Project description:Nucleosomes package eukaryotic DNA and are composed of four different histone proteins, H3, H4, H2A and H2B. Histone H3 has two main variants, H3.1 and H3.3, which show different genomic localization patterns in animals. We profiled H3.1 and H3.3 variants in the genome of the plant Arabidopsis thaliana and show that the localization of these variants shows broad similarity in plants and animals, in addition to some unique features. H3.1 was enriched in silent areas of the genome including regions containing the repressive chromatin modifications H3 lysine 27 methylation, H3 lysine 9 methylation, and DNA methylation. In contrast, H3.3 was enriched in actively transcribed genes, especially peaking at the 3’ end of genes, and correlated with histone modifications associated with gene activation such as histone H3 lysine 4 methylation, and H2B ubiquitylation, as well as by RNA Pol II occupancy. Surprisingly, both H3.1 and H3.3 were enriched on defined origins of replication, as was overall nucleosome density, suggesting a novel characteristic of plant origins. Our results are broadly consistent with the hypothesis that H3.1 acts as the canonical histone that is incorporated during DNA replication, whereas H3.3 acts as the replacement histone that can be incorporated outside of S-phase during chromatin disrupting processes like transcription.
Project description:Nucleosomes package eukaryotic DNA and are composed of four different histone proteins, H3, H4, H2A and H2B. Histone H3 has two main variants, H3.1 and H3.3, which show different genomic localization patterns in animals. We profiled H3.1 and H3.3 variants in the genome of the plant Arabidopsis thaliana and show that the localization of these variants shows broad similarity in plants and animals, in addition to some unique features. H3.1 was enriched in silent areas of the genome including regions containing the repressive chromatin modifications H3 lysine 27 methylation, H3 lysine 9 methylation, and DNA methylation. In contrast, H3.3 was enriched in actively transcribed genes, especially peaking at the 3’ end of genes, and correlated with histone modifications associated with gene activation such as histone H3 lysine 4 methylation, and H2B ubiquitylation, as well as by RNA Pol II occupancy. Surprisingly, both H3.1 and H3.3 were enriched on defined origins of replication, as was overall nucleosome density, suggesting a novel characteristic of plant origins. Our results are broadly consistent with the hypothesis that H3.1 acts as the canonical histone that is incorporated during DNA replication, whereas H3.3 acts as the replacement histone that can be incorporated outside of S-phase during chromatin disrupting processes like transcription. ChIP-seq - 4 samples: 2 experiment and 2 controls RNA-seq - 1 sample
Project description:Histone acetylation and methylation regulate gene expression in eukaryotes, but their effects on the transcriptome of a multicellular organism and on the transcriptomic divergence between species are still poorly understood. Here we present the first genome-wide 1-bp resolution maps of histone acetylation, histone methylation and core histone in Arabidopsis thaliana and a comprehensive analysis of these maps and gene expression data in A. thaliana, A. arenosa and allotetraploids. H3K9 acetylation (H3K9ac) and H3K4 trimethylation (H3K4me3) are correlated, and their high densities near transcriptional start sites determine constitutive expression of genes involved in translation. In contrast, broad distributions of these modifications toward coding regions determine expression variation, especially in genes involved in photosynthesis, carbohydrate metabolism, and defense responses. A dispersed distribution of H3K27me3 and depletion of H3K9ac and H3K4me3 are associated with developmentally repressed genes. Finally, genes affected by histone deacetylase mutation and species divergence tend to show high expression variation. In conclusion, changes in histone acetylation and methylation modulate developmental and environmental gene expression variation within and between species. ChIP-Seq: Identification of distribution of H3K9ac, H3K4me3 and H3 in Arabidopsis thaliana leaf. Expression: Gene expression in the histone deacetylase 1 mutant was generated using t-DNA insertion. mRNA expressions in leaf and flower of the AtHD1 mutant were compared with those of the wild type plants. We conducted 8 replicates of dual-channel microarrays, including 4 biological replicates and individual dye swaps.
Project description:Histone 3 lysine 4 and histone 3 lysine 9 methylation in wild type and ddm1 Arabidopsis thaliana seedlings. The purpose of the chromatin immunoprecipitation/microarray (ChIP/chip) experiment is to determine which regions of a genome are enriched for a particular histone modification in a single Arabidopsis thanliana genotype. Chromatin immunoprecipitation with antibodies raised against dimethyl histone-H3 lysine-9 (H3mK9) or dimethyl histone-H3 lysine-4 (H3mK4) is performed on a selected genotype. This purified DNA from each immunoprecipiation (mH3K9, mH3K4, no antibody control) is used for random amplification to increase the quantity of DNA for microarray hybridization. The amplified DNA from each experimental sample is then labeled with Cy5 and hybridized against total input DNA from the corresponding genotype, labeled in Cy3. In a single hybridization, the total input DNA serves as a baseline and is compared to the immunoprecipitated samples. Ratios of normalized signal intensities were calculated to identify enrichment of a particular sequence after immunoprecipitation, in comparison to the total input DNA. Dye swap analysis is carried out to take account of experimental variation by repeating the hybridization with identical samples labeled with Cy3 and Cy5, respectively. This SuperSeries is composed of the SubSeries listed below.