Learn how highly accurate long-read sequencing from the Sequel IIe Systems delivers data you can trust for advanced biological insights across a range of applications.
A first look at Pacific Biosciences RS data Pacific Biosciences technology provides a fundamentally new data type that provides the potential to overcome these limitations by providing significantly longer reads (now averaging >1kb), enabling more unique seeds for reference alignment. In addition, the lack of amplification in the library construction step avoids a common source of base composition bias. With these potential advantages in mind, we here evaluate the utility of the Pacific Biosciences RS platform for human medical resequencing projects by assessing the quality of the raw sequencing data, as well as its use for SNP discovery and genotyping…
In this study we demonstrate the utility of Single-Molecule Real Time SMRT sequencing to detect variants and to recapitulate whole mitochondrial genomes in an association study of Metabolic syndrome using samples from a well-studied cohort from Micronesia. The Micronesian island of Kosrae is a rare genetic isolate that offers significant advantages for genetic studies of human disease. Kosrae suffers from one of the highest rates of MetS (41%), obesity (52%), and diabetes (17%) globally and has a homogeneous environment making this an excellent population in which to study these significant health problems. We are conducting family-based association analyses aimed at…
T-cells play a central part in the immune response in humans and related species. T-cell receptors (TCRs), heterodimers located on the T-cell surface, specifically bind foreign antigens displayed on the MHC complex of antigen-presenting cells. The wide spectrum of potential antigens is addressed by the diversity of TCRs created by V(D)J recombination. Profiling this repertoire of TCRs could be useful from, but not limited to, diagnosis, monitoring response to treatments, and examining T-cell development and diversification.
HiFi reads (>99% accurate, 15-20 kb) from the PacBio Sequel II System consistently provide complete and contiguous genome assemblies. In addition to completeness and contiguity, accuracy is of critical importance, as assembly errors complicate downstream analysis, particularly by disrupting gene frames. Metrics used to assess assembly accuracy include: 1) in-frame gene count, 2) kmer consistency, and 3) concordance to a benchmark, where discordances are interpreted as assembly errors. Genome in a Bottle (GIAB) provides a benchmark for the human genome with estimated accuracy of 99.9999% (Q60). Concordance for human HiFi assemblies exceeds Q50, which provides excellent genomes for downstream analysis,…
In this webinar, Jonas Korlach, Chief Scientific Officer, PacBio provides an overview of the features and the advantages of the new Sequel II System. Kiran Garimella, Senior Computational Scientist, Broad Institute of MIT and Harvard University, describes his work sequencing humans with HiFi reads enabling discovery of structural variants undetectable in short reads. Luke Tallon, Scientific Director, Genomics Resource Center, Institute for Genome Sciences, University of Maryland School of Medicine, covers the GRC’s work on bacterial multiplexing, 16S microbiome profiling, and shotgun metagenomics. Finally, Shane McCarthy, Senior Research Associate, University of Cambridge, focuses on the scaling and affordability of high-quality…
In this webinar, Dr. Ashby gives attendees a brief update on PacBio’s metagenomics solutions on the Sequel II System. Then, Dr. Ma, University of Maryland School of Medicine, discusses her work using long read sequencing to identify high-resolution microbial biomarkers associated with leaky gut syndrome in premature infants. Finally, Dr. Weinstock, The Jackson Laboratory, talks about the potential of highly accurate long reads to enable strain-level resolution of the human gut microbiome by resolving intraspecies variation in multiple copies of the 16S gene.
Chlorella vulgaris is a fast-growing fresh-water microalga cultivated at the industrial scale for applications ranging from food to biofuel production. To advance our understanding of its biology and to establish genetics tools for biotechnological manipulation, we sequenced the nuclear and organelle genomes of Chlorella vulgaris 211/11P by combining next generation sequencing and optical mapping of isolated DNA molecules. This hybrid approach allowed to assemble the nuclear genome in 14 pseudo-molecules with an N50 of 2.8 Mb and 98.9% of scaffolded genome. The integration of RNA-seq data obtained at two different irradiances of growth (high light-HL versus low light -LL) enabled…
Forest tree species are increasingly subject to severe mortalities from exotic pests, diseases, and invasive organisms, accelerated by climate change. Forest health issues are threatening multiple species and ecosystem sustainability globally. While sources of resistance may be available in related species, or among surviving trees, introgression of resistance genes into threatened tree species in reasonable time frames requires genome-wide breeding tools. Asian species of chestnut (Castanea spp.) are being employed as donors of disease resistance genes to restore native chestnut species in North America and Europe. To aid in the restoration of threatened chestnut species, we present the assembly of…
Haplotype-resolved genome assemblies are important for understanding how combinations of variants impact phenotypes. These assemblies can be created in various ways, such as use of tissues that contain single-haplotype (haploid) genomes, or by co-sequencing of parental genomes, but these approaches can be impractical in many situations. We present FALCON-Phase, which integrates long-read sequencing data and ultra-long-range Hi-C chromatin interaction data of a diploid individual to create high-quality, phased diploid genome assemblies. The method was evaluated by application to three datasets, including human, cattle, and zebra finch, for which high-quality, fully haplotype resolved assemblies were available for benchmarking. Phasing algorithm accuracy…
Satellite repeats are a structural component of centromeres and telomeres, and in some instances their divergence is known to drive speciation. Due to their highly repetitive nature, satellite sequences have been understudied and underrepresented in genome assemblies. To investigate their turnover in great apes, we studied satellite repeats of unit sizes up to 50?bp in human, chimpanzee, bonobo, gorilla, and Sumatran and Bornean orangutans, using unassembled short and long sequencing reads. The density of satellite repeats, as identified from accurate short reads (Illumina), varied greatly among great ape genomes. These were dominated by a handful of abundant repeated motifs, frequently…
Motivation: Third-generation sequencing technologies can sequence long reads, which is advancing the frontiers of genomics research. However, their high error rates prohibit accurate and efficient downstream analysis. This difficulty has motivated the development of many long read error correction tools, which tackle this problem through sampling redundancy and/or leveraging accurate short reads of the same biological samples. Existing studies to asses these tools use simulated data sets, and are not sufficiently comprehensive in the range of software covered or diversity of evaluation measures used. Results: In this paper, we present a categorization and review of long read error correction methods,…
Brassica napus (AACC, 2n = 38) is an important oilseed crop grown worldwide. However, little is known about the population evolution of this species, the genomic difference between its major genetic groups, such as European and Asian rapeseed, and the impacts of historical large-scale introgression events on this young tetraploid. In this study, we reported the de novo assembly of the genome sequences of an Asian rapeseed (B. napus), Ningyou 7, and its four progenitors and compared these genomes with other available genomic data from diverse European and Asian cultivars. Our results showed that Asian rapeseed originally derived from European rapeseed but subsequently…
Suppressed recombination allows divergence between homologous sex chromosomes and the functionality of their genes. Here, we reveal patterns of the earliest stages of sex-chromosome evolution in the diploid dioecious herb Mercurialis annua on the basis of cytological analysis, de novo genome assembly and annotation, genetic mapping, exome resequencing of natural populations, and transcriptome analysis. The genome assembly contained 34,105 expressed genes, of which 10,076 were assigned to linkage groups. Genetic mapping and exome resequencing of individuals across the species range both identified the largest linkage group, LG1, as the sex chromosome. Although the sex chromosomes of M. annua are karyotypically…
Chemical defense against predators is widespread in natural ecosystems. Occasionally, taxonomically distant organisms share the same defense chemical. Here, we describe an unusual tripartite marine symbiosis, in which an intracellular bacterial symbiont (“Candidatus Endobryopsis kahalalidefaciens”) uses a diverse array of biosynthetic enzymes to convert simple substrates into a library of complex molecules (the kahalalides) for chemical defense of the host, the alga Bryopsis sp., against predation. The kahalalides are subsequently hijacked by a third partner, the herbivorous mollusk Elysia rufescens, and employed similarly for defense. “Ca E. kahalalidefaciens” has lost many essential traits for free living and acts as a…