July 7, 2019
Advancing benchmarks for genome sequencing
Several recent benchmarking efforts provide reference datasets and samples to improve genome sequencing and calling of germline and somatic mutations.
Auto Tag: De novo assembly
July 7, 2019
Complete genome of the marine bacterium Wenzhouxiangella marina KCTC 42284(T).
Wenzhouxiangella marina is an obligatory aerobic, Gram-negative, non-motile, rod-shaped bacterium that was isolated from the culture broth of marine microalgae, Picochlorum sp. 122. Here we report the 3.67 MB complete genome (65.26 G+C%) of W. marina KCTC 42284(T) encoding 3,016 protein-coding genes, 43 tRNAs and one rRNA operon. The genomic information supports multiple horizontal gene transfer (HGT) events in the history of W. marina, possibly with other marine bacteria co-existing in marine habitats. Evaluation of genomic signatures revealed 19 such HGT-derived genomic islands. Of these, eight were also supported by “genomic context” that refers to the existence of integrases, transposases and tmRNA genes either inside or in near vicinity to the island. The addition of W. marina genome expands the repertoire of marine bacterial genomic diversity, especially because the strain represents the sole genomic resource of a novel taxonomic family in the bacterial order Chromatiales. Copyright © 2015 Elsevier B.V. All rights reserved.
July 7, 2019
Genome sequence of a urease-positive Campylobacter lari strain.
Campylobacter lari is frequently isolated from shore birds and can cause illness in humans. Here, we report the draft whole-genome sequence of a urease-positive strain of C. lari that was isolated in estuarial water on the coast of Delaware, USA. Copyright © 2015 Meinersmann et al.
July 7, 2019
Complete genome sequence of a cyanotroph, Pseudomonas fluorescens NCIMB 11764, employing Single-Molecule Real-Time Technology.
We report here the application of single-molecule real-time sequencing for determining the entire genome structure of the cyanotroph Pseudomonas fluorescens NCIMB 11764. Copyright © 2015 Jones and Kunz.
July 7, 2019
Jitterbug: somatic and germline transposon insertion detection at single-nucleotide resolution.
Transposable elements are major players in genome evolution. Transposon insertion polymorphisms can translate into phenotypic differences in plants and animals and are linked to different diseases including human cancer, making their characterization highly relevant to the study of genome evolution and genetic diseases. Here we present Jitterbug, a novel tool that identifies transposable element insertion sites at single-nucleotide resolution based on the pairedend mapping and clipped-read signatures produced by NGS alignments. Jitterbug can be easily integrated into existing NGS analysis pipelines, using the standard BAM format produced by frequently applied alignment tools (e.g. bwa, bowtie2), with no need to realign reads to a set of consensus transposon sequences. Jitterbug is highly sensitive and able to recall transposon insertions with a very high specificity, as demonstrated by benchmarks in the human and Arabidopsis genomes, and validation using long PacBio reads. In addition, Jitterbug estimates the zygosity of transposon insertions with high accuracy and can also identify somatic insertions. We demonstrate that Jitterbug can identify mosaic somatic transposon movement using sequenced tumor-normal sample pairs and allows for estimating the cancer cell fraction of clones containing a somatic TE insertion. We suggest that the independent methods we use to evaluate performance are a step towards creating a gold standard dataset for benchmarking structural variant prediction tools.
July 7, 2019
Complete genome sequence of Mycobacterium bovis clinical strain 1595, isolated from the laryngopharyngeal lymph node of South Korean cattle.
Mycobacterium bovis strain 1595 was isolated from the lymph node of South Korean native cattle. The complete genome sequence of strain 1595 was determined in 2 contigs and was found to be 4,351,712 bp in size, with a 65.64% G+C content and 4,358 predicted protein-coding genes. Copyright © 2015 Kim et al.
July 7, 2019
Comparison of whole-genome sequences from two colony morphovars of Burkholderia pseudomallei.
The entire genomes of two isogenic morphovars (vgh16W and vgh16R) of Burkholderia pseudomallei were sequenced. A comparison of the sequences from both strains indicates that they show 99.99% identity, are composed of 22 tandem repeated sequences with <100 bp of indels, and have 199 single-base variants. Copyright © 2015 Hsueh et al.
July 7, 2019
Complete genome sequence of the Clostridium difficile type strain DSM 1296T.
In this study, we sequenced the complete genome of the Clostridium difficile type strain DSM 1296(T). A combination of single-molecule real-time (SMRT) and Illumina sequencing technology revealed the presence of one chromosome and two extrachromosomal elements, the bacteriophage phiCDIF1296T and a putative plasmid-like structure harboring genes of another bacteriophage. Copyright © 2015 Riedel et al.
July 7, 2019
Population genomics reveals additive and replacing horizontal gene transfers in the emerging pathogen Dickeya solani.
Dickeya solani is an emerging pathogen that causes soft rot and blackleg diseases in several crops including Solanum tuberosum, but little is known about its genomic diversity and evolution.We combined Illumina and PacBio technologies to complete the genome sequence of D. solani strain 3337 that was used as a reference to compare with 19 other genomes (including that of the type strain IPO2222(T)) which were generated by Illumina technology. This population genomic analysis highlighted an unexpected variability among D. solani isolates since it led to the characterization of two distinct sub-groups within the D. solani species. This approach also revealed different types of variations such as scattered SNP/InDel variations as well as replacing and additive horizontal gene transfers (HGT). Infra-species (between the two D. solani sub-groups) and inter-species (between D. solani and D. dianthicola) replacing HGTs were observed. Finally, this work pointed that genetic and functional variation in the motility trait could contribute to aggressiveness variability in D. solani.This work revealed that D. solani genomic variability may be caused by SNPs/InDels as well as replacing and additive HGT events, including plasmid acquisition; hence the D. solani genomes are more dynamic than that were previously proposed. This work alerts on precautions in molecular diagnosis of this emerging pathogen.
July 7, 2019
Completing the human genome: the progress and challenge of satellite DNA assembly.
Genomic studies rely on accurate chromosome assemblies to explore sequence-based models of cell biology, evolution and biomedical disease. However, even the extensively studied human genome has not yet reached a complete, ‘telomere-to-telomere’, chromosome assembly. The largest assembly gaps remain in centromeric regions and acrocentric short arms, sites known to contain megabase-sized arrays of tandem repeats, or satellite DNAs. This review aims to briefly address the progress and challenges of generating correct assemblies of satellite DNA arrays. Although the focus is placed on the human genome, many concepts presented here are applicable to other genomes.
July 7, 2019
The Brachypodium distachyon reference genome
Grasses provide the bulk of human calories but improvement in grass yields is hindered by the characteristically large and complex genomes of these species; the genomes of wheat, maize, and sugar cane are 17,000, 2300, and 10,000 Mb, respectively. Brachypodium distachyon has one of the smallest genomes of all grasses at 272 Mb, and a number of key traits that make it a good model grass. Brachypodium was the fourth sequenced grass genome, after rice, Sorghum, and maize, and was the first sequenced in the Pooideae subfamily, a diverse group that includes wheat, barley, oat, and rye. The Brachypodium genome was sequenced using a whole genome shotgun approach with Sanger sequencing and is nearly complete with 99.6 % of the sequences anchored to five chromosomes. Sequencing of Brachypodium enabled comparative genomic analysis of grass genomes and shed light on processes involved in chromosome fusions and maintenance of a small genome. The high-quality Brachypodium genome sequence provides a framework for gene expression atlases, resequencing, quantitative trait loci (QTL) mapping, GWAS, and ENCODE datasets. The wealth of Brachypodium genomic resources have cemented its utility as a model organism and will facilitate translational work for improving the grasses that feed the world.
July 7, 2019
Genome sequence of Geobacillus thermoglucosidasius DSM2542, a platform hosts for biotechnological applications with industrial potential.
Thermophilic Geobacillus thermoglucosidasius could ferment a wide range of substrates with low nutrient requirements for growth. Here, the first released the complete genome sequence of G. thermoglucosidasius DSM2542 may facilitate the design of rational strategies for further strain improvements and provide information for exploring industrially interesting enzymes with thermotolerant properties. Copyright © 2015 Elsevier B.V. All rights reserved.
July 7, 2019
Complete genome sequence of Bifidobacterium longum KCTC 12200BP, a probiotic strain promoting the intestinal health.
Bifidobacteria constitute a major group of beneficial intestinal bacteria, and are therefore often used to formulate probiotic products in combination with lactic acid bacteria. The availability of bifidobacterial genome sequences has broadened our knowledge on health-promoting factors as well as their safety assessments. Here, we present the complete genome sequence of Bifidobacterium longum CBT BG7 that consists of a 2.45-Mb chromosome and a plasmid. Copyright © 2015. Published by Elsevier B.V.
July 7, 2019
A full genomic characterization of the development of a stable Small Colony Variant cell-type by a clinical Staphylococcus aureus strain.
A key to persistent and recurrent Staphylococcus aureus infections is its ability to adapt to diverse and toxic conditions. This ability includes a switch into a biofilm or to the quasi-dormant Small Colony Variant (SCV). The development and molecular attributes of SCVs have been difficult to study due to their rapid reversion to their parental cell-type. We recently described the unique induction of a matrix-embedded and stable SCV cell-type in a clinical S. aureus strain (WCH-SK2) by growing the cells with limiting conditions for a prolonged timeframe. Here we further study their characteristics. They possessed an increased viability in the presence of antibiotics compared to their non-SCV form. Their stability implied that there had been genetic changes; we therefore determined both the genome sequence of WCH-SK2 and its stable SCV form at a single base resolution, employing Single Molecular Real-Time (SMRT) sequencing that enabled the methylome to also be determined. The genetic features of WCH-SK2 have been identified; the SCCmec type, the pathogenicity and genetic islands and virulence factors. The genetic changes that had occurred in the stable SCV form were identified; most notably being in MgrA, a global regulator, and RsbU, a phosphoserine phosphatase within the regulatory pathway of the sigma factor SigB. There was a shift in the methylomes of the non-SCV and stable SCV forms. We have also shown a similar induction of this cell-type in other S. aureus strains and performed a genetic comparison to these and other S. aureus genomes. We additionally map RNAseq data to the WCH-SK2 genome in a transcriptomic analysis of the parental, SCV and stable SCV cells. The results from this study represent the unique identification of a suite of epigenetic, genetic and transcriptional factors that are implicated in the switch in S. aureus to its persistent SCV form. Copyright © 2015 Elsevier B.V. All rights reserved.
July 7, 2019
The genome and methylome of a beetle with complex social behavior, Nicrophorus vespilloides (Coleoptera: Silphidae).
Testing for conserved and novel mechanisms underlying phenotypic evolution requires a diversity of genomes available for comparison spanning multiple independent lineages. For example, complex social behavior in insects has been investigated primarily with eusocial lineages, nearly all of which are Hymenoptera. If conserved genomic influences on sociality do exist, we need data from a wider range of taxa that also vary in their levels of sociality. Here, we present the assembled and annotated genome of the subsocial beetle Nicrophorus vespilloides, a species long used to investigate evolutionary questions of complex social behavior. We used this genome to address two questions. First, do aspects of life history, such as using a carcass to breed, predict overlap in gene models more strongly than phylogeny? We found that the overlap in gene models was similar between N. vespilloides and all other insect groups regardless of life history. Second, like other insects with highly developed social behavior but unlike other beetles, does N. vespilloides have DNA methylation? We found strong evidence for an active DNA methylation system. The distribution of methylation was similar to other insects with exons having the most methylated CpGs. Methylation status appears highly conserved; 85% of the methylated genes in N. vespilloides are also methylated in the hymentopteran Nasonia vitripennis. The addition of this genome adds a coleopteran resource to answer questions about the evolution and mechanistic basis of sociality and to address questions about the potential role of methylation in social behavior. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.