Project description:Peanut (Arachis hypogaea) has a large (~2.7 Gbp) allotetraploid genome with closely related component genomes making its genome very challenging to assemble. Here we report genome sequences of its diploid ancestors (A. duranensis and A. ipaënsis). We show they are similar to the peanut’s A- and B-genomes and use them use them to identify candidate disease resistance genes, create improved tetraploid transcript assemblies, and show genetic exchange between peanut’s component genomes. Based on remarkably high DNA identity and biogeography, we conclude that A. ipaënsis may be a descendant of the very same population that contributed the B-genome to cultivated peanut. Whole Genome Bisulphite Sequencing of the peanut species Arachis duranensis and Arachis ipaensis.
Project description:Replication of the eukaryotic genome occurs in the context of chromatin, a nucleoprotein packaging state consisting of repeating nucleosomes. Chromatin is commonly thought to carry epigenetic information from one generation to the next, although it is unclear how such information survives the disruptions of nucleosomal architecture that occur during genomic replication. Here, we sought to directly measure a key aspect of chromatin structure dynamics during replication – how rapidly nucleosome positions are established on the newly-replicated daughter genomes. By isolating newly-synthesized DNA marked with the nucleotide analogue EdU, we characterize nucleosome positions on both daughter genomes of budding yeast during a time course of chromatin maturation. We find that nucleosomes rapidly adopt their mid log positions at highly-transcribed genes, and that this process was impaired upon treatment with the transcription inhibitor thiolutin, consistent with a role for transcription in positioning nucleosomes in vivo. Additionally, experiments in the Hir1Δ background reveal a role for HIR in nucleosome spacing. Using strand-specific EdU libraries, we characterize nucleosome positions on the leading and lagging strand daughter genomes, uncovering differences in chromatin maturation dynamics between the two daughter genomes at hundreds of genes. Our data define the maturation dynamics of newly-replicated chromatin, and support a role for transcription in sculpting the chromatin template. We have mapped changes in nucleosome positions on newly replicated DNA in a timecourse after genome replication. We have used Micrococcal Nuclease footprinting of cross linked chromatin to determine nucleosome positions and EdU (ethylene deoxy uridine) to mark nascent DNA strands. EdU incorporated into nascent DNA strands was biotinylated with Click chemistry and nascent DNA strand fragments were subsequently isolated using Streptavidin coated magnetic beads.
Project description:ChIP-seq data characterizing the occupancy of TFAM over the mitochondrial and nuclear genomes in HeLa cells. Characterization of mitochondrial and nuclear genome-wide TFAM binding in HeLa cells
Project description:This data set comprises population (47 samples) measurements of transcription factor DNA binding (PU.1 and RPB2) and histone modification (H3K27ac, H3K4me1 and H3k4me3) levels for a subset of the 1000 Genomes Project CEPH samples. This data was generated as part of the following study: - Population Variation and Genetic Control of Modular Chromatin Architecture in Humans. Cell. 2015 Aug 27;162(5):1039-50. doi: 10.1016/j.cell.2015.08.001. Epub 2015 Aug 20. An additional set of 111 samples from the 1000 Genomes Project (GBR and TSI populations) were also assayed for three histone modifications (H3K27ac, H3K4me1 and H3k4me3). This data was generated as part of the following study: - Chromatin 3D interactions mediate genetic effects on regulatory networks.
Project description:Somatic genome rearrangements are thought to play important roles in cancer development. We optimized a long span paired-end-tag (PET) sequencing approach using 10 Kb genomic DNA inserts to study human genome structural variations (SVs). The use of 10 Kb insert size allows the identification of breakpoints within repetitive or homology containing regions of a few Kb in size and results in a higher physical coverage compared to small insert libraries with the same sequencing effort. We have applied this approach to comprehensively characterize the SVs of 15 cancer and 2 non-cancer genomes and used a filtering approach to strongly enrich for somatic SVs in the cancer genomes. Our analyses revealed that most inversions, deletions, and insertions are germline SVs, whereas tandem duplications, unpaired inversions, inter-chromosomal translocations, and complex rearrangements are overrepresented among somatic rearrangements in cancer genomes. We demonstrate that the quantitative and connective nature of DNA-PET data is precise in delineating the genealogy of complex rearrangement events, we observe signatures which are compatible with breakage-fusion-bridge cycles, and discover that large duplications are among the initial rearrangements that trigger genome instability for extensive amplification in epithelial cancers. Structural variations of 15 human cancer samples and 2 human normal samples were identified by long span paired-end sequencing
Project description:11 Mycobacterium tuberculosis mutants resistant to D-cycloserine were isolated in the laboratory. Genomic DNA was isolated and whole genomes were sequenced to perform SNP calling and identify possible mutations associated with resistance.
Project description:Definition of functional regulatory regions in the vast non-coding fractions of mammalian genomes remains a daunting challenge that underscores our limited understanding of mammalian gene regulation. Genome sequencing of many mammals has recently been exp
Project description:Nucleosome positioning dictates the DNA accessibility for regulatory proteins, and thus is critical for gene expression and regulation. It has been well documented that only a subset of nucleosomes are reproducibly positioned (phased) in eukaryotic genomes. The most prominent example of phased nucleosomes is the context of genes, where phased nucleosomes flank the transcriptional starts sites (TSSs). It is unclear, however, what factors influence nucleosome phasing in regions that are not close to genes. We performed a combinational mapping of nucleosome positioning and DNase I hypersensitive sites (DHSs) across the rice genome. We discovered that DHSs located in a variety of contexts, both genic and intergenic, were flanked by strongly phased nucleosome arrays. Our results support the barrier model for nucleosome organization as a general feature of eukaryote genomes, including plant genomes, and not limited to TSSs. Specifically, regions bound with regulatory proteins, including intergenic regions, can serve as barriers that organize phased nucleosome arrays on both sides. Our results also suggest that rice DHSs often span a single, phased nucleosome, similar to the H2A.Z-containing nucleosomes observed in DHSs in the human genome. We propose that genome-wide nucleosome positioning in the eukaryotic genomes is orchestrated by genomic regions associated with regulatory proteins. Rice chromatin was digested by micrococcal nuclease (MNase) into mono-nucleosome size. Mono-nucleosomal DNA was isolated and sequenced (MNase-seq) using Illumina sequencing platforms. We obtained a total of 38 million (M) single-end reads from our first MNase-seq experiment and mapped ~26 M to unique positions in the rice genome. We also conducted pair-end sequencing of an independent MNase-seq library, obtained 274 M paired-end reads, and mapped ~231 M read pairs to unique positions in the rice genome.We applied a strategy of combinational mapping of nucleosome positioning and DHSs (GSE26610) to examine whether nucleosome positioning is associated with all cis-regulatory elements in the rice genome. All datasets used in the analysis were developed using rice leaf tissue in the same developmental stage