With Single Molecule, Real-Time (SMRT) Sequencing and the Sequel Systems, you can easily and affordably sequence complete transcript isoforms in genes of interest or across the entire transcriptome. The Iso-Seq method allows users to generate full-length cDNA sequences up to 10 kb in length — with no assembly required — to confidently characterize full-length transcript isoforms.
One of the major applications of DNA sequencing technology is to bring together information that is distant in sequence space so that understanding genome structure and function becomes easier on a large scale. The Single Molecule Real Time (SMRT) Sequencing platform provides direct sequencing data that can span several thousand bases to tens of thousands of bases in a high-throughput fashion. In contrast to solving genomic puzzles by patching together smaller piece of information, long sequence reads can decrease potential computation complexity by reducing combinatorial factors significantly. We demonstrate algorithmic approaches to construct accurate consensus when the differences between reads…
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…
PacBio 2014 User Group Meeting Presentation Slides: Anne Deslattes Mays of Georgetown University discussed how PacBio provided the necessary full-length isoform information to allow characterization of isoform distribution by sub-cell population.
Second-generation sequencing has brought about tremendous insights into the genetic underpinnings of biology. However, there are many functionally important and medically relevant regions of genomes that are currently difficult or impossible to sequence, resulting in incomplete and fragmented views of genomes. Two main causes are (i) limitations to read DNA of extreme sequence content (GC-rich or AT-rich regions, low complexity sequence contexts) and (ii) insufficient read lengths which leave various forms of structural variation unresolved and result in mapping ambiguities.
The goat (Capra hircus) remains an important livestock species due to the species’ ability to forage and provide milk, meat and wool in arid environments. The current goat reference assembly and annotation borrows heavily from other loosely related livestock species, such as cattle, and may not reflect the unique structural and functional characteristics of the species. We present preliminary data from a new de novo reference assembly for goat that primarily utilizes 38 million PacBio P5-C3 reads generated from an inbred San Clemente goat. This assembly consists of only 5,902 contigs with a contig N50 size of 2.56 megabases which…
For comprehensive metabolic reconstructions and a resulting understanding of the pathways leading to natural products, it is desirable to obtain complete information about the genetic blueprint of the organisms used. Traditional Sanger and next-generation, short-read sequencing technologies have shortcomings with respect to read lengths and DNA-sequence context bias, leading to fragmented and incomplete genome information. The development of long-read, single molecule, real-time (SMRT) DNA sequencing from Pacific Biosciences, with >10,000 bp average read lengths and a lack of sequence context bias, now allows for the generation of complete genomes in a fully automated workflow. In addition to the genome sequence,…
While advances in RNA sequencing methods have accelerated our understanding of the human transcriptome, isoform discovery remains a challenge because short read lengths require complicated assembly algorithms to infer the contiguity of full-length transcripts. With PacBio’s long reads, one can now sequence full-length transcript isoforms up to 10 kb. The PacBio Iso- Seq protocol produces reads that originate from independent observations of single molecules, meaning no assembly is needed. Here, we sequenced the transcriptome of the human MCF-7 breast cancer cell line using the Clontech SMARTer® cDNA preparation kit and the PacBio RS II. Using PacBio Iso-Seq bioinformatics software, we…
There are many sequencing-based approaches to understanding complex metagenomic communities spanning targeted amplification to whole-sample shotgun sequencing. While targeted approaches provide valuable data at low sequencing depth, they are limited by primer design and PCR amplification. Whole-sample shotgun experiments generally use short-read, second-generation sequencing, which results in data processing difficulties. For example, reads less than 1 kb in length will likely not cover a complete gene or region of interest, and will require assembly. This not only introduces the possibility of incorrectly combining sequence from different community members, it requires a high depth of coverage. As such, rare community members…
2015 SMRT Informatics Developers Conference Presentation Slides: Ali Bashir of Mount Sinai School of Medicine discussed methods for characterizing structural variation in human genomes across a variety of coverage levels.
There are many sequencing-based approaches to understanding complex metagenomic communities, spanning targeted amplification to whole-sample shotgun sequencing. While targeted approaches provide valuable data at low sequencing depth, they are limited by primer design and PCR amplification. Whole-sample shotgun experiments require a high depth of coverage. As such, rare community members may not be represented in the resulting assembly. Circular-consensus, Single Molecule, Real-Time (SMRT) Sequencing reads in the 1-2 kb range, with >99% consensus accuracy, can be efficiently generated for low amounts of input DNA, e.g. as little as 10 ng of input DNA sequenced in 4 SMRT Cells can generate…
We have developed several candidate gene screening applications for both Neuromuscular and Neurological disorders. The power behind these applications comes from the use of long-read sequencing. It allows us to access previously unresolvable and even unsequencable genomic regions. SMRT Sequencing offers uniform coverage, a lack of sequence context bias, and very high accuracy. In addition, it is also possible to directly detect epigenetic signatures and characterize full-length gene transcripts through assembly-free isoform sequencing. In addition to calling the bases, SMRT Sequencing uses the kinetic information from each nucleotide to distinguish between modified and native bases.
The killer-cell immunoglobulin-like receptor (KIR) gene family are involved in immune modulation during viral infection, autoimmune disease and in allogeneic stem cell transplantation. Most KIR gene diversity studies and their impact on the transplant outcome is performed by gene absence/presence assays. However, it is well known that KIR gene allelic variations have biological significance. Allele level typing of KIR genes has been very challenging until recently due to the homologous nature of those genes and very long intronic sequences. SMRT (Single Molecule Real-Time) Sequencing generates average long reads of 10 to 15 kb and allows us to obtain in-phase long…
Next-generation sequencing has become a useful tool for studying transcriptomes. However, these methods typically rely on sequencing short fragments of cDNA, then attempting to assemble the pieces into full-length transcripts. Here, we describe a method that uses PacBio long reads to sequence full-length cDNAs from individual transcriptomes and metatranscriptome samples. We have adapted the PacBio Iso-Seq protocol for use with prokaryotic samples by incorporating RNA polyadenylation and rRNA-depletion steps. In conjunction with SMRT Sequencing, which has average readlengths of 10-15 kb, we are able to sequence entire transcripts, including polycistronic RNAs, in a single read. Here, we show full-length bacterial…