Project description:Open chromatin provides access to a wide spectrum of DNA binding proteins for DNA metabolism processes such as transcription, repair, recombination, and replication. In this regard, open chromatin profiling has been widely used to identify the location of regulatory regions, including promoters, enhancers, insulators, silencers, replication origins, and recombination hotspots. For a quantitative getic analysis of chromatin regulation, we generated open chromatin maps of 100 yeast samples including the parental strains (BY and RM, and two replicates for each) and their descendants by using the FAIRE-seq technique Open chromatin in two parental strains and 94 segregants of their crossing
Project description:Open chromatin provides access to a wide spectrum of DNA binding proteins for DNA metabolism processes such as transcription, repair, recombination, and replication. In this regard, open chromatin profiling has been widely used to identify the location of regulatory regions, including promoters, enhancers, insulators, silencers, replication origins, and recombination hotspots. For a quantitative getic analysis of chromatin regulation, we generated open chromatin maps of 100 yeast samples including the parental strains (BY and RM, and two replicates for each) and their descendants by using the FAIRE-seq technique
Project description:We report the application of single myofiber ATAC-Seq (smfATAC-Seq) to investigate the chromatin accessibility of a single myofiber without the presence of confounding muscle resident cell types. This method demonstrates that open chromatin regions of myonuclei can be tagmentated and high-quality sequencing ready libraries can be generated from these fragments. To perform comparative analysis as well as to demonstrate the applicability of the smfATAC-Sew to study changes in chromatin of myonuclei within different contexts, smfATAC-Seq was performed both on uninjured myofibers as well as injured myofibers seven days after induced injury. Furthermore, ATAC-Seq on 5000 muscle stem cells (MuSCs) was also performed according to the previously described OMNI ATAC-Seq protocol (Corces, M.R. et al. Nature Methods, 2017) in order to compare the sequencing quality of the smfATAC-Seq as well as to demonstrate the changes in open chromatin that occur from the stem cell state to the fully differentiated myofibers. smfATAC-seq resulted in comparable coverage and sequencing depth to the ATAC-seq performed on MuSCs and allowed for peak calling and differential peak analysis. These analysis revealed that the open chromatin state of uninjured and injured myofibers after seven days are mostly similar although some regions invovled in immune response remain in an open state in the injured myofibers compared to the uninjured myofibers and the regions involved in structural formation of the muscle are more accessible in the case of regeneration. Even though certain differences in the open chromatin are observed, smfATAC-Seq analysis suggest that overall, the open chromatin state of the myonuclei returns back to homeostasis after seven days of regeneration. Furthermore, smfATAC-Seq comparison with the ATAC-Seq from MuSCs show the differences in open chromatin regions between these conditions. Increased accessibility of genes involved in myogenesis and structural components can be observed in the myofibers compared to MuSCs while MuSCs show increased accessibility in regions involved in membrane permeability and signalling pathways. In addition, the regions that are accessible for both conditions include genes involved in mitochondrial transport, regulation of transcription and regulation of metabolites and energy. Overall, this study introduces smfATAC-Seq that succesfully assesses the genome-wide chromatin accessibility of a single myofiber with relatively high sequencing depth. The smfATAC-Seq can be used to perform comparative analysis between different conditions such as injury. However, this method can be readily applied to study differences between young and old myofibers or in the context of muscular dystrophy, cachexia, and exercise.
Project description:Genomic enhancers regulate spatio-temporal gene expression by recruiting specific combinations of transcription factors (TFs). When TFs are bound to active regulatory regions, they displace canonical nucleosomes, making these regions biochemically detectable as nucleosome-depleted regions or accessible/open chromatin. Here we ask whether open chromatin profiling can be used to identify the entire repertoire of active promoters and enhancers underlying tissue-specific gene expression during normal development and oncogenesis in vivo. To this end, we first compare two different approaches to detect open chromatin in vivo using the Drosophila eye primordium as a model system: FAIRE-seq, based on physical separation of open versus closed chromatin; and ATAC-seq, based on preferential integration of a transposon into open chromatin. We find that both methods reproducibly capture the tissue-specific chromatin activity of regulatory regions, including promoters, enhancers, and insulators. Using both techniques, we screened for regulatory regions that become ectopically active during Ras-dependent oncogenesis, and identified 3778 regions that become (over-)activated during tumor development. Next, we applied motif discovery to search for candidate transcription factors that could bind these regions and identified AP-1 and Stat92E as key regulators. We validated the importance of Stat92E in the development of the tumors by introducing a loss of function Stat92E mutant, which was sufficient to rescue the tumor phenotype. Additionally we tested if the predicted Stat92E responsive regulatory regions are genuine, using ectopic induction of JAK/STAT signaling in developing eye discs, and observed that similar chromatin changes indeed occurred. Finally, we determine that these are functionally significant regulatory changes, as nearby target genes are up- or down-regulated. In conclusion, we show that FAIRE-seq and ATAC-seq based open chromatin profiling, combined with motif discovery, is a straightforward approach to identify functional genomic regulatory regions, master regulators, and gene regulatory networks controlling complex in vivo processes. FAIRE-Seq in Drosophila wild type eye-antennal imaginal discs (2 wt strains); ATAC-Seq in Drosophila wild type eye-antennal imaginal discs (3 wt strains) ; FAIRE-Seq in Drosophila Ras/Scrib induced eye disc tumors (1 early and 1 late); ATAC-Seq in Drosophila Ras/Scrib induced eye disc tumors (1 early and 1 late); ATAC-Seq in Drosophila eye discs with Unpaired over-expression (2 biological replicates); CTCF ChIP-seq in Drosophila eye discs; ChIP-seq input in Drosophila eye discs
Project description:Background Compelling evidence indicates that Shigella species, the etiologic agents of bacillary dysentery, as well as enteroinvasive Escherichia coli, are derived from multiple origins of Escherichia coli and form a single pathovar. To further understand the genome diversity and virulence evolution of Shigella, comparative genomic hybridization microarray analysis was employed to compare the gene content of E. coli K-12 with those of 43 Shigella strains from all serotypes. Results For the 43 strains subjected to CGH microarray analyses, the common backbone of the Shigella genome was estimated to contain more than 1,900 open reading frames, with a mean number of 729 undetectable ORFs. The mosaic distribution of absent regions indicated that insertions and/or deletions have led to the highly diversified genomes of pathogenic strains. Conclusion These results support the hypothesis that by gain and loss of functions, Shigella species became successful human pathogens through convergent evolution from diverse genomic backgrounds. Moreover, we also found many specific differences between different lineages, providing a window into understanding bacterial speciation and taxonomic relationships. Keywords: comparative genomic hybridization
Project description:Examination of open chromatin regions between clonal neutrophil progenitor populations. Conditionally immortalized CD45.1 naive paired granulocyte-monocyte progenitors (GMPs) and their mature neutrophil counterpart were profiled in an in vitro cell system. We identified 29,966 differentially accessible regions (DARs) between GMPs and neutrophils, from a total of 74,009 consensus peaks of chromatin accessibility. There is some correlation of open chromatin between GMP and mature neutrophil clones.
Project description:Micrococcal nuclease was used to digest mESC nuclei under a mild digestion condition to release the relatively open chromatin, and under an extensive digestion condition to release the genome chromatin. By comparing the genome distribution of mono-nucleasome under these two conditions, open chromatin regions were detected. One mild digestion and one extensive digestion was applied to the mESC cells, followed by sequencing.
Project description:We mapped open chromatin by FAIRE-seq and measured gene expression by RNA-seq in 3 types of Drosophila samples: staged whole embryos, imaginal discs, pharate appendages. We first demonstrate that regions of open chromatin precisely define regions of enhancer activity in developing embryos. In contrast to the dynamic changes in open chromatin observed between different stages of embryogenesis, we found that the open chromatin profiles in wing, leg, and haltere imaginal discs are nearly identical. This was also true again later in development, where the adult appendages also share nearly identical open chromatin profiles. Therefore, at a given developmental time point, different appendages are specified using a shared set of DNA regulatory elements. However, from one time point to the next, the set of accessible regulatory elements changes. Open chromatin profiles in appendage imaginal discs are almost entirely different than those of the adult appendages. We propose that master regulator transcription factors create morphologically distinct structures by differentially influencing the function of the same set of DNA regulatory modules. Open chromatin profiling during Drosophila development: 3 stages of embryogenesis (2-replicates each); wing, leg, and haltere 3rd instar imaginal discs (3-replicates each); 3rd larval central nervous system (2-replicates); eye-antennal imaginal discs (2-replicates); wing, leg, and haltere pharate appendages (2-replicates each); Genomic DNA Inputs. Sequencing performed on Illumina GAII and HiSeq.
Project description:Genome-wide comparative analyses of the open chromatin profiles between equivalent stages of mouse and pig limb bud development reveal the extensive functional divergence of their limb regulomes. These alterations affect evolutionary conserved regions located in the genomic landscapes of genes with essential functions during limb development. This analysis uncovers the widespread regulatory changes that appear to underlie the morphological diversion of the artiodactyl limb from the pentadactyl blueprint of tetrapods.
Project description:Genome-wide comparative analyses of the open chromatin profiles between equivalent stages of mouse and pig limb bud development reveal the extensive functional divergence of their limb regulomes. These alterations affect evolutionary conserved regions located in the genomic landscapes of genes with essential functions during limb development. This analysis uncovers the widespread regulatory changes that appear to underlie the morphological diversion of the artiodactyl limb from the pentadactyl blueprint of tetrapods.