From crop improvement to breeding healthier livestock to modeling human disease, scientists are using PacBio Sequencing to advance understanding of plant and animal genomes. In this article, we look at four examples of plant and animal genome references improved or made possible with SMRT Sequencing, including an early example of transcriptome sequencing of a chicken for improved annotation. These examples highlight insights gained with SMRT Sequencing that are missed with short-read data, such as complex regions or novel genes.
Trichoplusiani derived cell lines are commonly used to enable recombinant protein expression via baculovirus infection to generate materials approved for clinical use and in clinical trials. In order to develop systems biology and genome engineering tools to improve protein expression in this host, we performed de novo genome assembly of the Trichoplusiani-derived cell line Tni-FNL.By integration of PacBio single-molecule sequencing, Bionano optical mapping, and 10X Genomics linked-reads data, we have produced a draft genome assembly of Tni-FNL.Our assembly contains 280 scaffolds, with a N50 scaffold size of 2.3 Mb and a total length of 359 Mb. Annotation of the Tni-FNL…
Allen Van Deynze from UC Davis presents the genome sequencing and assembly project for spinach, an organism of 980 Mb. Results indicate a high-accuracy assembly with significantly higher N50 contig length than a previous short-read assembly. The PacBio assembly has allowed for filling gaps in the prior assembly.
Michael Schatz from Cold Spring Harbor Laboratory talks about using SMRT Sequencing to generate the world’s best crop genome assembly, discovering thousands of gene elements that had never been seen before. He also reports on how long reads made it possible to interrogate a highly complex breast cancer cell line that was too challenging to sequence with previous platforms.
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.
Michael Schatz of Cold Spring Harbor Laboratory and Johns Hopkins University discusses the challenges in detecting structural variations (SVs) in high throughput sequencing data, especially more complex SVs such as a duplication nested within an inversion. To overcome these challenges, Dr. Schatz and his team have been applying long-read sequencing to analyze SVs in a range of samples from small microbial genomes, through mid-sized plant and animal genomes, to large mammalian genomes. The increased read lengths, which currently average over 10kbp and some approach 100kbp, make it possible to span more complex SVs and accurately assess SVs in repetitive regions,…
This seminar features great hands-on information and best practices for analyzing SMRT Sequencing data for eukaryotic genome assembly. Michael Schatz provides an overview of the assembly tools, provides recommendations for when to use each one, and discusses the challenges of short-read assemblies. James Gurtowski gives an in-depth overview of hybrid assemblies methods, where short read data are used used to correct errors in longer reads. Finally, Sergey Koren presents on chromosome-scale assembly, including the MinHash Alignment Process (MHAP) he developed to dramatically reduce the computational processing power required for genome assemblies.
At AGBT 2017, Mike Schatz from Johns Hopkins University and Cold Spring Harbor Laboratory presented data from sequencing, assembling, and analyzing personalized, phased diploid genomes with either Illumina, 10x Genomics, and PacBio SMRT Sequencing. Compared to the short-read-based methods, PacBio data assembled in large, complete contigs and contained the broadest range of structural variants with the best resolution. Plus: unexpected translocation findings with SMRT Sequencing, validated in follow-up studies.
SMRT Sequencing is a DNA sequencing technology characterized by long read lengths and high consensus accuracy, regardless of the sequence complexity or GC content of the DNA sample. These characteristics can be harnessed to address medically relevant genes, mRNA transcripts, and other genomic features that are otherwise difficult or impossible to resolve. I will describe examples for such new clinical research in diverse areas, including full-length gene sequencing with allelic haplotype phasing, gene/pseudogene discrimination, sequencing extreme DNA contexts, high-resolution pharmacogenomics, biomarker discovery, structural variant resolution, full-length mRNA isoform cataloging, and direct methylation detection.
Recent improvements in sequencing chemistry and instrument performance combine to create a new PacBio data type, Single Molecule High-Fidelity reads (HiFi reads). Increased read length and improvement in library construction enables average read lengths of 10-20 kb with average sequence identity greater than 99% from raw single molecule reads. The resulting reads have the accuracy comparable to short read NGS but with 50-100 times longer read length. Here we benchmark the performance of this data type by sequencing and genotyping the Genome in a Bottle (GIAB) HG0002 human reference sample from the National Institute of Standards and Technology (NIST). We…
AGBT 2013 Presentation Slides: Cold Spring Harbor Laboratory’s Michael Schatz presented strategies for de novo assembly of crop genomes with PacBio technolgy.
Single Molecule, Real-Time (SMRT) Sequencing holds promise for addressing new frontiers in large genome complexities, such as long, highly repetitive, low-complexity regions and duplication events, and differentiating between transcript isoforms that are difficult to resolve with short-read technologies. We present solutions available for both reference genome improvement (>100 MB) and transcriptome research to best leverage long reads that have exceeded 20 Kb in length. Benefits for these applications are further realized with consistent use of size-selection of input sample using the BluePippin™ device from Sage Science. Highlights from our genome assembly projects using the latest P5-C3 chemistry on model organisms…
Single Molecule, Real-Time (SMRT) Sequencing provides efficient, streamlined solutions to address new frontiers in plant genomes and transcriptomes. Inherent challenges presented by highly repetitive, low-complexity regions and duplication events are directly addressed with multi- kilobase read lengths exceeding 8.5 kb on average, with many exceeding 20 kb. Differentiating between transcript isoforms that are difficult to resolve with short-read technologies is also now possible. We present solutions available for both reference genome and transcriptome research that best leverage long reads in several plant projects including algae, Arabidopsis, rice, and spinach using only the PacBio platform. Benefits for these applications are further…
AGBT 2015 Workshop Presentation Slides: Dick McCombie from Cold Spring Harbor Laboratory (CSHL) described the use of SMRT Sequencing to analyze a breast cancer cell line with complex genomic events. Still ongoing, the project has already uncovered structural variants missed by other sequencers.
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…