Explore how long-read sequencing enables solving of rare and mendelian diseases.
At DuPont Pioneer, DNA sequencing is paramount for R&D to reveal the genetic basis for traits of interest in commercial crops such as maize, soybean, sorghum, sunflower, alfalfa, canola, wheat, rice, and others. They cannot afford to wait the years it has historically taken for high-quality reference genomes to be produced. Nor can they rely on a single reference to represent the genetic diversity in its germplasm.
The bacteria living on and within us can impact health, disease, and even our behavior, but there is still much to learn about the breadth of their effects. The torrent of new discoveries unleashed by high-throughput sequencing has captured the imagination of scientists and the public alike. Scientists at Second Genome are hoping to apply these insights to improve human health, leveraging their bioinformatics expertise to mine bacterial communities for potential therapeutics. Recently they teamed up with scientists at PacBio to explore how long-read sequencing might supplement their short-read-based pipeline for gene discovery, using an environmental sample as a test…
Discover the benefits of HiFi reads and learn how highly accurate long-read sequencing provides a single technology solution across a range of applications.
In higher eukaryotic organisms, the majority of multi-exon genes are alternatively spliced. Different mRNA isoforms from the same gene can produce proteins that have distinct properties such as structure, function, or subcellular localization. Thus, the importance of understanding the full complement of transcript isoforms with potential phenotypic impact cannot be underscored. While microarrays and other NGS-based methods have become useful for studying transcriptomes, these technologies yield short, fragmented transcripts that remain a challenge for accurate, complete reconstruction of splice variants. The Iso-Seq protocol developed at PacBio offers the only solution for direct sequencing of full-length, single-molecule cDNA sequences to survey…
In higher eukaryotic organisms, the majority of multi-exon genes are alternatively spliced. Different mRNA isoforms from the same gene can produce proteins that have distinct properties and functions. Thus, the importance of understanding the full complement of transcript isoforms with potential phenotypic impact cannot be understated. While microarrays and other NGS-based methods have become useful for studying transcriptomes, these technologies yield short, fragmented transcripts that remain a challenge for accurate, complete reconstruction of splice variants. The Iso-Seq protocol developed at PacBio offers the only solution for direct sequencing of full-length, single-molecule cDNA sequences to survey transcriptome isoform diversity useful for…
The protein coding potential of most plant and animal genomes is dramatically increased via alternative splicing. Identification and annotation of expressed mRNA isoforms is critical to the understanding of these complex organisms. While microarrays and other NGS-based methods have become useful for studying transcriptomes, these technologies yield short, fragmented transcripts that remain a challenge for accurate, complete reconstruction of splice variants. The Iso-Seq protocol developed at PacBio offers the only solution for direct sequencing of full-length, single-molecule cDNA sequences to survey transcriptome isoform diversity useful for gene discovery and annotation. Knowledge of the complete isoform repertoire is also key for…
A single gene may encode a surprising number of proteins, each with a distinct biological function. This is especially true in complex eukaryotes. Short- read RNA sequencing (RNA-seq) works by physically shearing transcript isoforms into smaller pieces and bioinformatically reassembling them, leaving opportunity for misassembly or incomplete capture of the full diversity of isoforms from genes of interest. The PacBio Isoform Sequencing (Iso-Seq™) method employs long reads to sequence transcript isoforms from the 5’ end to their poly-A tails, eliminating the need for transcript reconstruction and inference. These long reads result in complete, unambiguous information about alternatively spliced exons, transcriptional…
Background: Long-read sequencing presents several potential advantages for providing more complete gene profiling of metagenomic samples. Long reads can capture multiple genes in a single read, and longer reads typically result in assemblies with better contiguity, especially for higher abundance organisms. However, a major challenge with using long reads has been the higher cost per base, which may lead to insufficient coverage of low-abundance species. Additionally, lower single-pass accuracy can make gene discovery for low-abundance organisms difficult. Methods: To evaluate the pros and cons of long reads for metagenomics, we directly compared PacBio and Illumina sequencing on a soil-derived sample,…
Recent work comparing metagenomic sequencing methods indicates that a comprehensive picture of the taxonomic and functional diversity of complex communities will be difficult to achieve with short-read technology alone. While the lower cost of short reads has enabled greater sequencing depth, the greater contiguity of long-read assemblies and lack of GC bias in SMRT Sequencing has enabled better gene finding. However, since long-read assembly requires high coverage for error correction, the benefits of unbiased coverage have in the past been lost for low abundance species. SMRT Sequencing performance improvements and the introduction of the Sequel II System has enabled a…
Recent work comparing metagenomic sequencing methods indicates that a comprehensive picture of the taxonomic and functional diversity of complex communities will be difficult to achieve with one sequencing technology alone. While the lower cost of short reads has enabled greater sequencing depth, the greater contiguity of long-read assemblies and lack of GC bias in SMRT Sequencing has enabled better gene finding. However, since long-read assembly typically requires high coverage for error correction, these benefits have in the past been lost for low-abundance species. The introduction of the Sequel II System has enabled a new, higher throughput, assembly-optional data type that…
Structural variants (SVs, differences >50 base pairs) account for most of the base pairs that differ between two human genomes, and are known to cause over 1,000 genetic disorders including ALS, schizophrenia, and hereditary cancer. Yet, SVs remain overlooked in human genetic research studies due to the limited power of short-read sequencing methods (exome and whole genome sequencing) to resolve large variants, which often involve repetitive DNA. Recent advances in long-read sequencing have made it possible to detect the over 20,000 SVs that are now known to exist in a human genome. Corresponding advances in long-read SV calling algorithms have…
In this presentation, Elizabeth Tseng explains how PacBio’s full-length RNA Sequencing using the Iso-Seq method can characterize full-length transcripts without the need for computational transcript assembly. The Iso-Seq method is fully supported bioinformatically through PacBio’s SMRT Analysis software that outputs high-quality, full-length transcript sequences that can be used for genome annotation and novel gene discovery. Elizabeth shows that the highly accurate reads can be used to discover allelic-specific isoform expressions in transcriptome data.
In this PacBio User Group Meeting presentation, PacBio scientist Meredith Ashby shared several examples of analysis — from full-length 16S sequencing to shotgun sequencing — showing how SMRT Sequencing enables accurate representation for metagenomics and microbiome characterization, in some cases even without fully assembling genomes. New updates will provide users with a dedicated microbial assembly pipeline, optimized for all classes of bacteria, as well as increased multiplexing on the Sequel II System, now with 48 validated barcoded adapters. That throughput could reduce the cost of microbial analysis substantially.
To start Day 1 of the PacBio User Group Meeting, Jonas Korlach, PacBio CSO, provides an update on the latest releases and performance metrics for the Sequel II System. The longest reads generated on this system with the SMRT Cell 8M now go beyond 175,000 bases, while maintaining extremely high accuracy. HiFi mode, for example, uses circular consensus sequencing to achieve accuracy of Q40 or even Q50.