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July 7, 2019

Whole genome sequence of Pantoea ananatis R100, an antagonistic bacterium isolated from rice seed.

Pantoea ananatis is a group of bacteria, which was first reported as plant pathogen. Recently, several papers also described its biocontrol ability. In 2003, P. ananatis R100, which showed strong antagonism against several plant pathogens, was isolated from rice seeds. In this study, whole genome sequence of this strain was determined by SMRT Cell technology. The total genome size of R100 is 4,857,861bp with 4659 coding genes (CDS), 82 tRNAs and 22 rRNAs. The genome sequence of R100 may shed a light on the research of antagonism P. ananatis. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.


July 7, 2019

Complete genome sequence of Lactobacillus helveticus CAUH18, a potential probiotic strain originated from koumiss.

Here we report the complete genome sequence of Lactobacillus helveticus CAUH18, a new strain isolated from traditional fermented dairy product koumiss. Its genome has a circular 2.16Mb chromosome with no plasmid. The genome sequence indicated that this strain harbors a gene cluster involved in a novel exopolysaccharides (EPS) biosynthesis and a gene encoding cell-surface aggregation-promoting factors (APFs) to facilitate its colonization in gastrointestinal tract (GIT). This genome sequence provides a basis for further studies about its molecular genetics and probiotic functions. Copyright © 2016. Published by Elsevier B.V.


July 7, 2019

Filling in the gap of human chromosome 4: Single Molecule Real Time sequencing of macrosatellite repeats in the facioscapulohumeral muscular dystrophy locus.

A majority of facioscapulohumeral muscular dystrophy (FSHD) is caused by contraction of macrosatellite repeats called D4Z4 that are located in the subtelomeric region of human chromosome 4q35. Sequencing the FSHD locus has been technically challenging due to its long size and nearly identical nature of repeat elements. Here we report sequencing and partial assembly of a BAC clone carrying an entire FSHD locus by a single molecule real time (SMRT) sequencing technology which could produce long reads up to about 18 kb containing D4Z4 repeats. De novo assembly by Hierarchical Genome Assembly Process 1 (HGAP.1) yielded a contig of 41 kb containing all but a part of the most distal D4Z4 element. The validity of the sequence model was confirmed by an independent approach employing anchored multiple sequence alignment by Kalign using reads containing unique flanking sequences. Our data will provide a basis for further optimization of sequencing and assembly conditions of D4Z4.


July 7, 2019

High quality maize centromere 10 sequence reveals evidence of frequent recombination events.

The ancestral centromeres of maize contain long stretches of the tandemly arranged CentC repeat. The abundance of tandem DNA repeats and centromeric retrotransposons (CR) has presented a significant challenge to completely assembling centromeres using traditional sequencing methods. Here, we report a nearly complete assembly of the 1.85 Mb maize centromere 10 from inbred B73 using PacBio technology and BACs from the reference genome project. The error rates estimated from overlapping BAC sequences are 7 × 10(-6) and 5 × 10(-5) for mismatches and indels, respectively. The number of gaps in the region covered by the reassembly was reduced from 140 in the reference genome to three. Three expressed genes are located between 92 and 477 kb from the inferred ancestral CentC cluster, which lies within the region of highest centromeric repeat density. The improved assembly increased the count of full-length CR from 5 to 55 and revealed a 22.7 kb segmental duplication that occurred approximately 121,000 years ago. Our analysis provides evidence of frequent recombination events in the form of partial retrotransposons, deletions within retrotransposons, chimeric retrotransposons, segmental duplications including higher order CentC repeats, a deleted CentC monomer, centromere-proximal inversions, and insertion of mitochondrial sequences. Double-strand DNA break (DSB) repair is the most plausible mechanism for these events and may be the major driver of centromere repeat evolution and diversity. In many cases examined here, DSB repair appears to be mediated by microhomology, suggesting that tandem repeats may have evolved to efficiently repair frequent DSBs in centromeres.


July 7, 2019

BAC-pool sequencing and assembly of 19 Mb of the complex sugarcane genome.

Sequencing plant genomes are often challenging because of their complex architecture and high content of repetitive sequences. Sugarcane has one of the most complex genomes. It is highly polyploid, preserves intact homeologous chromosomes from its parental species and contains >55% repetitive sequences. Although bacterial artificial chromosome (BAC) libraries have emerged as an alternative for accessing the sugarcane genome, sequencing individual clones is laborious and expensive. Here, we present a strategy for sequencing and assembly reads produced from the DNA of pooled BAC clones. A set of 178 BAC clones, randomly sampled from the SP80-3280 sugarcane BAC library, was pooled and sequenced using the Illumina HiSeq2000 and PacBio platforms. A hybrid assembly strategy was used to generate 2,451 scaffolds comprising 19.2 MB of assembled genome sequence. Scaffolds of =20 Kb corresponded to 80% of the assembled sequences, and the full sequences of forty BACs were recovered in one or two contigs. Alignment of the BAC scaffolds with the chromosome sequences of sorghum showed a high degree of collinearity and gene order. The alignment of the BAC scaffolds to the 10 sorghum chromosomes suggests that the genome of the SP80-3280 sugarcane variety is ~19% contracted in relation to the sorghum genome. In conclusion, our data show that sequencing pools composed of high numbers of BAC clones may help to construct a reference scaffold map of the sugarcane genome.


July 7, 2019

A carbapenem-resistant Pseudomonas aeruginosa isolate harboring two copies of blaIMP-34 encoding a metallo-ß-lactamase.

A carbapenem-resistant strain of Pseudomonas aeruginosa, NCGM1984, was isolated in 2012 from a hospitalized patient in Japan. Immunochromatographic assay showed that the isolate was positive for IMP-type metallo-ß-lactamase. Complete genome sequencing revealed that NCGM1984 harbored two copies of blaIMP-34, located at different sites on the chromosome. Each blaIMP-34 was present in the same structures of the class 1 integrons, tnpA(ISPa7)-intI1-qacG-blaIMP-34-aac(6′)-Ib-qacEdelta1-sul1-orf5-tniBdelta-tniA. The isolate belonged to multilocus sequence typing ST235, one of the international high-risk clones. IMP-34, with an amino acid substitution (Glu126Gly) compared with IMP-1, hydrolyzed all ß-lactamases tested except aztreonam, and its catalytic activities were similar to IMP-1. This is the first report of a clinical isolate of an IMP-34-producing P. aeruginosa harboring two copies of blaIMP-34 on its chromosome.


July 7, 2019

Whole genome sequence and genome annotation of Colletotrichum acutatum, causal agent of anthracnose in pepper plants in South Korea

Abstract Colletotrichum acutatum is a destructive fungal pathogen which causes anthracnose in a wide range of crops. Here we report the whole genome sequence and annotation of C. acutatum strain KC05, isolated from an infected pepper in Kangwon, South Korea. Genomic DNA from the KC05 strain was used for the whole genome sequencing using a PacBio sequencer and the MiSeq system. The KC05 genome was determined to be 52,190,760 bp in size with a G + C content of 51.73% in 27 scaffolds and to contain 13,559 genes with an average length of 1516 bp. Gene prediction and annotation were performed by incorporating RNA-Seq data. The genome sequence of the KC05 was deposited at DDBJ/ENA/GenBank under the accession number LUXP00000000.


July 7, 2019

Characterization of VCC-1, a novel ambler class A carbapenemase from Vibrio cholerae isolated from imported retail shrimp sold in Canada.

One of the core goals of the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) is to monitor major meat commodities for antimicrobial resistance. Targeted studies with methodologies based on core surveillance protocols are used to examine other foods, e.g., seafood, for antimicrobial resistance to detect resistances of concern to public health. Here we report the discovery of a novel Ambler class A carbapenemase that was identified in a nontoxigenic strain of Vibrio cholerae (N14-02106) isolated from shrimp that was sold for human consumption in Canada. V. cholerae N14-02106 was resistant to penicillins, carbapenems, and monobactam antibiotics; however, PCR did not detect common ß-lactamases. Bioinformatic analysis of the whole-genome sequence of V. cholerae N14-02106 revealed on the large chromosome a novel carbapenemase (referred to here as VCC-1, for Vibrio cholerae carbapenemase 1) with sequence similarity to class A enzymes. Two copies of blaVCC-1 separated and flanked by ISVch9 (i.e., 3 copies of ISVch9) were found in an acquired 8.5-kb region inserted into a VrgG family protein gene. Cloned blaVCC-1 conferred a ß-lactam resistance profile similar to that in V. cholerae N14-02106 when it was transformed into a susceptible laboratory strain of Escherichia coli. Purified VCC-1 was found to hydrolyze penicillins, 1st-generation cephalosporins, aztreonam, and carbapenems, whereas 2nd- and 3rd-generation cephalosporins were poor substrates. Using nitrocefin as a reporter substrate, VCC-1 was moderately inhibited by clavulanic acid and tazobactam but not EDTA. In this report, we present the discovery of a novel class A carbapenemase from the food supply. Copyright © 2016, American Society for Microbiology. All Rights Reserved.


July 7, 2019

No evidence for extensive horizontal gene transfer in the genome of the tardigrade Hypsibius dujardini.

Tardigrades are meiofaunal ecdysozoans that are key to understanding the origins of Arthropoda. Many species of Tardigrada can survive extreme conditions through cryptobiosis. In a recent paper [Boothby TC, et al. (2015) Proc Natl Acad Sci USA 112(52):15976-15981], the authors concluded that the tardigrade Hypsibius dujardini had an unprecedented proportion (17%) of genes originating through functional horizontal gene transfer (fHGT) and speculated that fHGT was likely formative in the evolution of cryptobiosis. We independently sequenced the genome of H. dujardini As expected from whole-organism DNA sampling, our raw data contained reads from nontarget genomes. Filtering using metagenomics approaches generated a draft H. dujardini genome assembly of 135 Mb with superior assembly metrics to the previously published assembly. Additional microbial contamination likely remains. We found no support for extensive fHGT. Among 23,021 gene predictions we identified 0.2% strong candidates for fHGT from bacteria and 0.2% strong candidates for fHGT from nonmetazoan eukaryotes. Cross-comparison of assemblies showed that the overwhelming majority of HGT candidates in the Boothby et al. genome derived from contaminants. We conclude that fHGT into H. dujardini accounts for at most 1-2% of genes and that the proposal that one-sixth of tardigrade genes originate from functional HGT events is an artifact of undetected contamination.


July 7, 2019

Horizontal gene acquisitions, mobile element proliferation, and genome decay in the host-restricted plant pathogen Erwinia tracheiphila.

Modern industrial agriculture depends on high-density cultivation of genetically similar crop plants, creating favorable conditions for the emergence of novel pathogens with increased fitness in managed compared with ecologically intact settings. Here, we present the genome sequence of six strains of the cucurbit bacterial wilt pathogen Erwinia tracheiphila (Enterobacteriaceae) isolated from infected squash plants in New York, Pennsylvania, Kentucky, and Michigan. These genomes exhibit a high proportion of recent horizontal gene acquisitions, invasion and remarkable amplification of mobile genetic elements, and pseudogenization of approximately 20% of the coding sequences. These genome attributes indicate that E. tracheiphila recently emerged as a host-restricted pathogen. Furthermore, chromosomal rearrangements associated with phage and transposable element proliferation contribute to substantial differences in gene content and genetic architecture between the six E. tracheiphila strains and other Erwinia species. Together, these data lead us to hypothesize that E. tracheiphila has undergone recent evolution through both genome decay (pseudogenization) and genome expansion (horizontal gene transfer and mobile element amplification). Despite evidence of dramatic genomic changes, the six strains are genetically monomorphic, suggesting a recent population bottleneck and emergence into E. tracheiphila’s current ecological niche. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.


July 7, 2019

Campylobacter fetus subspecies contain conserved type IV secretion systems on multiple genomic islands and plasmids.

The features contributing to differences in pathogenicity of the Campylobacter fetus subspecies are unknown. Putative factors involved in pathogenesis are located in genomic islands that encode a type IV secretion system (T4SS) and fic domain (filamentation induced by cyclic AMP) proteins, which may disrupt host cell processes. In the genomes of 27 C. fetus strains, three phylogenetically-different T4SS-encoding regions (T4SSs) were identified: one was located in both the chromosome and in extra-chromosomal plasmids; one was located exclusively in the chromosome; and one exclusively in extra-chromosomal plasmids. We observed that C. fetus strains can contain multiple T4SSs and that homologous T4SSs can be present both in chromosomal genomic islands (GI) and on plasmids in the C. fetus strains. The GIs of the chromosomally located T4SS differed mainly by the presence of fic genes, insertion sequence elements and phage-related or hypothetical proteins. Comparative analysis showed that T4SS sequences, inserted in the same locations, were conserved in the studied C. fetus genomes. Using phylogenetic analysis of the T4SSs, it was shown that C. fetus may have acquired the T4SS regions from other Campylobacter species by horizontal gene transfer. The identified T4SSs and fic genes were found in Cff and Cfv strains, although the presence of T4SSs and fic genes were significantly associated with Cfv strains. The T4SSs and fic genes could not be associated with S-layer serotypes or geographical origin of the strains.


July 7, 2019

Fully closed genome sequences of five type strains of the genus Cronobacter and one Cronobacter sakazakii strain.

Cronobacteris associated with infant infections and the consumption of reconstituted infant formula. Here we sequenced and closed six genomes ofC. condimenti(T),C. muytjensii(T),C. universalis(T),C. malonaticus(T),C. dublinensis(T), andC. sakazakiithat can be used as reference genomes in single nucleotide polymorphism (SNP)-based next-generation sequencing (NGS) analysis for source tracking investigations. Copyright © 2016 Moine et al.


July 7, 2019

A strange endocytobiont revealed as largest virus.

A lot of endocytobionts (or endosymbionts) have been discovered within free-living amoebae in recent years. In this article the results of a long lasting effort to derive valuable data about an extraordinary spore-like infectious microorganism (endocytobiont, endosymbiont) within host amoebae (Acanthamoeba sp.) recently isolated from the contact lens case of a patient with keratitis, are presented. It took some time until this endocytobiont could be attributed to the genus Pandoravirus following a publication of two other pandoraviruses isolated from aquatic environments. Consequently the molecular biological investigation led to the taxonomic affiliation of the endocytobiont with the genus Pandoravirus and to the description of a new Pandoravirus species, Pandoravirus inopinatum after whole-genome sequencing in 2015. The fact that it was isolated from a contact lens container of a keratitis patient gives another dimension to these findings showing paradigmatically, how readily these ‘new’ giant viruses get to humans. Copyright © 2016 Elsevier Ltd. All rights reserved.


July 7, 2019

A time- and cost-effective strategy to sequence mammalian Y Chromosomes: an application to the de novo assembly of gorilla Y.

The mammalian Y Chromosome sequence, critical for studying male fertility and dispersal, is enriched in repeats and palindromes, and thus, is the most difficult component of the genome to assemble. Previously, expensive and labor-intensive BAC-based techniques were used to sequence the Y for a handful of mammalian species. Here, we present a much faster and more affordable strategy for sequencing and assembling mammalian Y Chromosomes of sufficient quality for most comparative genomics analyses and for conservation genetics applications. The strategy combines flow sorting, short- and long-read genome and transcriptome sequencing, and droplet digital PCR with novel and existing computational methods. It can be used to reconstruct sex chromosomes in a heterogametic sex of any species. We applied our strategy to produce a draft of the gorilla Y sequence. The resulting assembly allowed us to refine gene content, evaluate copy number of ampliconic gene families, locate species-specific palindromes, examine the repetitive element content, and produce sequence alignments with human and chimpanzee Y Chromosomes. Our results inform the evolution of the hominine (human, chimpanzee, and gorilla) Y Chromosomes. Surprisingly, we found the gorilla Y Chromosome to be similar to the human Y Chromosome, but not to the chimpanzee Y Chromosome. Moreover, we have utilized the assembled gorilla Y Chromosome sequence to design genetic markers for studying the male-specific dispersal of this endangered species. © 2016 Tomaszkiewicz et al.; Published by Cold Spring Harbor Laboratory Press.


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