project description:Background: Microorganisms are the major cause of food spoilage during storage, processing and distribution. Pseudomonas fluorescens is a typical spoilage bacterium that contributes to a large extent to the spoilage process of proteinaceous food. RpoS is considered an important global regulator involved in stress survival and virulence in many pathogens. Our previous work revealed that RpoS contributed to the spoilage activities of P. fluorescens by regulating resistance to different stress conditions, extracellular acylated homoserine lactone (AHL) levels, extracellular protease and total volatile basic nitrogen (TVB-N) production. However, RpoS-dependent genes in P. fluorescens remained undefined. Results: RNA-seq transcriptomics analysis combined with quantitative proteomics analysis basing on multiplexed isobaric tandem mass tag (TMT) labeling was performed for the P. fluorescens wild-type strain UK4 and its derivative carrying a rpoS mutation. A total of 375 differentially expressed genes (DEGs) and 212 differentially expressed proteins (DEPs) were identified in these two backgrounds. The DGEs were further verified by qRT-PCR tests, and the genes directly regulated by RpoS were confirmed by 5’-RACE-PCR sequencing. The combining transcriptome and proteome analysis revealed a role of this regulator in several cellular processes, including polysaccharide metabolism, intracellular secretion and extracellular structures, cell well biogenesis, stress responses, ammonia and biogenic amine production, which may contribute to biofilm formation, stress resistance and spoilage activities of P. fluorescens. Moreover, in this work we indeed observed that RpoS contributed to the production of the macrocolony biofilm’s matrix.
Project description:PIWI-interacting RNAs (piRNAs) mediate transposable element (TE) silencing at the transcriptional or post-transcriptional level in animal gonads. In the Drosophila ovary, Piwiâ??piRNA complexes (Piwiâ??piRISCs) repress TE transcription by modifying the chromatin state, such as H3K9me3 marks. Here, we demonstrate that Piwi physically interacts with linker histone H1. Depletion of Piwi decreases H1 density on target loci, leading to TE derepression. Loss of H1 results in gain of chromatin accessibility at target loci without affecting H3K9me3 and heterochromatin protein 1a (HP1a) density at the same loci. Piwi-mediated TE silencing also requires HP1a by regulating chromatin accessibility through its association with target loci. Thus, Piwiâ??piRISCs require both H1 and HP1a to repress TEs, and the silencing is correlated with the state of chromatin formation rather than H3K9me3 marks. These findings suggest that Piwiâ??piRISCs regulate the interaction of chromatin components with target loci to maintain silencing of the TE state through the modulation of chromatin accessibility. RNA levels, H1 and H3K9me3 occupancy, chromatin accessibility, and Piwi-associated small RNA levels in ovarian somatic cells (OSC) depleted of piRNA pathway components and H1.
Project description:Multiplexed Chromatin Conformation Capture in Mouse Erythroid cells , from hundreds of targeted loci, using agilent oligo capture technology and high throughput sequencing. Two erythroid Ter119+ cell replicates and a mouse ES cell control
Project description:Transposable elements (TEs) occupy large fraction of metazoan genomes and pose constant threat to genomic integrity. This threat is particularly critical in germ cells, as changes in the genome that are induced by TEs will be transmitted to the next generation. Small non-coding piwi interacting (pi)RNAs recognize and silence a diverse set of TEs in germ cells. In mice, piRNA-guided transposon repression correlates with establishment of CpG DNA methylation on their sequences, yet the mechanism and the spectrum of genomic targets of piRNA silencing are unknown. Here we show that in addition to DNA methylation, the piRNA pathway is required to maintain a high level of the repressive H3K9me3 histone modification on long interspersed nuclear elements (LINEs) in germ cells. piRNA-dependent chromatin repression targets exclusively full-length elements of actively transposing LINE families, demonstrating the remarkable ability of the piRNA pathway to recognize active elements among the large number of genomic transposon fragments. Total of 34 libraries were analyzed. In case of ChIP libraries, every 'input' sample was used for normalization of the respective ChIP (H3K9me3 or H3) sample; the input libraries preceed ChIP libraries in the list below. There are four replicates (input-ChIP pairs) for H3K9me3 ChIP on liver cells, two for ChIP on testicular somatic cells for each genotype (Miwi2 Het and KO); and four for ChIP on male germ cells for each genotype (one from FACS-sorted germ cells, and three from MACS-sorted germ cells). Each replicate has a Het/KO pair, and the respective libraries were cloned from the material isolated from littermates. One H3 ChIP for each genotype is included, with respective inputs.
Project description:Genome Wide Association Studies (GWAS) have been successful in yielding >60 loci for Systemic Lupus Erythematosus (SLE). However, it is known that GWAS just reports genomic signals and not necessarily the precise localization of culprit genes, with eQTL efforts only able to infer causality to a minority of such loci. Thus, we sought to carry out physical and direct ‘variant to gene mapping’ by integrating results from high-throughput chromatin conformation capture and ATAC-seq assays. This experiment refers to the chromatin conformation capture part of our work. Detecting contacts between distant regions of the genome offers a powerful opportunity to understand GWAS signals that principally reside in non-coding regions, and thus likely act as regulatory elements for neighboring genes. To move beyond analyzing one locus at a time and to improve on the low resolution of available Hi-C data, we employed a massively parallel, high resolution Capture-C based method to simultaneously characterize the genome-wide interactions of all human promoters in any cell type. We applied this approach to study the promoter ‘interactome’ of primary human T Follicular Helper (TFH) cells from tonsils of healthy volunteers (3 biological replicates), a model relevant to SLE as TFH operate upstream of the activation of pathogenic autoantibody-producing B cells during the disease. We also analyzed the promoter interactome of naive CD4-positive helper T cells (3 biological replicates). We designed a custom Agilent SureSelect library targeting both ends of DpnII restriction fragments that overlap promoters of protein-coding, noncoding, antisense, snRNA, miRNA, snoRNA and lincRNA transcripts. Each library was sequenced on 8 lanes of an Illumina HiSeq 4000.
Project description:We employed a massively parallel, high resolution Capture-C based method to simultaneously characterize the genome-wide interactions of all human promoters in any cell type. We applied this approach to study the promoter interactome of HepG2 cells (3 biological replicates). We designed a custom Agilent SureSelect library targeting both ends of DpnII restriction fragments that overlap promoters of protein-coding, noncoding, antisense, snRNA, miRNA, snoRNA and lincRNA transcripts. Each library was sequenced on 4 lanes of an Illumina HiSeq 4000.
Project description:We used ATAC-seq (Buenrostro et al, 2013) to identify regions of open chromatin in FACS sorted mouse endothelial cells from E12.5 hearts. Please note that the animals were injected at different dates, which resulted in different effects of the knockout, as indicated in the batch attribute of the samples. This data set is part of the study \Endocardial Tbx20 is essential for mesenchymal and myocardial cell movements required for cardiac septation\. Peaks were called using HOMER (-gsize 1.87e9 -region -tbp 1). Replicate 1: -fdr 1e-8, replicate 2: default parameters. Buenrostro JD, Giresi PG, Zaba LC, Chang HY, Greenleaf WJ. 2013. Transposition of native chromatin for fast and sensitive epigenomic profiling of open chromatin, DNA-binding proteins and nucleosome position. Nat Methods 10: 12138.