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),…
PacBio HiFi reads provide both long read lengths (up to 25 kb) and high accuracy (>99.9%) to quickly and affordably generate contiguous, complete, and correct de novo genome assemblies of even the most complex genomes.
The newer hierarchical genome assembly process (HGAP) performs de novo assembly using data from a single PacBio long insert library. To assess the benefits of this method, DNA from several Salmonella enterica serovars was isolated from a pure culture. Genome sequencing was performed using Pacific Biosciences RS sequencing technology. The HGAP process enabled us to close sixteen Salmonella subsp. enterica genomes and their associated mobile elements: The ten serotypes include: Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) S. Bareilly, S. Heidelberg, S. Cubana, S. Javiana and S. Typhimurium, S. Newport, S. Montevideo, S. Agona, and S. Tennessee. In addition,…
Single Molecule, Real-Time (SMRT) Sequencing holds promise for addressing new frontiers to understand molecular mechanisms in evolution and gain insight into adaptive strategies. With read lengths exceeding 10 kb, we are able to sequence high-quality, closed microbial genomes with associated plasmids, and investigate large genome complexities, such as long, highly repetitive, low-complexity regions and multiple tandem-duplication events. Improved genome quality, observed at 99.9999% (QV60) consensus accuracy, and significant reduction of gap regions in reference genomes (up to and beyond 50%) allow researchers to better understand coding sequences with high confidence, investigate potential regulatory mechanisms in noncoding regions, and make inferences…
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.
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…
MHC class I and II genes are critically monitored by high-resolution sequencing for organ transplant decisions due to their role in GVHD. Their direct or linkage-based causal association, have increased their prominence as targets for drug sensitivity, autoimmune, cancer and infectious disease research. Monitoring HLA genes can however be tricky due to their highly polymorphic nature. Allele-level resolution is thus strongly preferred. However, most studies were historically focused on peptide binding domains of the HLA genes, due to technological challenges. As a result knowledge about the functional role of polymorphisms outside of exons 2 and 3 of HLA genes was…
The Genome in a Bottle Consortium is developing the reference materials, reference methods , and reference data n
We have produced an updated annotation of the Norway spruce genome on the basis of an in siliconormalised set of RNA-Seq data obtained from 1,529 samples and comprising 15.5 billion paired-end Illumina HiSeq reads complemented by 18Mbp of PacBio cDNA data (3.2M sequences). In addition to augmenting and refining the previous protein coding gene annotation, here we focus on the addition of long intergenic non-coding RNA (lincRNA) and micro RNA (miRNA) genes. In addition to non-coding loci, our analyses also identified protein coding genes that had been missed by the initial genome annotation and enabled us to update the annotation…
Target enrichment capture methods allow scientists to rapidly interrogate important genomic regions of interest for variant discovery, including SNPs, gene isoforms, and structural variation. Custom targeted sequencing panels are important for characterizing heterogeneous, complex diseases and uncovering the genetic basis of inherited traits with more uniform coverage when compared to PCR-based strategies. With the increasing availability of high-quality reference genomes, customized gene panels are readily designed with high specificity to capture genomic regions of interest, thus enabling scientists to expand their research scope from a single individual to larger cohort studies or population-wide investigations. Coupled with PacBio® long-read sequencing, these…
Alzheimer’s disease (AD) is a devastating neurodegenerative disease that is genetically complex. Although great progress has been made in identifying fully penetrant mutations in genes such as APP, PSEN1 and PSEN2 that cause early-onset AD, these still represent a very small percentage of AD cases. Large-scale, genome-wide association studies (GWAS) have identified at least 20 additional genetic risk loci for the more common form of late-onset AD. However, the identified SNPs are typically not the actual risk variants, but are in linkage disequilibrium with the presumed causative variant (Van Cauwenberghe C, et al., The genetic landscape of Alzheimer disease: clinical…
While genome assembly projects have been successful in many haploid and inbred species, the assembly of non-inbred or rearranged heterozygous genomes remains a major challenge. To address this challenge, we introduce the open-source FALCON and FALCON-Unzip algorithms (https://github.com/PacificBiosciences/FALCON/) to assemble long-read sequencing data into highly accurate, contiguous, and correctly phased diploid genomes. We generate new reference sequences for heterozygous samples including an F1 hybrid of Arabidopsis thaliana, the widely cultivated Vitis vinifera cv. Cabernet Sauvignon, and the coral fungus Clavicorona pyxidata, samples that have challenged short-read assembly approaches. The FALCON-based assemblies are substantially more contiguous and complete than alternate short-…
Bipolar disorder (BD) is a phenotypically and genetically complex and debilitating neurological disorder that affects 1% of the worldwide population. There is compelling evidence from family, twin and adoption studies supporting the involvement of a genetic predisposition in BD with estimated heritability up to ~ 80%. The risk in first-degree relatives is ten times higher than in the general population. Linkage and association studies have implicated multiple putative chromosomal loci for BP susceptibility, however no disease genes have been identified to date.
Alzheimer’s disease (AD) is a devastating neurodegenerative disease that is genetically complex. Although great progress has been made in identifying fully penetrant mutations in genes such as APP, PSEN1 and PSEN2 that cause early-onset AD, these still represent a very small percentage of AD cases. Large-scale, genome-wide association studies (GWAS) have identified at least 20 additional genetic risk loci for the more common form of late-onset AD. However, the identified SNPs are typically not the actual causal variants, but are in linkage disequilibrium with the presumed causative variant (Van Cauwenberghe C, et al., The genetic landscape of Alzheimer disease: clinical…
Over the past decades neurological disorders have been extensively studied producing a large number of candidate genomic regions and candidate genes. The SNPs identified in these studies rarely represent the true disease-related functional variants. However, more recently a shift in focus from SNPs to larger structural variants has yielded breakthroughs in our understanding of neurological disorders.Here we have developed candidate gene screening methods that combine enrichment of long DNA fragments with long-read sequencing that is optimized for structural variation discovery. We have also developed a novel, amplification-free enrichment technique using the CRISPR/Cas9 system to target genomic regions.We sequenced gDNA and…