Project description:Alternative splicing contributes to transcriptomic complexity and plays a role in the regulation of cellular identity and function, but the correct assembly of transcripts of complex loci as well as their quantification based on short-read sequencing is non-trivial. Recent long-read sequencing methods such as those from ONT and PacBio overcome these problems by potentially sequencing full transcripts. The activation of brown adipose tissue e.g., by reduced ambient temperature (cold) exposure, positively affects metabolism by increasing energy expenditure and releasing endocrine factors and has been shown to involve specific alternative splicing events. Here we assessed important features of ONT long read sequencing protocols in relation to Illumina short read sequencing: (i) Alignment characteristics to the reference genome and transcriptome, (ii) Gene and transcript detection and quantification, (iii) Detection of differential gene and transcript expression events, (iv) Transcriptome reannotation and (v) Detection of differential transcript usage events. We find that ONT long-read sequencing is advantageous in terms of transcriptome reassembly, especially when the reads are enriched for full length reads. Illumina sequencing, due to the higher number of counts available, has a higher statistical power for calling differentiall expressed/used features, whereas long-read sequencing has a lower risk of calling false positive events due to the better ability to unambiguously map reads to transcripts. Finally we describe novel transcript isoforms in cold-activated murine iBAT reassembled from ONT long reads.
Project description:MotivationDirect RNA-seq (dRNA-seq) using Oxford Nanopore Technology (ONT) has revolutionized transcript mapping by offering enhanced precision due to its long-read length. Unlike traditional techniques, dRNA-seq eliminates the need for PCR amplification, reducing the impact of GC bias, and preserving valuable base physical information, such as RNA modification and poly(A) length estimation. However, the rapid advancement of ONT devices has set higher standards for analytical software, resulting in potential challenges of software incompatibility and reduced efficiency.ResultsWe present a novel workflow, called FASTdRNA, to manipulate dRNA-seq data efficiently. This workflow comprises two modules: a data preprocessing module and a data analysis module. The preprocessing data module, dRNAmain, encompasses basecalling, mapping, and transcript counting, which are essential for subsequent analyses. The data analysis module consists of a range of downstream analyses that facilitate the estimation of poly(A) length, prediction of RNA modifications, and assessment of alternative splicing events across different conditions with duplication. The FASTdRNA workflow is designed for the Snakemake framework and can be efficiently executed locally or in the cloud. Comparative experiments have demonstrated its superior performance compared to previous methods. This innovative workflow enhances the research capabilities of dRNA-seq data analysis pipelines by optimizing existing processes and expanding the scope of analysis.Availability and implementationThe workflow is freely available at https://github.com/Tomcxf/FASTdRNA under an MIT license. Detailed install and usage guidance can be found in the GitHub repository.
Project description:Alternative splicing contributes to transcriptomic complexity and plays a role in the regulation of cellular identity and function, but the correct assembly of transcripts of complex loci as well as their quantification based on short-read sequencing is non-trivial. Recent long-read sequencing methods such as those from ONT and PacBio overcome these problems by potentially sequencing full transcripts. The activation of brown adipose tissue e.g., by reduced ambient temperature (cold) exposure, positively affects metabolism by increasing energy expenditure and releasing endocrine factors and has been shown to involve specific alternative splicing events. Here we assessed important features of ONT long read sequencing protocols in relation to Illumina short read sequencing: (i) Alignment characteristics to the reference genome and transcriptome, (ii) Gene and transcript detection and quantification, (iii) Detection of differential gene and transcript expression events, (iv) Transcriptome reannotation and (v) Detection of differential transcript usage events. We find that ONT long-read sequencing is advantageous in terms of transcriptome reassembly, especially when the reads are enriched for full length reads. Illumina sequencing, due to the higher number of counts available, has a higher statistical power for calling differentiall expressed/used features, whereas long-read sequencing has a lower risk of calling false positive events due to the better ability to unambiguously map reads to transcripts. Finally we describe novel transcript isoforms in cold-activated murine iBAT reassembled from ONT long reads.
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:Long-read RNA sequencing technologies offer unparalleled in- sights into transcriptomes by enabling full-length sequencing of RNA molecules, uncovering novel isoforms and alternative splicing events. While long-read sequencing platforms, such as Pacific Biosciences (PacBio) and Oxford Nanopore Technologies (ONT), have historically been associated with higher error rates, recent advancements in both platforms have significantly en- hanced read accuracy, broadening their applicability for tran- scriptomic studies. With the rapid evolution of sequencing protocols and bioin- formatics tools, the trade-offs between sequencing throughput, read length, accuracy, and cost present significant challenges in selecting the optimal approach. Systematic benchmarking studies that compare these options are crucial to inform fu- ture research directions. However, many existing benchmark- ing datasets with matched data across multiple platforms have limitations, including: 1) a lack of realistic biological replicates, which may restrict the generalisability of differential analysis results to real-world scenarios, and 2) the use of earlier sequenc- ing kits, which may not reflect the latest advancements in se- quencing technology, limiting their relevance for future studies that typically use newer sequencing protocols. Here we present LongBench, a comprehensive benchmarking dataset designed to fill these critical gaps. Derived from eight lung cancer cell lines with synthetic RNA spike-ins, LongBench includes bulk, single-cell, and single-nucleus RNA-seq data from three state-of-the-art long-read sequencing platforms — ONT PCR-cDNA, ONT direct RNA, PacBio Kinnex — alongside Il- lumina short-read data for robust cross-platform comparisons. The LongBench dataset is a valuable resource for benchmarking and improving sequencing protocols and bioinformatics tools. With the LongBench dataset we present a systematic evaluation of transcript capture, quantification, and differential expression analyses, examining the strengths and limitations of each se- quencing platform in various biological contexts, enabling re- searchers to make more informed decisions on platform and method selection.
Project description:Alternative splicing contributes to transcriptomic complexity and plays a role in the regulation of cellular identity and function, but the correct assembly of transcripts of complex loci as well as their quantification based on short-read sequencing is non-trivial. Recent long-read sequencing methods such as those from ONT and PacBio overcome these problems by potentially sequencing full transcripts. The activation of brown adipose tissue e.g., by reduced ambient temperature (cold) exposure, positively affects metabolism by increasing energy expenditure and releasing endocrine factors and has been shown to involve specific alternative splicing events. Here we assessed important features of ONT long read sequencing protocols in relation to Illumina short read sequencing: (i) Alignment characteristics to the reference genome and transcriptome, (ii) Gene and transcript detection and quantification, (iii) Detection of differential gene and transcript expression events, (iv) Transcriptome reannotation and (v) Detection of differential transcript usage events. We find that ONT long-read sequencing is advantageous in terms of transcriptome reassembly, especially when the reads are enriched for full length reads. Illumina sequencing, due to the higher number of counts available, has a higher statistical power for calling differentiall expressed/used features, whereas long-read sequencing has a lower risk of calling false positive events due to the better ability to unambiguously map reads to transcripts. Finally we describe novel transcript isoforms in cold-activated murine iBAT reassembled from ONT long reads.
Project description:Transcriptional profiling of breast cell lines comparing breast cell line mixed reference with individual breast cell lines. Goal was to characterize breast cell line subtypes.
Project description:Epitranscriptomics modifications constitute a gene expression checkpoint in all living organism including plants. Considering the relevance of nitrogen nutrition and metabolism for the correct plant growth and development, it can be hypothesized that epitranscriptome changes must regulate every biological process in plants including nitrogen nutrition. In the present work, the epritranscriptomics changes in maritime pine roots caused by ammonium nutrition have been monitored through direct RNA sequencing using Oxford Nanopore Technology. The main transcriptome responses to ammonium nutrition affected to transcripts involved in nitrogen and carbon metabolisms, defense response, hormone synthesis and signaling, and translation. Additionally to a global detection of epitranscriptomics marks, the m6A deposition and its dynamics have been identified, which seems to be important regulators of translation when compared with the proteomic profiles of the same samples. In this sense, the obtained results suggest that protein translation is finely regulated through the epitranscriptomics marks maybe through changes in mRNA polyA length, transcript amount and ribosome protein composition. The multiomics results in the present study suggest that the epitranscriptome must modulate the responses to development and environmental changes, including ammonium nutrition, through buffering, filtering and focusing the final products of the gene expression.