Advances in Single Molecule, Real-Time (SMRT) Sequencing

PacBio’s single-molecule real-time (SMRT) sequencing technology offers important advantages over the short-read DNA sequencing technologies that currently dominate the market. This includes exceptionally long read lengths (20 kb or more), unparalleled consensus accuracy, and the ability to sequence native, non-amplified DNA molecules. From fungi to insects to humans, long reads are now used to create highly accurate reference genomes by de novo assembly of genomic DNA and to obtain a comprehensive view of transcriptomes through the sequencing of full-length cDNAs. Besides reducing biases, sequencing native DNA also permits the direct measurement of DNA base modifications. Therefore, SMRT sequencing has become an attractive technology in many fields, such as agriculture, basic science, and medical research. The boundaries of SMRT sequencing are continuously being pushed by developments in bioinformatics and sample preparation. This book contains a collection of articles showcasing the latest developments and the breadth of applications enabled by SMRT sequencing technology

Whole-Genome Sequence of Serratia liquefaciens HUMV-21, a Cytotoxic, Quorum-Sensing, and Biofilm-Producing Clinical Isolate

A clinical isolate of Serratia liquefaciens (strain HUMV-21) was obtained from a skin ulcer of an adult patient. We report here its complete genome assembly using PacBio single-molecule real-time (SMRT) sequencing, which resulted in a single circular chromosome with 5.3 Mb. About 5,844 protein-coding genes are predicted from this assembly

SMRT sequencing data for Garcinia mangostana L. variety Mesta

The “Queen of Fruits” mangosteen (Garcinia mangostana L.) produces commercially important fruits with desirable taste of flesh and pericarp rich in xanthones with medicinal properties. To date, only limited knowledge is available on the cytogenetics and genome sequences of a common variety of mangosteen (Abu Bakar et al., 2016 [1]). Here, we report the first single-molecule real-time (SMRT) sequencing data from whole genome sequencing of mangosteen of Mesta variety. Raw reads of the SMRT sequencing project can be obtained from SRA database with the accession numbers SRX2718652 until SRX2718659

Genome sequence of Salarchaeum sp. Strain JOR-1, an extremely halophilic archaeon from the Dead Sea

An extremely halophilic archaeon, Salarchaeum sp. strain JOR-1, was isolated from the east coast of the Dead Sea, Kingdom of Jordan, and sequenced using single-molecule real-time (SMRT) sequencing. The GC-rich 2.5-Mbp genome was composed of a circular chromosome and a megaplasmid. The genome contained 2,633 genes and was incorporated into HaloWeb.Fil: Anton, Brian P.. New England Biolabs; Estados UnidosFil: DasSarma, Priya. University of Maryland; Estados UnidosFil: Martínez, Fabiana Lilian. University of Maryland; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto Nacional de Investigaciones para las Industrias Químicas; ArgentinaFil: DasSarma, Satyajit L.. University of Maryland; Estados UnidosFil: Madadha, Mohammad Al. University of Jordan; Jordania. University of Maryland; Estados UnidosFil: Roberts, Richard J.. New England Biolabs; Estados UnidosFil: DasSarma, Shiladitya. University of Maryland; Estados Unido

Single Molecule Approaches to Mapping DNA Replication Origins

DNA replication is a fundamental process that is primarily regulated at the initiation step. In higher eukaryotes, the location and properties of replication origins are not well understood. Existing genome-wide approaches to map origins—such as nascent strand abundance mapping, Okazaki fragment mapping, or chromatin immunoprecipitation-based assays—average the behavior of a population of cells. However, due to cell-to-cell variability in origin usage, single molecule techniques are necessary to investigate the actual behavior of a cell. Here, I investigate the feasibility of using three single molecule, genome-wide technologies to map origins of replication. The Pacific Biosciences Single Molecule Real-Time (SMRT) sequencing technology, the BioNano Genomics Irys optical mapping technology, and the Oxford Nanopore Technologies MinION nanopore sequencing technology are promising approaches that can advance our understanding of DNA replication in higher eukaryotes

Accelerated cloning of a potato late blight–resistance gene using RenSeq and SMRT sequencing

Global yields of potato and tomato crops are reduced owing to potato late blight disease, which is caused by Phytophthora infestans. Although most commercial potato varieties are susceptible to blight, wild potato relatives are not and are therefore a potential source of Resistance to P. infestans (Rpi) genes. Resistance breeding has exploited Rpi genes from closely related tuber-bearing potato relatives, but is laborious and slow 1–3. Here we report that the wild, diploid non-tuber-bearing Solanum americanum harbors multiple Rpi genes. We combine R gene sequence capture (RenSeq4) with single-molecule real-time SMRT sequencing (SMRT RenSeq) to clone Rpi-amr3i . This technology should enable de novo assembly of complete nucleotide-binding, leucine-rich repeat receptor (NLR) genes, their regulatory elements and complex multi-NLR loci from uncharacterized germplasm. SMRT RenSEQ can be applied to rapidly clone multiple R genes for engineering pathogen-resistant crops

Strain-level resolution and pneumococcal carriage dynamics by single-molecule real-time (SMRT) sequencing of the plyNCR marker: a longitudinal study in Swiss infants

BACKGROUND Pneumococcal carriage has often been studied from a serotype perspective; however, little is known about the strain-specific carriage and inter-strain interactions. Here, we examined the strain-level carriage and co-colonization dynamics of Streptococcus pneumoniae in a Swiss birth cohort by PacBio single-molecule real-time (SMRT) sequencing of the plyNCR marker. METHODS A total of 872 nasal swab (NS) samples were included from 47 healthy infants during the first year of life. Pneumococcal carriage was determined based on the quantitative real-time polymerase chain reaction (qPCR) targeting the lytA gene. The plyNCR marker was amplified from 214 samples having lytA-based carriage for pneumococcal strain resolution. Amplicons were sequenced using SMRT technology, and sequences were analyzed with the DADA2 pipeline. In addition, pneumococcal serotypes were determined using conventional, multiplex PCR (cPCR). RESULTS PCR-based plyNCR amplification demonstrated a 94.2% sensitivity and 100% specificity for Streptococcus pneumoniae if compared to lytA qPCR. The overall carriage prevalence was 63.8%, and pneumococcal co-colonization (≥ 2 plyNCR amplicon sequence variants (ASVs)) was detected in 38/213 (17.8%) sequenced samples with the relative proportion of the least abundant strain(s) ranging from 1.1 to 48.8% (median, 17.2%; IQR, 5.8-33.4%). The median age to first acquisition was 147 days, and having ≥ 2 siblings increased the risk of acquisition. CONCLUSION The plyNCR amplicon sequencing is species-specific and enables pneumococcal strain resolution. We therefore recommend its application for longitudinal strain-level carriage studies of Streptococcus pneumoniae. Video Abstract

Strain-level resolution and pneumococcal carriage dynamics by single-molecule real-time (SMRT) sequencing of the plyNCR marker: a longitudinal study in Swiss infants.

BACKGROUND Pneumococcal carriage has often been studied from a serotype perspective; however, little is known about the strain-specific carriage and inter-strain interactions. Here, we examined the strain-level carriage and co-colonization dynamics of Streptococcus pneumoniae in a Swiss birth cohort by PacBio single-molecule real-time (SMRT) sequencing of the plyNCR marker. METHODS A total of 872 nasal swab (NS) samples were included from 47 healthy infants during the first year of life. Pneumococcal carriage was determined based on the quantitative real-time polymerase chain reaction (qPCR) targeting the lytA gene. The plyNCR marker was amplified from 214 samples having lytA-based carriage for pneumococcal strain resolution. Amplicons were sequenced using SMRT technology, and sequences were analyzed with the DADA2 pipeline. In addition, pneumococcal serotypes were determined using conventional, multiplex PCR (cPCR). RESULTS PCR-based plyNCR amplification demonstrated a 94.2% sensitivity and 100% specificity for Streptococcus pneumoniae if compared to lytA qPCR. The overall carriage prevalence was 63.8%, and pneumococcal co-colonization (≥ 2 plyNCR amplicon sequence variants (ASVs)) was detected in 38/213 (17.8%) sequenced samples with the relative proportion of the least abundant strain(s) ranging from 1.1 to 48.8% (median, 17.2%; IQR, 5.8-33.4%). The median age to first acquisition was 147 days, and having ≥ 2 siblings increased the risk of acquisition. CONCLUSION The plyNCR amplicon sequencing is species-specific and enables pneumococcal strain resolution. We therefore recommend its application for longitudinal strain-level carriage studies of Streptococcus pneumoniae. Video Abstract

Discovery and genotyping of structural variation from long-read haploid genome sequence data

In an effort to more fully understand the full spectrum of human genetic variation, we generated deep single-molecule, real-time (SMRT) sequencing data from two haploid human genomes. By using an assembly-based approach (SMRT-SV), we systematically assessed each genome independently for structural variants (SVs) and indels resolving the sequence structure of 461,553 genetic variants from 2 bp to 28 kbp in length. We find that &gt;89% of these variants have been missed as part of analysis of the 1000 Genomes Project even after adjusting for more common variants (MAF &gt; 1%). We estimate that this theoretical human diploid differs by as much as ∼16 Mbp with respect to the human reference, with long-read sequencing data providing a fivefold increase in sensitivity for genetic variants ranging in size from 7 bp to 1 kbp compared with short-read sequence data. Although a large fraction of genetic variants were not detected by short-read approaches, once the alternate allele is sequence-resolved, we show that 61% of SVs can be genotyped in short-read sequence data sets with high accuracy. Uncoupling discovery from genotyping thus allows for the majority of this missed common variation to be genotyped in the human population. Interestingly, when we repeat SV detection on a pseudodiploid genome constructed in silico by merging the two haploids, we find that ∼59% of the heterozygous SVs are no longer detected by SMRT-SV. These results indicate that haploid resolution of long-read sequencing data will significantly increase sensitivity of SV detection.</jats:p