The study of genomics has revolutionized our understanding of science, but the field of transcriptomics grew with the need to explore the functional impacts of genetic variation. While different tissues in an organism may share the same genomic DNA, they can differ greatly in what regions are transcribed into RNA and in their patterns of RNA processing. By reviewing the history of transcriptomics, we can see the advantages of RNA sequencing using a full-length transcript approach become clearer.
Discover how HiFi reads enable every aspect of viral research, from understanding viral genomes to the host immune response.
Mike Snyder from Stanford University has published recent papers in Nature Biotechnology and PNAS using SMRT Sequencing for transcriptome analysis and demonstrated that long reads enable full coverage of RNA molecules. He discusses that work and his views on long-read sequencing and transcriptomics in this podcast.
Grant Cramer from the University of Nevada, Reno, and Dario Cantu from the Univeristy of Callifornia, Davis, discuss past challenges with sequencing Clone 8 of Cabernet Sauvignon (Vitis vinifera). An assembly of the genome was attempted with approximately 110x Illumina reads and 5x PacBio reads. The PacBio SMRT Sequencing read made major improvements in the assembly compared with the results of Illumina reads only. However, the assembly results were still unsatisfactory, so an additional 100-fold SMRT Sequencing coverage had been generated. An update on the current sequencing results and status of the assembly are presented.
In this PacBio User Group Meeting presentation, Ana Conesa Cegarra from the University of Florida spoke about Iso-Seq analysis tools developed by her group, which created the popular SQANTI tools for Iso-Seq data QC. They’re also working on IsoAnnot to perform functional annotation at isoform resolution; validation has already been done on various species. Currently it’s a set of scripts, but her team is working to produce a more user-friendly version. Finally, tappAS is for functional diversity analysis and for prioritizing genes for validation.
In this PacBio User Group Meeting presentation, Nic Wheeler of University of Wisconsin-Madison, speaks about RNA sequencing for filarial nematodes associated with understudied tropical diseases. His team used Iso-Seq analysis to improve gene models and achieve better transcriptome coverage for these worms, which typically have poorly annotated and fragmented genome assemblies. While getting enough RNA to study is a technical challenge, the group still managed to generate full-length isoforms, many of which were novel or contained novel junctions.
Highly accurate long reads, known as HiFi reads, are a new tool in scientists’ sequencing toolbox. Hear PacBio users share how they are using HiFi reads to explore the genomes, transcriptomes, metagenomes and the benefits HiFi reads provide for their addressing critical life science questions.
Accurate sequencing data is key for University of Florida scientist Ana Conesa. She is using PacBio HiFi reads from the Sequel II System to identity alternative isoforms and determine the functional impact of different isoform expression in her transcriptome research.
In this SMRT Leiden 2020 Online Virtual Event presentation Pedro Oliveira of Mount Sinai shares his research on Clostridioides – a leading cause of nosocomial-acquired diarrhea and colitis across the developed world. In this study, Oliveira and coworkers performed the first comprehensive DNA methylome analysis of 36 human C. difficile isolates from a hospital setting using SMRT Sequencing and comparative epigenomics.
In this SMRT Leiden 2020 Online Virtual Event presentation, Ana Conesa of the University of Florida shares her work on the latest updates to the Funciitonal Iso-Annot software, that includes SQANTI, IsoAnnot and tappAS. SQANTI includes new features such as assessment of TSS and TTS sites and sequencing depth. SQANTI3 includes direct annotation of IsoAnnot annotation labels and direct compatibility with tappAS for differential splicing analysis and functional annotation of long reads data.
The widespread occurrence of repetitive stretches of DNA in genomes of organisms across the tree of life imposes fundamental challenges for sequencing, genome assembly, and automated annotation of genes and proteins. This multi-level problem can lead to errors in genome and protein databases that are often not recognized or acknowledged. As a consequence, end users working with sequences with repetitive regions are faced with ‘ready-to-use’ deposited data whose trustworthiness is difficult to determine, let alone to quantify. Here, we provide a review of the problems associated with tandem repeat sequences that originate from different stages during the sequencing-assembly-annotation-deposition workflow, and…
The zebra mussel, Dreissena polymorpha, continues to spread from its native range in Eurasia to Europe and North America, causing billions of dollars in damage and dramatically altering invaded aquatic ecosystems. Despite these impacts, there are few genomic resources for Dreissena or related bivalves, with nearly 450 million years of divergence between zebra mussels and its closest sequenced relative. Although the D. polymorpha genome is highly repetitive, we have used a combination of long-read sequencing and Hi-C-based scaffolding to generate the highest quality molluscan assembly to date. Through comparative analysis and transcriptomics experiments we have gained insights into processes that…
Arthrinium phaeospermum (Corda) M.B. Ellis is a globally distributed pathogenic fungus with a wide host range; its hosts include not only plants, but also humans and animals. This study aimed to develop genomic resources for A. phaeospermum to provide solid data and a theoretical basis for further studies of its pathogenesis, transcriptomics, proteomics, metabolomics and RNA genomics. The genome was obtained from the mycelia of the strain AP-Z13 using a combination of analyses with the high-throughput Illumina HiSeq 4000 system and PacBio RSII LongRead sequencing platform. Functional annotation was performed by BLASTing protein sequences against those in different publicly available…
Over the past decade, RNA sequencing (RNA-seq) has become an indispensable tool for transcriptome-wide analysis of differential gene expression and differential splicing of mRNAs. However, as next-generation sequencing technologies have developed, so too has RNA-seq. Now, RNA-seq methods are available for studying many different aspects of RNA biology, including single-cell gene expression, translation (the translatome) and RNA structure (the structurome). Exciting new applications are being explored, such as spatial transcriptomics (spatialomics). Together with new long-read and direct RNA-seq technologies and better computational tools for data analysis, innovations in RNA-seq are contributing to a fuller understanding of RNA biology, from questions…
Long-read RNA sequencing (RNA-seq) is promising to transcriptomics studies, however, the alignment of the reads is still a fundamental but non-trivial task due to the sequencing errors and complicated gene structures. We propose deSALT, a tailored two-pass long RNA-seq read alignment approach, which constructs graph-based alignment skeletons to sensitively infer exons, and use them to generate spliced reference sequence to produce refined alignments. deSALT addresses several difficult issues, such as small exons, serious sequencing errors and consensus spliced alignment. Benchmarks demonstrate that this approach has a better ability to produce high-quality full-length alignments, which has enormous potentials to transcriptomics studies.