Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1033613 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR26583000.fastq.gz | Fastqsanger.gz | |||
| SRR26582976.fastq.gz | Fastqsanger.gz | |||
| SRR26582977.fastq.gz | Fastqsanger.gz | |||
| SRR26582978.fastq.gz | Fastqsanger.gz | |||
| SRR26582979.fastq.gz | Fastqsanger.gz |
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Project description:Background: Cell free DNA (cfDNA) in plasma has received increasing attention and has been studied in a broad range of clinical conditions implicating inflammation, cancer, and aging. However, few studies have focused on mitochondrial DNA (mtDNA) in the cell free form. This study characterized the size distribution and sequence characteristics of plasma cell free mtDNA (cf mtDNA) in humans.Methods and Results: We optimized DNA isolation and next-generation sequencing library preparation protocols to better retain short DNA fragments from plasma, and applied these optimized methods to plasma samples from patients with sepsis. After massive parallel sequencing, we verified that our methods can retain substantially shorter DNA fragments than the standard isolation method, resulting in an average of 11.5 fold increase in short DNA fragments yield (DNA < 100bp). We report that cf mtDNA in plasma is highly enriched in short-size cfDNA (30 ~ 60 bp), which is much shorter than the value previously reported (~140 bp). Motivated by this unique size distribution, we size-selected short cfDNA fragments from the sequencing library, which further increased the mtDNA recovery rate by an average of 10.4 fold. Using this approach we detected mixtures of different mtDNA sequences, termed heteroplasmy, in plasma from 3 patients. In one patient who previously received bone marrow transplantation, different minor allele frequencies were observed between plasma and white blood cells (WBC) at heteroplasmic mtDNA sites, consistent with mixed-tissue origin for plasma DNA.Conclusion: mtDNA in plasma exists as very short fragments that exhibit mtDNA heteroplasmy distribution differences from that found in a single organ/tissue. This study is the first report of genome wide identification of mtDNA heteroplasmy in human plasma. Our optimized method can be used to investigate the potential utility of cf mtDNA fragments and heteroplasmy as biomarkers in various diseases.
2016-05-07 | GSE81178 | GEO
Project description:It has been established that short inverted repeats (SIRs) trigger base substitution mutagenesis in human cells. However, how the replication machinery deals with this structured DNA is unknown. We have previously reported that in human cell-free extracts, DNA primer extension using a structured single-stranded DNA template is transiently blocked at DNA hairpins [1](Schmutz et al., 2007). Here, we report the proteomic analysis of proteins bound to the DNA template providing evidence that proteins of the NHEJ pathway, particularly the DNA-PK complex (composed of DNA-PKcs and the Ku70/Ku80 dimer) recognize structured single-stranded DNA. DNA-PKcs inhibition results in the mobilization on the template DNA of the DNA-PK complex, along with other proteins acting downstream in the NHEJ pathway, especially the XRCC4-DNA Ligase 4 complex and the recently identified cofactor PAXX. The retention of NHEJ factors to the template DNA in the absence of DNA-PKcs activity correlates with additional halts of primer extension, suggesting that NHEJ proteins may hinder the progression of the DNA synthesis at these sites. Conversely, hijacking of the DNA-PK complex by double-stranded oligos (dsO) results in a large removal of the pausing sites and an elevated DNA extension efficiency. Overall these results raise the possibility that, upon binding to DNA hairpins formed onto ssDNA during fork progression, the DNA-PK complex may play some role in replication fork dynamics in vivo, role that is however not related to repair of double-strand breaks.
2020-02-04 | PXD011156 | Pride
Project description:Cytosine deaminases have important uses in the detection of epigenetic modifications and in genome editing. However, the range of applications of deaminases is limited by their substrate preference. To expand the toolkit of deaminases, we developed an in-vitro approach that bypasses a major hurdle with their severe toxicity in expression hosts. We screened 175 putative cytosine deaminases, primarily from bacteria, and found enzymes with strong activity on double- and single-stranded DNA in various sequence contexts, including some without any sequence constraints. We also found enzymes that do not deaminate modified cytosines. The remarkable diversity of cytosine deaminases opens new avenues for biotechnological and medical applications. As a demonstration, we developed a single-enzyme methylation sequencing (SEM-seq) method for 5-methylcytosine detection using a novel non-specific, modification-sensitive double-stranded DNA deaminase, MsddA. SEM-seq generated accurate base-resolution maps of 5-methylcytosine in human genome samples including cell free DNA and samples of 10 pg DNA, equivalent to single cell input. This simple and efficient protocol has the potential to allow high-throughput epigenome profiling of scarce biological material.
2023-10-05 | GSE233932 | GEO
Project description:Mapping of double-stranded DNA breaks in Trypanosoma brucei using BLISS
| PRJEB61713 | ENA
Project description:Whole-genome bisulfite sequencing (BS-Seq) measures cytosine methylation changes at single-base resolution and can be used to profile cell-free DNA (cfDNA). In plasma, ultrashort single-stranded cfDNA (uscfDNA, ~50 nt) has been identified together with 167 bp double-stranded mononucleosomal cell-free DNA (mncfDNA). However, the methylation profile of uscfDNA has not been described. Conventional BS-Seq workflows may not be helpful because bisulfite conversion degrades larger DNA into smaller fragments, leading to erroneous categorization as uscfDNA. We describe the “5mCAdpBS-Seq” workflow in which pre-methylated 5mC (5-methylcytosine) single-stranded adapters are ligated to heat-denatured cfDNA before bisulfite conversion. This method retains only DNA fragments that are unaltered by bisulfite treatment, resulting in less biased uscfDNA methylation analysis. Using 5mCAdpBS-Seq, uscfDNA had lower levels of DNA methylation (~15%) and was enriched in promoters and CpG islands. Hypomethylated uscfDNA fragments were enriched in upstream transcription start sites (TSSs), and the intensity of enrichment positively affected gene expression of hemopoietic cells. Using tissue-of-origin deconvolution, we inferred that uscfDNA is derived primarily from eosinophils, neutrophils, and monocytes. As proof-of-principle, we show that characteristics of the methylation profile of uscfDNA can distinguish non-small cell lung carcinoma from non-cancer samples. The 5mCAdpBS-Seq workflow is recommended for any cfDNA methylation-based investigations.
2024-03-28 | GSE252088 | GEO
Project description:In this study, a single- and a double-stranded library preparation approach was evaluated with respect to their technical biases when applied on cfDNA from plasma and urine. This study thus outlines potential limitations of double-stranded library preparation for methylation analysis of cfDNA especially for urinary cfDNA. While the double-stranded method allows jagged end analysis in addition to TOO analysis, it leads to significant methylation bias in urinary cfDNA, which single-stranded methods can overcome.
| EGAS00001007314 | EGA
Project description:Single Centre, open label assignment phase II clinical study.
To evaluate the effect of oral 200mg Methylene Blue tablets (administered 8x25mg) prior to endoscopy on double stranded DNA breaks in colonic biopsy samples assessed by histone gamma H2AX analysis, compared to control biopsies.
| 2178654 | ecrin-mdr-crc
Project description:Here we developed a new approach to sepsis diagnosis that integrates host transcriptional profiling with metagenomic broad-range pathogen detection from cell-free plasma RNA and DNA.
2022-08-03 | GSE189401 | GEO