Project description:The paired-end Illumina sequencing of total genomic DNA from Arabidopsis were performed to detect unique breakpoints consistent with rearrangements of chloroplast DNA.
Project description:We performed chloroplast ChIP-seq (cpChIP-seq) to identify the possible DNA-binding sites of mTERF5 in Arabidopsis thaliana. To this end, we generated transgenic Arabidopsis plants expressing mTERF5 carrying an HA tag under the control of the CaMV 35S promoter. Then, We used the polyclonal antibody (abcam, ab9110, lot GR304617-8 ) against HA tag which conjugated to ChIP-Grade protein A/G agarose (Thermo scientific, 26161, lot QJ223903) to perform cpChIP assay. The obtained chromatin immunoprecipitated DNA of chloroplasts were used to build DNA libaries for high-throughput sequencing. Finally, we showed that three potenssial DNA regions across the chloroplast genome compared to the control group were enriched by mTERF5.
Project description:Punctuated bursts of structural genomic variations (SVs) have been described in various organisms, but their etiology remains incompletely understood. Homologous recombination (HR) is a template-guided mechanism of repair of DNA double-strand breaks and stalled or collapsed replication forks. We recently identified a DNA break amplification and genome rearrangement pathway originating from the endonucleolytic processing of a multi-invasion (MI) DNA joint molecule formed during HR. Genome-wide sequencing approaches confirmed that multi-invasioninduced rearrangement (MIR) frequently leads to several repeat-mediated SVs and aneuploidies. Using molecular and genetic analysis, and a novel, highly sensitive proximity ligation-based assay for chromosomal rearrangement quantification, we further delineate two MIR sub-pathways. MIR1 is a universal pathway occurring in any sequence context, which generates secondary breaks and frequently leads to additional SVs. MIR2 occurs only if recombining donors exhibit substantial homology, and results in sequence insertion without additional break or SV. The most detrimental MIR1 pathway occurs late on a subset of persisting DNA joint molecules in a PCNA/Polδ- independent manner, unlike recombinational DNA synthesis. This work provides a refined mechanistic understanding of these HR-based SV formation pathways and shows that complex repeat-mediated SVs can occur without displacement DNA synthesis. Sequence signatures for inferring MIR1 from long-read data are proposed.
Project description:Chloroplasts are organelles responsible for photosynthesis. They originated form a procaryotic ancestor in the process of endosymbiosis and contain their own genomes. The chloroplast genome is packaged into a chromatin-like structure known as the nucleoid. The internal arrangement of the nucleoid, molecular mechanisms of DNA packaging and connection of the nucleoid structure to gene expression remain poorly understood. We show that Arabidopsis thaliana chloroplast nucleoids have a unique organization driven by DNA binding to the thylakoid membranes. Membrane association of specific DNA regions is correlated with high levels of transcription, high protein occupancy and reduced DNA accessibility. Genes with low levels of transcription are further away from the membranes, have lower protein occupancy and higher DNA accessibility. Gene-specific disruption of transcription in sigma factor mutants causes a corresponding reduction in membrane association, indicating that RNA polymerase activity causes DNA tethering to the membranes. We propose that transcription organizes the chloroplast nucleoid into a transcriptionally active membrane-associated core and a less active Periphery.
Project description:Chloroplasts are organelles responsible for photosynthesis. They originated form a procaryotic ancestor in the process of endosymbiosis and contain their own genomes. The chloroplast genome is packaged into a chromatin-like structure known as the nucleoid. The internal arrangement of the nucleoid, molecular mechanisms of DNA packaging and connection of the nucleoid structure to gene expression remain poorly understood. We show that Arabidopsis thaliana chloroplast nucleoids have a unique organization driven by DNA binding to the thylakoid membranes. Membrane association of specific DNA regions is correlated with high levels of transcription, high protein occupancy and reduced DNA accessibility. Genes with low levels of transcription are further away from the membranes, have lower protein occupancy and higher DNA accessibility. Gene-specific disruption of transcription in sigma factor mutants causes a corresponding reduction in membrane association, indicating that RNA polymerase activity causes DNA tethering to the membranes. We propose that transcription organizes the chloroplast nucleoid into a transcriptionally active membrane-associated core and a less active Periphery.
Project description:Chloroplasts are organelles responsible for photosynthesis. They originated form a procaryotic ancestor in the process of endosymbiosis and contain their own genomes. The chloroplast genome is packaged into a chromatin-like structure known as the nucleoid. The internal arrangement of the nucleoid, molecular mechanisms of DNA packaging and connection of the nucleoid structure to gene expression remain poorly understood. We show that Arabidopsis thaliana chloroplast nucleoids have a unique organization driven by DNA binding to the thylakoid membranes. Membrane association of specific DNA regions is correlated with high levels of transcription, high protein occupancy and reduced DNA accessibility. Genes with low levels of transcription are further away from the membranes, have lower protein occupancy and higher DNA accessibility. Gene-specific disruption of transcription in sigma factor mutants causes a corresponding reduction in membrane association, indicating that RNA polymerase activity causes DNA tethering to the membranes. We propose that transcription organizes the chloroplast nucleoid into a transcriptionally active membrane-associated core and a less active Periphery.
Project description:Chloroplasts are organelles responsible for photosynthesis. They originated form a procaryotic ancestor in the process of endosymbiosis and contain their own genomes. The chloroplast genome is packaged into a chromatin-like structure known as the nucleoid. The internal arrangement of the nucleoid, molecular mechanisms of DNA packaging and connection of the nucleoid structure to gene expression remain poorly understood. We show that Arabidopsis thaliana chloroplast nucleoids have a unique organization driven by DNA binding to the thylakoid membranes. Membrane association of specific DNA regions is correlated with high levels of transcription, high protein occupancy and reduced DNA accessibility. Genes with low levels of transcription are further away from the membranes, have lower protein occupancy and higher DNA accessibility. Gene-specific disruption of transcription in sigma factor mutants causes a corresponding reduction in membrane association, indicating that RNA polymerase activity causes DNA tethering to the membranes. We propose that transcription organizes the chloroplast nucleoid into a transcriptionally active membrane-associated core and a less active Periphery.
Project description:The experiment was conducted to examine the influence of non-chloroplast genomes rearangements on chloroplast transcription in cucumber
Project description:Punctuated bursts of structural genomic variations (SVs) have been described in various organisms, but their etiology remains incompletely understood. Homologous recombination (HR) is a template-guided mechanism of repair of DNA double-strand breaks and stalled or collapsed replication forks. We recently identified a DNA break amplification and genome rearrangement pathway originating from the endonucleolytic processing of a multi-invasion (MI) DNA joint molecule formed during HR. Genome-wide sequencing approaches confirmed that multi-invasion-induced rearrangement (MIR) frequently leads to several repeat-mediated SVs and aneuploidies. Using molecular and genetic analysis, and a novel, highly sensitive proximity ligation-based assay for chromosomal rearrangement quantification, we further delineate two MIR sub-pathways. MIR1 is a universal pathway occurring in any sequence context, which generates secondary breaks and frequently leads to additional SVs. MIR2 occurs only if recombining donors exhibit substantial homology, and results in sequence insertion without additional break or SV. The most detrimental MIR1 pathway occurs late on a subset of persisting DNA joint molecules in a PCNA/Pold-independent manner, unlike recombinational DNA synthesis. This work provides a refined mechanistic understanding of these HR-based SV formation pathways and shows that complex repeat-mediated SVs can occur without displacement DNA synthesis. Sequence signatures for inferring MIR1 from long-read data are proposed.
Project description:Epigenomics is developing a colon cancer screening assay based on differential methylation of specific CpG sites for the detection of early stage disease. A genome-wide methylation analysis and oligonucleotide array study using DNA from various stages of colon cancer and normal tissue have been completed to obtain candidate CpG markers. Based on results obtained in the above studies, Epigenomics has moved to the final stages of feasibility with a specific, highly sensitive real-time marker assay that is able to detect colon cancer DNA in blood plasma.