Project description:We identified exosomal miRNA biomarkers for pancreatic cancer diagnostics by isolating exosomes using a recently developed magnetic nanopore isolation technology and small RNA sequencing.
Project description:<p>Despite the nuclear localization of the m6A machinery, the genomes of multiple exclusively-cytoplasmic RNA viruses, such as chikungunya (CHIKV) and dengue (DENV), are reported to be extensively m6A-modified. However, these findings are mostly based on m6A-seq, an antibody-dependent technique with a high rate of false positives. Here, we addressed the presence of m6A in CHIKV and DENV RNAs. For this, we combined m6A-seq and the antibody-independent SELECT and nanopore direct RNA sequencing techniques with functional, molecular, and mutagenesis studies. Following this comprehensive analysis, we found no evidence of m6A modification in CHIKV or DENV transcripts. Furthermore, depletion of key components of the host m6A machinery did not affect CHIKV or DENV infection. Moreover, CHIKV or DENV infection had no effect on the m6A machinery’s localization. Our results challenge the prevailing notion that m6A modification is a general feature of cytoplasmic RNA viruses and underscore the importance of validating RNA modifications with orthogonal approaches.</p>
Project description:Viral genome sequencing is critical for understanding viral biology, identifying strain mutations, and managing public health during pandemics. Although sequencing technologies have progressed over the years in terms of throughput and cost, a portable platform that integrates sample processing, library preparation, and sequencing remains critical for point-of-care viral sequencing that combats viral outbreaks in the field. In here, we demonstrate a semi-automated, field-deployable microreactor system to produce nanopore sequencing libraries from viral samples. The system integrates isothermal amplification, purification, and enzymatic processing within a closed-channel format, minimizing contamination risk and operational complexity. Using Senecavirus A (SVA) as a surrogate for high-consequence pathogens, we demonstrate the system’s ability to prepare sequencing libraries targeting three dispersed genomic regions comprising ~16% of the viral genome and identify single nucleotide variations with high confidence. Together with a portable nanopore sequencer, this microreactor offers a robust solution for decentralized genomic surveillance and rapid diagnostics in resource-limited or outbreak-prone environments.
Project description:<p>Despite improved diagnostics, pulmonary pathogens in immunocompromised children frequently evade detection, leading to significant mortality. In this study, we performed RNA and DNA-based metagenomic next generation sequencing (mNGS) on 41 lower respiratory samples collected from 34 children. We identified a rich cross-domain pulmonary microbiome containing bacteria, fungi, RNA viruses, and DNA viruses in each patient. Potentially pathogenic bacteria were ubiquitous among samples but could be distinguished as possible causes of disease by parsing for outlier organisms. Potential pathogens were detected in half of samples previously negative by clinical diagnostics. Ongoing investigation is needed to determine the pathogenic significance of outlier microbes in the lungs of immunocompromised children with pulmonary disease. Metatranscriptomic (RNA) sequencing libraries are reported in the manuscript and are included for this release.</p>
Project description:Transfer RNAs are the fundamental adapter molecules of protein synthesis and the most abundant and heterogeneous class of noncoding RNA molecules in cells. The study of tRNA repertoires remains challenging, complicated by the presence of dozens of post transcriptional modifications. Nanopore sequencing is an emerging technology with promise for both tRNA sequencing and the detection of RNA modifications; however, such studies have been limited by the throughput and accuracy of direct RNA sequencing methods. Moreover, detection of the complete set of tRNA modifications by nanopore sequencing remains challenging. Here we show that recent updates to nanopore direct RNA sequencing chemistry (RNA004) combined with our own optimizations to tRNA sequencing protocols and analysis workflows enable high throughput coverage of tRNA molecules and characterization of nanopore signals produced by 43 distinct RNA modifications. We share best practices and protocols for nanopore sequencing of tRNA and further report successful detection of low abundance mitochondrial and viral tRNAs, providing proof of concept for use of nanopore sequencing to study tRNA populations in the context of infection and organelle biology. This work provides a roadmap to guide future efforts towards de novo detection of RNA modifications across multiple organisms using nanopore sequencing.
Project description:We used endpoint PCR to verify the presence of a new subgenomic RNA in SARS-CoV-2 (termed N.iORF3) and verify using nanopore sequencing that this is expressed via a newly evolved transcription regulatory sequence (TRS). We further show that this encodes a truncated C-terminal portion of Nucleocapsid, which is an antagonist of type I interferon production. Using reverse genetics-derived viruses we show N.iORF3 contributes to viral fitness during infection and observe distinct phenotypes when the Nucleocapsid coding sequence is mutated compared to when the TRS alone is ablated.
Project description:We sequenced DNA from a bulk of Col x Ler F2 hybrid plants (WT and recq4) using Nanopore long-read sequencing and identified crossover sites with COmapper. For nanopore sequencing of gDNA from 1,000 pooled seedlings, 10-day-old seedlings were ground in liquid nitrogen using a mortar and pestle. The ground tissue was resuspended in four volumes of CTAB buffer (1% [w/v] CTAB, 50 mM Tris-HCl pH 8.0, 0.7 M NaCl, 10 mM EDTA) and incubated at 65°C for 30 min. Following chloroform extraction, isopropanol precipitation and removal of RNAs as above, the gDNA pellet was resuspended in 150 μl TE (10 mM Tris-HCl pH 8.0, 0.1 mM EDTA) buffer and gDNA was quantified using a Qubit dsDNA Broad Range assay kit (Thermo Fisher, Q32853). Nine micrograms of gDNA from pollen or seedlings was used to construct a nanopore long-read sequencing library using a Ligation Sequencing Kit V14 (Nanopore, SQK-LSK114). The libraries were sequenced using a PromethION platform (BGI, Hong Kong).