Project description:State-of-the-art algorithms for m6A detection and quantification via nanopore direct RNA sequencing have been continuously developed, little is known about their capacities and limitations, which makes a comprehensive assessment in urgent need. Therefore, we performed comprehensive benchmarking of 10 computational tools relying on current-based and base-calling “errors” strategies for m6A detection by nanopore sequencing.
Project description:Whole-genome bisulfite sequencing (WGBS) is currently the gold standard for DNA methylation (5-methylcytosine, 5mC) profiling, however the destructive nature of sodium bisulfite results in DNA fragmentation and subsequent biases in sequencing data. Such issues have led to the development of bisulfite-free methods for 5mC detection. Nanopore sequencing is a long read non-destructive approach that directly analyzes DNA and RNA fragments in real time. Recently, computational tools have been developed that enable base-resolution detection of 5mC from Oxford Nanopore sequencing data. In this chapter we provide a detailed protocol for preparation, sequencing, read assembly and analysis of genome-wide 5mC using Nanopore sequencing technologies.
Project description:5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are modified versions of cytosine in DNA with roles in regulating gene expression. Using whole genomic DNA from mouse cerebellum, we have benchmarked 5mC and 5hmC detection by Oxford Nanopore Technologies sequencing against other standard techniques. In addition, we assessed the ability of duplex base-calling to study strand asymmetric modification. Nanopore detection of 5mC and 5hmC is accurate relative to compared techniques and opens new means of studying these modifications. Strand asymmetric modification is widespread across the genome but reduced at imprinting control regions and CTCF binding sites in mouse cerebellum. This study demonstrates the unique ability of nanopore sequencing to improve the resolution and detail of cytosine modification mapping.
Project description:The replication of eukaryotic genomes is highly stochastic, making it difficult to determine the replication dynamics of individual molecules with existing methods. We now report a sequencing method for the measurement of replication fork movement on single molecules by Detecting Nucleotide Analogue signal currents on extremely long nanopore traces (D‑NAscent). Using this method, we detect BrdU incorporated by Saccharomyces cerevisiae to reveal, at a genomic scale and on single molecules, the DNA sequences replicated during a pulse labelling period. Under conditions of limiting BrdU concentration, D-NAscent detects the differences in BrdU incorporation frequency across individual molecules to reveal the location of active replication origins, fork direction, termination sites, and fork pausing/stalling events. We used sequencing reads of 20-160 kb, to generate the first whole genome single-molecule map of DNA replication dynamics and discover a new class of low frequency stochastic origins in budding yeast.
Project description:Chemically modified analogs of GalNAc, termed GalNAz or GalNAzMe, were incorporated in secreted glycoproteins. The compounds contain bioorthogonal, clickable functional groups that allowed for enrichment using biotin. Chemical glycoproteomics was performed after on-bead digestion and cleavage of glycopeptides from the solid support.
Project description:5-Ethynyl-2’-deoxyuridine (EdU) is one of the several thymidine analogs that are used in labeling DNA in cells and in DNA combing (DNA fiber analysis) to study DNA replication1-5. We wished to use these analogs to investigate the repair complex (DNA-protein) of nucleotide excision repair. UV irradiated human cell lines were incubated with EdU, BrdU, IdU, CldU, F-ara-EdU or AmdU to incorporate these analogs into the 26-27 nucleotide long excision repair products. Unexpectedly, we found that EdU even in the absence of DNA damage was released in the form of 26-27nt-long oligomers. We conclude that EdU is incorporated into replicating DNA and is recognized as damage by the nucleotide excision repair system and removed from the genome followed by repair synthesis and re-incorporation into DNA, thus creating futile cycle that leads to cell death. This property of EdU, which was not seen with any of the other thymidine analogs, may be taken advantage of in treating cancer, in particular brain cancers because EdU crosses blood-brain barrier.
Project description:Sequencing was performed to assess the ability of Nanopore direct cDNA and native RNA sequencing to characterise human transcriptomes. Total RNA was extracted from either HAP1 or HEK293 cells, and the polyA+ fraction isolated using oligodT dynabeads. Libraries were prepared using Oxford Nanopore Technologies (ONT) kits according to manufacturers instructions. Samples were then sequenced on ONT R9.4 flow cells to generate fast5 raw reads in the ONT MinKNOW software. Fast5 reads were then base-called using the ONT Albacore software to generate Fastq reads.
Project description:Tuberous sclerosis complex (TSC) is a relatively common autosomal dominant disorder characterized by multiple dysplastic organ lesions and neuropsychiatric symptoms, caused by loss-of-function mutation of either TSC1 or TSC2. Target-capture full-length double-stranded cDNA sequencing using long-read sequencer Nanopore (Nanopore Long-read Target Sequencing) revealed that the various kinds of the TSC1 and TSC2 full-length transcripts and the novel intron retention transcripts of TSC2 in TSC patient. Our results indicate that the Nanopore Long-read Target Sequencing is useful for the detection of mutations and confers information on the full-length alternative splicing transcripts for the genetic diagnosis.
Project description:We present scNanoATAC-seq (Single-cell Assay for Transposase Accessible Chromatin by Oxford Nanopore Technologies Sequencing), an effective method for simultaneous detection of chromatin accessibility and genetic variation. Long fragments (about 4-5Kb) of single-cell ATAC-seq library were enriched and sequenced by Oxford Nanopore Technologies platform. Ends of long ATAC-seq fragments are regarded as chromatin accessibility signal in downstream analysis.