Single Molecule, Real-Time (SMRT) Sequencing uses the natural process of DNA replication to sequence long fragments of native DNA. As such, starting with high-quality, high molecular weight (HMW) genomic DNA (gDNA) will result in better sequencing performance across difficult to sequence regions of the genome. To obtain the highest quality, long DNA it is important to start with sample types compatible with HMW DNA extraction methods. This technical note is intended to give general guidance on sample collection, preparation, and storage across a range of commonly encountered sample types used for SMRT Sequencing whole genome projects. It is important to…
Obtaining microbial genomes with the highest accuracy and contiguity is extremely important when exploring the functional impact of genetic and epigenetic variants on a genome-wide scale. A comprehensive view of the bacterial genome, including genes, regulatory regions, IS elements, phage integration sites, and base modifications is vital to understanding key traits such as antibiotic resistance, virulence, and metabolism. SMRT Sequencing provides complete genomes, often assembled into a single contig. Our streamlined microbial multiplexing procedure for the Sequel System, from library preparation to genome assembly, can be completed with less than 8 hours bench time. Starting with high-quality genomic DNA (gDNA),…
With Single Molecule, Real-Time (SMRT) Sequencing and the Sequel System, you can easily and cost effectively generate highly accurate long reads (HiFi reads, >99% single-molecule accuracy) from genes or regions of interest ranging in size from several hundred base pairs to 20 kb. Target all types of variation across relevant genomic regions, including low complexity regions like repeat expansions, promoters, and flanking regions of transposable elements.
Understanding the genetic basis of infectious diseases is critical to enacting effective treatments, and several large-scale sequencing initiatives are underway to collect this information. Sequencing bacterial samples is typically performed by mapping sequence reads against genomes of known reference strains. While such resequencing informs on the spectrum of single-nucleotide differences relative to the chosen reference, it can miss numerous other forms of variation known to influence pathogenicity: structural variations (duplications, inversions), acquisition of mobile elements (phages, plasmids), homonucleotide length variation causing phase variation, and epigenetic marks (methylation, phosphorothioation) that influence gene expression to switch bacteria from non- pathogenic to pathogenic…
Understanding the genetic basis of infectious diseases is critical to enacting effective treatments, and several large-scale sequencing initiatives are underway to collect this information. Sequencing bacterial samples is typically performed by mapping sequence reads against genomes of known reference strains. While such resequencing informs on the spectrum of single nucleotide differences relative to the chosen reference, it can miss numerous other forms of variation known to influence pathogenicity: structural variations (duplications, inversions), acquisition of mobile elements (phages, plasmids), homonucleotide length variation causing phase variation, and epigenetic marks (methylation, phosphorothioation) that influence gene expression to switch bacteria from non-pathogenic to pathogenic…
The three classes of genes that comprise the MHC gene family are actively involved in determining donor-recipient compatibility for organ transplant, as well as susceptibility to autoimmune diseases via cross-reacting immunization. Specifically, Class I genes HLA-A, -B, -C, and class II genes HLA-DR, -DQ and -DP are considered medically important for genetic analysis to determine histocompatibility. They are highly polymorphic and have thousands of alleles implicated in disease resistance and susceptibility. The importance of full-length HLA gene sequencing for genotyping, detection of null alleles, and phasing is now widely acknowledged. While DNA-sequencing-based HLA genotyping has become routine, only 7% of…
PacBio RS II sequencing chemistries provide read lengths beyond 20 kb with high consensus accuracy. The long read lengths of P4-C2 chemistry and demonstrated consensus accuracy of 99.999% are ideal for applications such as de novo assembly, targeted sequencing and isoform sequencing. The recently launched P5-C3 chemistry generates even longer reads with N50 often >10,000 bp, making it the best choice for scaffolding and spanning structural rearrangements. With these chemistry advances, PacBio’s read length performance is now primarily determined by the SMRTbell library itself. Size selection of a high-quality, sheared 20 kb library using the BluePippin™ System has been demonstrated…
PacBio SMRT Sequencing has the unique ability to directly detect base modifications in addition to the nucleotide sequence of DNA. Because eukaryotes use base modifications to regulate gene expression, the absence or presence of epigenetic events relative to the location of genes is critical to elucidate the function of the modification. Therefore an integrated approach that combines multiple omic-scale assays is necessary to study complex organisms. Here, we present an integrated analysis of three sequencing experiments: 1) DNA sequencing, 2) base-modification detection, and 3) Iso-seq analysis, in Neurospora crassa, a filamentous fungus that has been used to make many landmark…
Advances in RNA sequencing have accelerated our understanding of the transcriptome, however isoform discovery remains challenging due to short read lengths. The Iso-Seq Application provides a new alternative to sequence full-length cDNA libraries using long reads from the PacBio RS II. Identification of long and often rare isoforms is demonstrated with rat heart and lung RNA prepared using the Clontech® SMARTer® cDNA preparation kit, followed by agarose-gel size selection in fractions of 1-2 kb, 2-3 kb and 3-6 kb. For each tissue, 1.8 and 1.2 million reads were obtained from 32 and 26 SMRT Cells, respectively. Filtering for reads with…
Maximizing the read length of next generation sequencing (NGS) facilitates de novo genome assembly. Currently, the PacBio RS II system leads the industry with respect to maximum possible NGS read lengths. Amplicon Express specializes in preparation of high molecular weight, NGS-grade genomic DNA for a variety of applications, including next generation sequencing. This study was performed to evaluate the effects of gDNA quality on PacBio RS II read length.
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…
Since the advent of Next-Generation Sequencing (NGS), the cost of de novo genome sequencing and assembly have dropped precipitately, which has spurred interest in genome sequencing overall. Unfortunately the contiguity of the NGS assembled sequences, as well as the accuracy of these assemblies have suffered. Additionally, most NGS de novo assemblies leave large portions of genomes unresolved, and repetitive regions are often collapsed. When compared to the reference quality genome sequences produced before the NGS era, the new sequences are highly fragmented and often prove to be difficult to properly annotate. In some cases the contiguous portions are smaller than…
The majority of human genes are alternatively spliced, making it possible for most genes to generate multiple proteins. The process of alternative splicing is highly regulated in a developmental-stage and tissue-specific manner. Perturbations in the regulation of these events can lead to disease in humans. Alternative splicing has been shown to play a role in human cancer, muscular dystrophy, Alzheimer’s, and many other diseases. Understanding these diseases requires knowing the full complement of mRNA isoforms. Microarrays and high-throughput cDNA sequencing have become highly successful tools for studying transcriptomes, however these technologies only provide small fragments of transcripts and building complete…
With the introduction of P6-C4 chemistry, PacBio has made significant strides with Single Molecule, Real-Time (SMRT) Sequencing . Read lengths averaging between 10 and 15 kb can be now be achieved with extreme reads in the distribution of > 60 kb. The chemistry attains a consensus accuracy of 99.999% (QV50) at 30x coverage which coupled with an increased throughput from the PacBio RS II platform (500 Mb – 1 Gb per SMRT Cell) makes larger genome projects more tractable. These combined advancements in technology deliver results that rival the quality of Sanger “clone-by-clone” sequencing efforts; resulting in closed microbial genomes…
Human MHC class I genes HLA-A, -B, -C, and class II genes HLA-DR, -DP and -DQ, play a critical role in the immune system as major factors responsible for organ transplant rejection. The have a direct or linkage-based association with several diseases, including cancer and autoimmune diseases, and are important targets for clinical and drug sensitivity research. HLA genes are also highly polymorphic and their diversity originates from exonic combinations as well as recombination events. A large number of new alleles are expected to be encountered if these genes are sequenced through the UTRs. Thus allele-level resolution is strongly preferred…