In this webinar, Emily Hatas of PacBio shares information about the applications and benefits of SMRT Sequencing in plant and animal biology, agriculture, and industrial research fields. This session contains…
In this presentation, Sonja Vernes of the Max Plank Institute shares her work with the Bat1K project which aims to catalog the genetic diversity of all living bat species. She…
In this PacBio User Group Meeting lightning talk, Shawn Polson of the University of Delaware speaks about viral metagenomes, which are more challenging to distinguish than their bacterial counterparts because…
Tina Graves-Lindsay from the McDonnell Genome Institute reports at AGBT 2020 on how her team is using PacBio sequencing to produce reference-grade human genome assemblies. With highly accurate HiFi reads,…
In a push to develop insect-based food sources for people, Brenda Oppert from the USDA has been sequencing bug genomes with PacBio technology. Long reads are essential because of the…
Domestication of clonally propagated crops such as pineapple from South America was hypothesized to be a ‘one-step operation’. We sequenced the genome of Ananas comosus var. bracteatus CB5 and assembled 513?Mb into 25 chromosomes with 29,412 genes. Comparison of the genomes of CB5, F153 and MD2 elucidated the genomic basis of fiber production, color formation, sugar accumulation and fruit maturation. We also resequenced 89 Ananas genomes. Cultivars ‘Smooth Cayenne’ and ‘Queen’ exhibited ancient and recent admixture, while ‘Singapore Spanish’ supported a one-step operation of domestication. We identified 25 selective sweeps, including a strong sweep containing a pair of tandemly duplicated bromelain inhibitors. Four candidate genes for self-incompatibility were linked in F153, but were not functional in self-compatible CB5. Our findings support the coexistence of sexual recombination and a one-step operation in the domestication of clonally propagated crops. This work guides the exploration of sexual and asexual domestication trajectories in other clonally propagated crops.
To track stepwise changes in genetic diversity and antimicrobial resistance in rapidly evolving OXA-232-producing Klebsiella pneumoniae ST14, an emerging carbapenem-resistant high-risk clone, in clinical settings.Twenty-six K. pneumoniae ST14 isolates were collected by the Korean Nationwide Surveillance of Antimicrobial Resistance system over the course of 1 year. Isolates were subjected to whole-genome sequencing and MIC determinations using 33 antibiotics from 14 classes.Single-nucleotide polymorphism (SNP) typing identified 72 unique SNP sites spanning the chromosomes of the isolates, dividing them into three clusters (I, II and III). The initial isolate possessed two plasmids with 18 antibiotic-resistance genes, including blaOXA-232, and exhibited resistance to 11 antibiotic classes. Four other plasmids containing 12 different resistance genes, including blaCTX-M-15 and strA/B, were introduced over time, providing additional resistance to aztreonam and streptomycin. Moreover, chromosomal integration of insertion sequence Ecp1-blaCTX-M-15 mediated the inactivation of mgrB responsible for colistin resistance in four isolates from cluster III. To the best of our knowledge, this is the first description of K. pneumoniae ST14 resistant to both carbapenem and colistin in South Korea. Furthermore, although some acquired genes were lost over time, the retention of 12 resistance genes and inactivation of mgrB provided resistance to 13 classes of antibiotics.We describe stepwise changes in OXA-232-producing K. pneumoniae ST14 in vivo over time in terms of antimicrobial resistance. Our findings contribute to our understanding of the evolution of emerging high-risk K. pneumoniae clones and provide reference data for future outbreaks.Copyright © 2019 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
The genomes of classical inbred mouse strains include genes derived from all three major subspecies of the house mouse, Mus musculus. We recently posited that genetic diversity in the immunoglobulin heavy chain (IGH) gene loci of C57BL/6 and BALB/c mice reflect differences in subspecies origin. To investigate this hypothesis, we conducted high-throughput sequencing of IGH gene rearrangements to document IGH variable (IGHV), joining (IGHJ), and diversity (IGHD) genes in four inbred wild-derived mouse strains (CAST/EiJ, LEWES/EiJ, MSM/MsJ, and PWD/PhJ), and a single disease model strain (NOD/ShiLtJ), collectively representing genetic backgrounds of several major mouse subspecies. A total of 341 germline IGHV sequences were inferred in the wild-derived strains, including 247 not curated in the International Immunogenetics Information System. In contrast, 83/84 inferred NOD IGHV genes had previously been observed in C57BL/6 mice. Variability among the strains examined was observed for only a single IGHJ gene, involving a description of a novel allele. In contrast, unexpected variation was found in the IGHD gene loci, with four previously unreported IGHD gene sequences being documented. Very few IGHV sequences of C57BL/6 and BALB/c mice were shared with strains representing major subspecies, suggesting that their IGH loci may be complex mosaics of genes of disparate origins. This suggests a similar level of diversity is likely present in the IGH loci of other classical inbred strains. This must now be documented if we are to properly understand inter-strain variation in models of antibody-mediated disease. This article is protected by copyright. All rights reserved.This article is protected by copyright. All rights reserved.
Large yellow croaker (Larimichthys crocea) is an economically important marine fish species of China. Due to overfishing and marine pollution, the wild stocks of this croaker have collapsed in the past decades. Meanwhile, the cultured croaker is facing the difficulties of reduced genetic diversity and low growth rate. To explore the molecular markers related to the growth traits of croaker and providing the related SNPs for the marker-assisted selection, we used double-digest restriction-site associated DNA (ddRAD) sequencing to dissect the genetic bases of growth traits in a cultured population and identify the SNPs that associated with important growth traits by GWAS. A total of 220 individuals were genotyped by ddRAD sequencing. After quality control, 27,227 SNPs were identified in 220 samples and used for GWAS analysis. We identified 13 genome-wide significant associated SNPs of growth traits on 8 chromosomes, and the beta P of these SNPs ranged from 0.01 to 0.86. Through the definition of candidate regions and gene annotation, candidate genes related to growth were identified, including important regulators such as fgf18, fgf1, nr3c1, cyp8b1, fabp2, cyp2r1, ppara, and ccm2l. We also identified SNPs and candidate genes that significantly associated with body shape, including bmp7, col1a1, col11a2, and col18a1, which are also economically important traits for large yellow croaker aquaculture. The results provided insights into the genetic basis of growth and body shape in large yellow croaker population and would provide reliable genetic markers for molecular marker-assisted selection in the future. Meanwhile, the result established a basis for our subsequent fine mapping and related gene study.
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 a reference genome with chromosome-scale sequences for Chinese chestnut (C. mollissima), the disease-resistance donor for American chestnut restoration. We also demonstrate the value of the genome as a platform for research and species restoration, including new insights into the evolution of blight resistance in Asian chestnut species, the locations in the genome of ecologically important signatures of selection differentiating American chestnut from Chinese chestnut, the identification of candidate genes for disease resistance, and preliminary comparisons of genome organization with related species.
Haplotype phasing of genetic variants is important for interpretation of the maize genome, population genetic analysis, and functional genomic analysis of allelic activity. Accordingly, accurate methods for phasing full-length isoforms are essential for functional genomics study. In this study, we performed an isoform-level phasing study in maize, using two inbred lines and their reciprocal crosses, based on single-molecule full-length cDNA sequencing. To phase and analyze full-length transcripts between hybrids and parents, we developed a tool called IsoPhase. Using this tool, we validated the majority of SNPs called against matching short read data and identified cases of allele-specific, gene-level, and isoform-level expression. Our results revealed that maize parental and hybrid lines exhibit different splicing activities. After phasing 6,847 genes in two reciprocal hybrids using embryo, endosperm and root tissues, we annotated the SNPs and identified large-effect genes. In addition, based on single-molecule sequencing, we identified parent-of-origin isoforms in maize hybrids, different novel isoforms between maize parent and hybrid lines, and imprinted genes from different tissues. Finally, we characterized variation in cis- and trans-regulatory effects. Our study provides measures of haplotypic expression that could increase power and accuracy in studies of allelic expression.
Ilyonectria mors-panacis is a serious disease hampering the production of Panax notoginseng, an important Chinese medicinal herb, widely used for its anti-inflammatory, anti-fatigue, hepato-protective, and coronary heart disease prevention effects. Here, we report the first Illumina-Pacbio hybrid sequenced draft genome assembly of I. mors-panacis strain G3B and its annotation. The availability of this genome sequence not only represents an important tool toward understanding the genetics behind the infection mechanism of I. mors-panacis strain G3B but also will help illuminate the complexities of the taxonomy of this species.
The aim of this study was to detect the transferable oxazolidinone resistance determinants (cfr, optrA and poxtA) in E. faecalis and E. faecium of swine origin in Sichuan Province, China.A total of 158 enterococci strains (93 E. faecalis and 65 E. faecium) isolated from 25 large-scale swine farms were screened for the presence of cfr, optrA and poxtA by PCR. The genetic environments of cfr, optrA and poxtA were characterized by whole genome sequencing. Transfer of oxazolidinone resistance determinants was determined by conjugation or electrotransformation experiments.The transferable oxazolidinone resistance determinants, cfr, optrA and poxtA, were detected in zero, six, and one enterococci strains, respectively. The poxtA in one E. faecalis strain was located on a 37,990 bp plasmid, which co-harbored fexB, cat, tet(L) and tet(M), and could be conjugated to E. faecalis JH2-2. One E. faecalis strain harbored two different OptrA variants, including one variant with a single substitution, Q219H, which has not been reported previously. Two optrA-carrying plasmids, pC25-1, with a size of 45,581 bp, and pC54, with a size of 64,500 bp, shared a 40,494 bp identical region that contained genetic context IS1216E-fexA-optrA-erm(A)-IS1216E, which could be electrotransformed into Staphylococcus aureus. Four different chromosomal optrA gene clusters were found in five strains, in which optrA was associated with Tn554 or Tn558 that were inserted into the radC gene.Our study highlights the fact that mobile genetic elements, such as plasmids, IS1216E, Tn554 and Tn558, may facilitate the horizontal transmission of optrA or poxtA.Copyright © 2019. Published by Elsevier Ltd.
In the wake of constant improvements in sequencing technologies, numerous insect genomes have been sequenced. Currently, 1219 insect genome-sequencing projects have been registered with the National Center for Biotechnology Information, including 401 that have genome assemblies and 155 with an official gene set of annotated protein-coding genes. Comparative genomics analysis showed that the expansion or contraction of gene families was associated with well-studied physiological traits such as immune system, metabolic detoxification, parasitism and polyphagy in insects. Here, we summarize the progress of insect genome sequencing, with an emphasis on how this impacts research on pest control. We begin with a brief introduction to the basic concepts of genome assembly, annotation and metrics for evaluating the quality of draft assemblies. We then provide an overview of genome information for numerous insect species, highlighting examples from prominent model organisms, agricultural pests and disease vectors. We also introduce the major insect genome databases. The increasing availability of insect genomic resources is beneficial for developing alternative pest control methods. However, many opportunities remain for developing data-mining tools that make maximal use of the available insect genome resources. Although rapid progress has been achieved, many challenges remain in the field of insect genomics. © 2019 The Royal Entomological Society.
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 was affected by heterozygosity of the individual sequenced, with higher accuracy for cattle and zebra finch (>97%) compared to human (82%). In addition, scaffolding with the same Hi-C chromatin contact data resulted in phased chromosome-scale scaffolds.
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