Biology subjects

Naarmann-de Vries, I. S.

Publications and source records attributed to Naarmann-de Vries, I. S..

5 recordsLinked to original sources

bioRxiv2025

QutRNA2: Robust tRNA modification discovery from Nanopore direct tRNA sequencing

Transfer RNAs (tRNAs) are essential for protein synthesis and are extensively modified to ensure their structure and function. Direct RNA sequencing with Oxford Nanopore Technologies enables positional modification analysis but is challenged by tRNAs short length, redundancy, and dense modifications. We present QutRNA2, a scalable workflow featuring GPU-accelerated local alignment, statistical filtering, pairwise error profile comparison, and customizable visualization. Achieving up to 25-fold speed gains over CPU methods, QutRNA2 identifies enzyme-dependent modifications in nuclear- and mitochondrial-encoded tRNAs, demonstrated in human and mouse samples. This open-source solution provides a comprehensive, multiplexing-compatible framework for tRNA analysis, addressing a key gap in current tools.

bioinformatics↗

bioRxiv2025

WarpDemuX-tRNA: barcode multiplexing for nanopore tRNA sequencing

Transfer RNA (tRNA) plays an essential role in protein translation and tRNA modifications are important to their function. Recently, nanopore direct RNA sequencing (dRNA-seq) has shown promising results in the detection of complex tRNA modifications. However, its wider adoption in the tRNA field has been limited by a lack of (de)multiplexing solutions. Here, we present WarpDemuX-tRNA: an extension to the WarpDemuX method specifically optimized for multiplexed nanopore tRNA sequencing. Using consensus-based signal analysis using (soft) Dynamic Time Warping and barycenter averaging, our approach improves barcode feature generation and achieves more robust barcode identification. WarpDemuX-tRNA outperforms the original method and achieves 99% precision and 95% recovery for four barcodes, while reducing computational complexity and runtime to six minutes per one million reads. WarpDemuX-tRNA is an open-source and free-to-use solution to high-throughput nanopore tRNA sequencing, facilitating more accessible, cost-effective and high-throughput studies of tRNA modifications and their regulatory mechanisms.

bioinformatics↗

bioRxiv2025

The two-step purification method ViREn identifies a single NSUN6-mediated 5-methylcytosine modification promoting dengue virus RNA genome turnover

Chemical modifications on cellular and viral RNAs are new layers of post-transcriptional regulation of cellular processes including RNA stability and translation. Although advances in analytical methods have improved detection sensitivity, the precise mapping of RNA modifications at single-base resolution remains challenging. Especially for low abundant viral RNAs extracted from infected cells, requirements for sensitivity and purity limit accuracy and reproducibility. Here we report the two-step method ViREn for the enrichment of the genomic RNA (gRNA) of dengue virus (DENV), a positive-sense single-stranded RNA virus. This approach enabled the preparation of gRNA with significantly increased purity and led to the identification of a high-confidence 5-methylcytosine (m5C) site in DENV gRNA, orthogonally validated by Illumina-based bisulfite sequencing and direct RNA sequencing by Nanopore Oxford Technologies. Strikingly, this m5C modification was exclusively detected in gRNA extracted from infected cells but not in gRNA extracted from viral particles. We identified NSUN6 as the host methyltransferase catalyzing this modification and demonstrated a role for m5C in regulating DENV gRNA turnover. ViREn thus enables the mapping of m5C on low abundance viral gRNA with unprecedented precision and sensitivity and facilitates mechanistic studies into the role of RNA modification in virus replication.

biochemistry↗

bioRxiv2022

Adaptive Sampling as tool for Nanopore direct RNA-sequencing

ONT long-read sequencing provides real-time monitoring and controlling of individual nanopores. Adaptive sampling enriches or depletes specific sequences in Nanopore DNA sequencing, but was not applicable to direct sequencing of RNA so far. Here, we identify essential parameter settings for direct RNA sequencing (DRS). We demonstrate the superior performance of depletion over enrichment and show that adaptive sampling efficiently depletes specific transcripts in transcriptome-wide sequencing applications. Specifically, we applied our adaptive sampling approach to polyA+ RNA samples from human cardiomyocytes and mouse whole heart tissue. Herein, we show more than 2.5-fold depletion of highly abundant mitochondrial-encoded transcripts that in normal sequencing account for up to 40% of sequenced bases in heart tissue samples.

bioinformatics↗

bioRxiv2021

Deep assessment of human disease-associated ribosomal RNA modifications using Nanopore direct RNA sequencing

The catalytically active component of ribosomes, rRNA, is long studied and heavily modified. However, little is known about functional and pathological consequences of changes in human rRNA modification status. Direct RNA sequencing on the Nanopore platform enables the direct assessment of rRNA modifications. We established a targeted Nanopore direct rRNA sequencing approach and applied it to CRISPR-Cas9 engineered HCT116 cells, lacking specific enzymatic activities required to establish defined rRNA base modifications. We analyzed these sequencing data along with wild type samples and in vitro transcribed reference sequences to specifically detect changes in modification status. We show for the first time that direct RNA-sequencing is feasible on smaller, i.e. Flongle, flow cells. Our targeted approach reduces RNA input requirements, making it accessible to the analysis of limited samples such as patient derived material. The analysis of rRNA modifications during cardiomyocyte differentiation of human induced pluripotent stem cells, and of heart biopsies from cardiomyopathy patients revealed altered modifications of specific sites, among them pseudouridines, 2-O-methylation of riboses and acetylation of cytidines. Targeted direct rRNA-seq analysis with JACUSA2 opens up the possibility to analyze dynamic changes in rRNA modifications in a wide range of biological and clinical samples.

molecular biology↗