As the foundation for scientific discoveries in genetic diversity, sequencing data must be accurate and complete. With highly accurate long-read sequencing, or HiFi sequencing, there is no longer a compromise between read length and accuracy. HiFi sequencing enables some of the highest quality de novo genome assemblies available today as well as comprehensive variant detection in human samples. PacBio HiFi libraries constructed using our standard library workflows require at least 3 µg of DNA input per 1 Gb of genome length, or ~10 µg for a human sample. For some samples it is not possible to extract this amount of…
Scientists at UC Davis School of Medicine have used the PacBio RS to sequence a previously “unsequenceable” region of highly repetitive DNA on the X chromosome. Their research has provided a critical leap forward in understanding the genetic complexity of repeat expansion disorders such as Fragile X Syndrome. The new method provides a path towards the first accurate means of population screening for Fragile X Syndrome, which is the most common cause of inherited intellectual disability and the most common known genetic cause of autism.
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…
Several new high-quality human genome assemblies produce ethnicity-specific reference sequences and show how scientists can use this genetic information to improve precision medicine studies in Asian sub- populations. These projects demonstrate how long- read SMRT Sequencing provides robust detection of polymorphic structural variants in clinically relevant gene coding regions and phases variants into haplotypes.
To understand the genetic factors underlying health and disease and to address hidden heritability, scientists require a more comprehensive view of all the variations in the human genome. Single Molecule, Real-Time (SMRT) Sequencing delivers the read lengths, uniform coverage, and accuracy needed for accessing the complete size spectrum of sequence variant types — from single nucleotides to complex structural variants. PacBio’s long single-molecule reads also provide direct variant phasing information across full-length genes and chromosome haplotype blocks. With SMRT Sequencing, scientists gain new insight into the genetic basis of health and disease.
In this webinar you will hear how several researchers have overcome the challenges of sequencing organisms with small body size using the new low and ultra-low DNA input methods from PacBio. Learn about the advantages of using highly accurate long reads (HiFi reads) to sequence and de novo assemble genomes of single individuals.
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…
Isolated from Aran-Bidgol Lake in Iran, and reported here, Halorubrum ezzemoulense strain Fb21 represents the first complete genome from this archaeal species. Local recombination in this genome is in stark contrast to equidistant recombination events in bacteria. The genome’s GC bias, however, points to a genome architecture and origin that resemble those of a bacterium. Its availability, genome signatures, and frequent intragenomic recombination mean that Fb21 presents an attractive model organism for this species. Copyright © 2019 Feng et al.
Acer yangbiense is a newly described critically endangered endemic maple tree confined to Yangbi County in Yunnan Province in Southwest China. It was included in a programme for rescuing the most threatened species in China, focusing on “plant species with extremely small populations (PSESP)”.We generated 64, 94, and 110 Gb of raw DNA sequences and obtained a chromosome-level genome assembly of A. yangbiense through a combination of Pacific Biosciences Single-molecule Real-time, Illumina HiSeq X, and Hi-C mapping, respectively. The final genome assembly is ~666 Mb, with 13 chromosomes covering ~97% of the genome and scaffold N50 sizes of 45 Mb.…
In the past several years, single-molecule sequencing platforms, such as those by Pacific Biosciences and Oxford Nanopore Technologies, have become available to researchers and are currently being tested for clinical applications. They offer exceptionally long reads that permit direct sequencing through regions of the genome inaccessible or difficult to analyze by short-read platforms. This includes disease-causing long repetitive elements, extreme GC content regions, and complex gene loci. Similarly, these platforms enable structural variation characterization at previously unparalleled resolution and direct detection of epigenetic marks in native DNA. Here, we review how these technologies are opening up new clinical avenues that…
The commercial release of third-generation sequencing technologies (TGSTs), giving long and ultra-long sequencing reads, has stimulated the development of new tools for assembling highly contiguous genome sequences with unprecedented accuracy across complex repeat regions. We survey here a wide range of emerging sequencing platforms and analytical tools for de novo assembly, provide background information for each of their steps, and discuss the spectrum of available options. Our decision tree recommends workflows for the generation of a high-quality genome assembly when used in combination with the specific needs and resources of a project.Copyright © 2019 Elsevier Ltd. All rights reserved.
Current diagnostic testing for genetic disorders involves serial use of specialized assays spanning multiple technologies. In principle, genome sequencing (GS) can detect all genomic pathogenic variant types on a single platform. Here we evaluate copy-number variant (CNV) calling as part of a clinically accredited GS test.We performed analytical validation of CNV calling on 17 reference samples, compared the sensitivity of GS-based variants with those from a clinical microarray, and set a bound on precision using orthogonal technologies. We developed a protocol for family-based analysis of GS-based CNV calls, and deployed this across a clinical cohort of 79 rare and undiagnosed…
In recent genome analyses, population-specific reference panels have indicated important. However, reference panels based on short-read sequencing data do not sufficiently cover long insertions. Therefore, the nature of long insertions has not been well documented. Here, we assembled a Japanese genome using single-molecule real-time sequencing data and characterized insertions found in the assembled genome. We identified 3691 insertions ranging from 100?bps to ~10,000?bps in the assembled genome relative to the international reference sequence (GRCh38). To validate and characterize these insertions, we mapped short-reads from 1070 Japanese individuals and 728 individuals from eight other populations to insertions integrated into GRCh38. With…
In this PacBio User Group Meeting presentation, PacBio scientist Meredith Ashby shared several examples of analysis — from full-length 16S sequencing to shotgun sequencing — showing how SMRT Sequencing enables accurate representation for metagenomics and microbiome characterization, in some cases even without fully assembling genomes. New updates will provide users with a dedicated microbial assembly pipeline, optimized for all classes of bacteria, as well as increased multiplexing on the Sequel II System, now with 48 validated barcoded adapters. That throughput could reduce the cost of microbial analysis substantially.
Understanding interactions among plants and the complex communities of organisms living on, in and around them requires more than one experimental approach. A new method for de novo metagenome assembly, PacBio HiFi sequencing, has unique strengths for determining the functional capacity of metagenomes. With HiFi sequencing, the accuracy and median read length of unassembled data outperforms the quality metrics for many existing assemblies generated with other technologies, enabling cost-competitive recovery of full-length genes and operons even from rare species. When paired with the ability to close the genomes of even challenging isolates like Xanthomonas, the PacBio Sequel II System is…