Project description:The naked mole-rat (NMR; Heterocephalus glaber) has recently gained considerable attention in the scientific community for its unique potential to unveil novel insights in the fields of medicine, biochemistry, and evolution. NMRs exhibit unique adaptations that include protracted fertility, cancer resistance, eusociality, and anoxia. This suite of adaptations is not found in other rodent species, suggesting that interrogating conserved and accelerated regions in the NMR genome will find regions of the NMR genome fundamental to their unique adaptations. However, the current NMR genome assembly has limits that make studying structural variations, heterozygosity, and non-coding adaptations challenging. We present a complete diploid naked-mole rat genome assembly by integrating long-read and 10X-linked read genome sequencing of a male NMR and its parents, and Hi-C sequencing in the NMR hypothalamus (N=2). Reads were identified as maternal, paternal or ambiguous (TrioCanu). We then polished genomes with Flye, Racon and Medaka. Assemblies were then scaffolded using the following tools in order: Scaff10X, Salsa2, 3d-DNA, Minimap2-alignment between assemblies, and the Juicebox Assembly Tools. We then subjected the assemblies to another round of polishing, including short-read polishing with Freebayes. We assembled the NMR mitochondrial genome with mitoVGP. Y chromosome contigs were identified by aligning male and female 10X linked reads to the paternal genome and finding male-biased contigs not present in the maternal genome. Contigs were assembled with publicly available male NMR Fibroblast Hi-C-seq data (SRR820318). Both assemblies have their sex chromosome haplotypes merged so that both assemblies have a high-quality X and Y chromosome. Finally, assemblies were evaluated with Quast, BUSCO, and Merqury, which all reported the base-pair quality and contiguity of both assemblies as high-quality. The assembly will next be annotated by Ensembl using public RNA-seq data from multiple tissues (SRP061363). Together, this assembly will provide a high-quality resource to the NMR and comparative genomics communities.
Project description:This study benchmarks bulk and single-cell long-read RNA sequencing technologies in a human neuronal model of Fragile X syndrome. NGN2-induced neurons were generated from patient-derived iPSCs carrying a silenced FMR1 gene (FXS line E3) and an isogenic CRISPR-corrected rescue line (IsoB11) in which FMR1 expression is restored. These conditions provide a defined system to evaluate transcript detection and quantification across sequencing platforms. Bulk and single-cell RNA-seq datasets were generated using Illumina short-read sequencing and long-read sequencing from Pacific Biosciences (PB) and Oxford Nanopore Technologies (ONT). Single-cell libraries were prepared using the 10x Genomics Chromium platform. ERCC and SIRV spike-in controls were added to bulk samples to enable benchmarking of transcript quantification accuracy. Three biological replicates were sequenced for each condition. The dataset enables cross-platform comparisons of transcript detection, quantification methods, transcript length biases, and sequencing depth requirements for long-read transcriptomic analyses.
Project description:This study benchmarks bulk and single-cell long-read RNA sequencing technologies in a human neuronal model of Fragile X syndrome. NGN2-induced neurons were generated from patient-derived iPSCs carrying a silenced FMR1 gene (FXS line E3) and an isogenic CRISPR-corrected rescue line (IsoB11) in which FMR1 expression is restored. These conditions provide a defined system to evaluate transcript detection and quantification across sequencing platforms. Bulk and single-cell RNA-seq datasets were generated using Illumina short-read sequencing and long-read sequencing from Pacific Biosciences (PB) and Oxford Nanopore Technologies (ONT). Single-cell libraries were prepared using the 10x Genomics Chromium platform. ERCC and SIRV spike-in controls were added to bulk samples to enable benchmarking of transcript quantification accuracy. Three biological replicates were sequenced for each condition. The dataset enables cross-platform comparisons of transcript detection, quantification methods, transcript length biases, and sequencing depth requirements for long-read transcriptomic analyses.
Project description:Single-cell RNA sequencing analysis has recently provided snapshots of gene expression of specific cell types and enabled cell types classification within an heterogenous population. As well as transcriptional changes, alternative splicing events and modifications of components of splicing machinery actively contributes in shaping cellular phenotype as well as ageing process and diseases occurence. Current high-throughput single-cell RNA sequencing methods may lack information on cell-specific isoform expression, missing key aspects of cell biology. In the present work we introduce a novel approach using the 10X Genomics Chromium to generate short-read (Illumina) and long-read (Pacific Biosciences Sequel II) RNA-sequencing libraries from the same single cells. This approach produced single cell parallel transcriptional and splicing profiling that demonstrates for the first time cell-type specific isoform expression and alterations at transcriptional levels associated with ageing in haematopoietic stem and progenitor cells
Project description:Background: Single-cell CRISPR screens have transformed functional genomics by enabling scalable, systematic investigation of gene function. Despite this, transcriptional complexity has largely been overlooked, with studies focusing on gene-level effects rather than isoforms. Methods capable of capturing splicing and isoform usage have emerged, including long-read sequencing and alternative library preparation strategies, but their suitability for large-scale perturbation screens remains unevaluated. Results: We compare two single-cell library preparation methods (5' 10x Genomics and Parse Biosciences Evercode) across Illumina short-read, Oxford Nanopore Technologies, and PacBio long-read sequencing, applying CRISPRi to silence three genes with distinct regulatory roles (DDX6, GEMIN5 and GFI1B) in K562 cells. While short-read methods can detect some alternative splicing events, only long-read sequencing consistently captures isoform-level changes. Although Parse Evercode provided even coverage across transcripts, we observed strong enrichment of intronic reads, limiting its utility for splicing analysis. The primary constraint of long-read approaches was depth: approximately 21 million reads are required for 80% saturation of splicing events in a single perturbation, underscoring the need for higher-throughput methods. Despite these limitations, we show that GEMIN5 perturbation produced modest differential expression but the most extensive splicing changes, an effect invisible to gene-level analysis, highlighting the importance of extending CRISPR screens to isoform-level readouts. Conclusions: We provide a practical framework for isoform-level analysis in single-cell CRISPR screens, identifying both the capabilities and current limitations of available approaches. As perturbation studies scale, long-read sequencing will be essential for comprehensive functional interpretation, capturing biology missed by gene-level analysis.
Project description:With an ability to compromise genome integrity, transposable elements (TEs) have significant associations with human diseases. Short-read sequencing has been used to study the expression of TEs; however, the highly repetitive nature of these elements makes multimapping a critical issue. Here we implement LocusMasterTE, an improved quantification method by integrating long-read sequencing. Introducing computed transcript per million(TPM) counts from long-read sequencing as prior distribution during Expectation-Maximization(EM) model in short-read TE quantification, multi-mapped reads are re-assigned to correct expression values. Based on simulated short reads, LocusMasterTE outperforms current quantitative approaches and is significantly favorable in capturing newly inserted TEs. We also verified that TEs quantified by LocusMasterTE clearly related to euchromatins and heterochromatins in cell line samples. With LocusMasterTE we anticipate that more accurate quantification can be performed, allowing novel functions of TEs to be uncovered.
Project description:The naked mole-rat (NMR; Heterocephalus glaber) has recently gained considerable attention in the scientific community for its unique potential to unveil novel insights in the fields of medicine, biochemistry, and evolution. NMRs exhibit unique adaptations that include protracted fertility, cancer resistance, eusociality, and anoxia. This suite of adaptations is not found in other rodent species, suggesting that interrogating conserved and accelerated regions in the NMR genome will find regions of the NMR genome fundamental to their unique adaptations. However, the current NMR genome assembly has limits that make studying structural variations, heterozygosity, and non-coding adaptations challenging. We present a complete diploid naked-mole rat genome assembly by integrating long-read and 10X-linked read genome sequencing of a male NMR and its parents, and Hi-C sequencing in the NMR hypothalamus (N=2). Reads were identified as maternal, paternal or ambiguous (TrioCanu). We then polished genomes with Flye, Racon and Medaka. Assemblies were then scaffolded using the following tools in order: Scaff10X, Salsa2, 3d-DNA, Minimap2-alignment between assemblies, and the Juicebox Assembly Tools. We then subjected the assemblies to another round of polishing, including short-read polishing with Freebayes. We assembled the NMR mitochondrial genome with mitoVGP. Y chromosome contigs were identified by aligning male and female 10X linked reads to the paternal genome and finding male-biased contigs not present in the maternal genome. Contigs were assembled with publicly available male NMR Fibroblast Hi-C-seq data (SRR820318). Both assemblies have their sex chromosome haplotypes merged so that both assemblies have a high-quality X and Y chromosome. Finally, assemblies were evaluated with Quast, BUSCO, and Merqury, which all reported the base-pair quality and contiguity of both assemblies as high-quality. The assembly will next be annotated by Ensembl using public RNA-seq data from multiple tissues (SRP061363). Together, this assembly will provide a high-quality resource to the NMR and comparative genomics communities.