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Search Results: 1 - 10 of 498501 matches for " Michael A. Quail "
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Insights into the genome sequence of a free-living Kinetoplastid: Bodo saltans (Kinetoplastida: Euglenozoa)
Andrew P Jackson, Michael A Quail, Matthew Berriman
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-594
Abstract: 0.4 Mbp of B. saltans genome was sequenced from 12 distinct regions and contained 178 coding sequences. As in trypanosomatids, introns were absent and %GC was elevated in coding regions, greatly assisting in gene finding. In the regions studied, roughly 60% of all genes had homologs in trypanosomatids, while 28% were Bodo-specific. Intergenic sequences were typically short, resulting in higher gene density than in trypanosomatids. Although synteny was typically conserved for those genes with trypanosomatid homologs, strict colinearity was rarely observed because gene order was regularly disrupted by Bodo-specific genes.The B. saltans genome contains both sequences homologous to trypanosomatids and sequences never seen before. Structural similarities suggest that its assembly should be solvable, and, although de novo assembly will be necessary, existing trypanosomatid projects will provide some guide to annotation. A complete genome sequence will provide an effective ancestral model for understanding the shared and derived features of known trypanosomatid genomes, but it will also identify those kinetoplastid genome features lost during the evolution of parasitism.The Kinetoplastida (Euglenozoa) are unicellular flagellates that include the trypanosomatid parasites, most notably Trypanosoma brucei, T. cruzi and Leishmania spp. These organisms cause substantial mortality and morbidity in humans and their livestock worldwide as the causative agents of African sleeping sickness, Chagas disease and leishmaniasis respectively. Bodo saltans is a free-living heterotroph found worldwide in freshwater and marine habitats. It possesses the diagnostic kinetoplastid features, such as flagella sited within a specialised flagellar pocket, glycolytic processes confined to a dedicated organelle (the 'glycosome'), and the characteristic concentration of mitochondrial DNA at the base of the flagellum (the 'kinetoplast') [1,2]. When comparing trypanosomatid parasites with each other, or
A tale of three next generation sequencing platforms: comparison of Ion Torrent, Pacific Biosciences and Illumina MiSeq sequencers
Quail Michael A,Smith Miriam,Coupland Paul,Otto Thomas D
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-341
Abstract: Background Next generation sequencing (NGS) technology has revolutionized genomic and genetic research. The pace of change in this area is rapid with three major new sequencing platforms having been released in 2011: Ion Torrent’s PGM, Pacific Biosciences’ RS and the Illumina MiSeq. Here we compare the results obtained with those platforms to the performance of the Illumina HiSeq, the current market leader. In order to compare these platforms, and get sufficient coverage depth to allow meaningful analysis, we have sequenced a set of 4 microbial genomes with mean GC content ranging from 19.3 to 67.7%. Together, these represent a comprehensive range of genome content. Here we report our analysis of that sequence data in terms of coverage distribution, bias, GC distribution, variant detection and accuracy. Results Sequence generated by Ion Torrent, MiSeq and Pacific Biosciences technologies displays near perfect coverage behaviour on GC-rich, neutral and moderately AT-rich genomes, but a profound bias was observed upon sequencing the extremely AT-rich genome of Plasmodium falciparum on the PGM, resulting in no coverage for approximately 30% of the genome. We analysed the ability to call variants from each platform and found that we could call slightly more variants from Ion Torrent data compared to MiSeq data, but at the expense of a higher false positive rate. Variant calling from Pacific Biosciences data was possible but higher coverage depth was required. Context specific errors were observed in both PGM and MiSeq data, but not in that from the Pacific Biosciences platform. Conclusions All three fast turnaround sequencers evaluated here were able to generate usable sequence. However there are key differences between the quality of that data and the applications it will support.
A Novel Linear Plasmid Mediates Flagellar Variation in Salmonella Typhi
Stephen Baker ,Jonathan Hardy,Kenneth E Sanderson,Michael Quail,Ian Goodhead,Robert A Kingsley,Julian Parkhill,Bruce Stocker ?,Gordon Dougan
PLOS Pathogens , 2007, DOI: 10.1371/journal.ppat.0030059
Abstract: Unlike the majority of Salmonella enterica serovars, Salmonella Typhi (S. Typhi), the etiological agent of human typhoid, is monophasic. S. Typhi normally harbours only the phase 1 flagellin gene (fliC), which encodes the H:d antigen. However, some S. Typhi strains found in Indonesia express an additional flagellin antigen termed H:z66. Molecular analysis of H:z66+ S. Typhi revealed that the H:z66 flagellin structural gene (fljBz66) is encoded on a linear plasmid that we have named pBSSB1. The DNA sequence of pBSSB1 was determined to be just over 27 kbp, and was predicted to encode 33 coding sequences. To our knowledge, pBSSB1 is the first non-bacteriophage–related linear plasmid to be described in the Enterobacteriaceae.
Phylogenetic Relationships of the Wolbachia of Nematodes and Arthropods
Katelyn Fenn equal contributor,Claire Conlon equal contributor,Martin Jones,Michael A Quail,Nancy E Holroyd,Julian Parkhill,Mark Blaxter
PLOS Pathogens , 2006, DOI: 10.1371/journal.ppat.0020094
Abstract: Wolbachia are well known as bacterial symbionts of arthropods, where they are reproductive parasites, but have also been described from nematode hosts, where the symbiotic interaction has features of mutualism. The majority of arthropod Wolbachia belong to clades A and B, while nematode Wolbachia mostly belong to clades C and D, but these relationships have been based on analysis of a small number of genes. To investigate the evolution and relationships of Wolbachia symbionts we have sequenced over 70 kb of the genome of wOvo, a Wolbachia from the human-parasitic nematode Onchocerca volvulus, and compared the genes identified to orthologues in other sequenced Wolbachia genomes. In comparisons of conserved local synteny, we find that wBm, from the nematode Brugia malayi, and wMel, from Drosophila melanogaster, are more similar to each other than either is to wOvo. Phylogenetic analysis of the protein-coding and ribosomal RNA genes on the sequenced fragments supports reciprocal monophyly of nematode and arthropod Wolbachia. The nematode Wolbachia did not arise from within the A clade of arthropod Wolbachia, and the root of the Wolbachia clade lies between the nematode and arthropod symbionts. Using the wOvo sequence, we identified a lateral transfer event whereby segments of the Wolbachia genome were inserted into the Onchocerca nuclear genome. This event predated the separation of the human parasite O. volvulus from its cattle-parasitic sister species, O. ochengi. The long association between filarial nematodes and Wolbachia symbionts may permit more frequent genetic exchange between their genomes.
Genetic Mapping Identifies Novel Highly Protective Antigens for an Apicomplexan Parasite
Damer P. Blake ,Karen J. Billington,Susan L. Copestake,Richard D. Oakes,Michael A. Quail,Kiew-Lian Wan,Martin W. Shirley,Adrian L. Smith
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1001279
Abstract: Apicomplexan parasites are responsible for a myriad of diseases in humans and livestock; yet despite intensive effort, development of effective sub-unit vaccines remains a long-term goal. Antigenic complexity and our inability to identify protective antigens from the pool that induce response are serious challenges in the development of new vaccines. Using a combination of parasite genetics and selective barriers with population-based genetic fingerprinting, we have identified that immunity against the most important apicomplexan parasite of livestock (Eimeria spp.) was targeted against a few discrete regions of the genome. Herein we report the identification of six genomic regions and, within two of those loci, the identification of true protective antigens that confer immunity as sub-unit vaccines. The first of these is an Eimeria maxima homologue of apical membrane antigen-1 (AMA-1) and the second is a previously uncharacterised gene that we have termed ‘immune mapped protein-1’ (IMP-1). Significantly, homologues of the AMA-1 antigen are protective with a range of apicomplexan parasites including Plasmodium spp., which suggest that there may be some characteristic(s) of protective antigens shared across this diverse group of parasites. Interestingly, homologues of the IMP-1 antigen, which is protective against E. maxima infection, can be identified in Toxoplasma gondii and Neospora caninum. Overall, this study documents the discovery of novel protective antigens using a population-based genetic mapping approach allied with a protection-based screen of candidate genes. The identification of AMA-1 and IMP-1 represents a substantial step towards development of an effective anti-eimerian sub-unit vaccine and raises the possibility of identification of novel antigens for other apicomplexan parasites. Moreover, validation of the parasite genetics approach to identify effective antigens supports its adoption in other parasite systems where legitimate protective antigen identification is difficult.
Plasmodium falciparum Variant Surface Antigen Expression Patterns during Malaria
Peter C Bull ,Matthew Berriman equal contributor,Sue Kyes equal contributor,Michael A Quail,Neil Hall,Moses M Kortok,Kevin Marsh,Chris I Newbold
PLOS Pathogens , 2005, DOI: 10.1371/journal.ppat.0010026
Abstract: The variant surface antigens expressed on Plasmodium falciparum–infected erythrocytes are potentially important targets of immunity to malaria and are encoded, at least in part, by a family of var genes, about 60 of which are present within every parasite genome. Here we use semi-conserved regions within short var gene sequence “tags” to make direct comparisons of var gene expression in 12 clinical parasite isolates from Kenyan children. A total of 1,746 var clones were sequenced from genomic and cDNA and assigned to one of six sequence groups using specific sequence features. The results show the following. (1) The relative numbers of genomic clones falling in each of the sequence groups was similar between parasite isolates and corresponded well with the numbers of genes found in the genome of a single, fully sequenced parasite isolate. In contrast, the relative numbers of cDNA clones falling in each group varied considerably between isolates. (2) Expression of sequences belonging to a relatively conserved group was negatively associated with the repertoire of variant surface antigen antibodies carried by the infected child at the time of disease, whereas expression of sequences belonging to another group was associated with the parasite “rosetting” phenotype, a well established virulence determinant. Our results suggest that information on the state of the host–parasite relationship in vivo can be provided by measurements of the differential expression of different var groups, and need only be defined by short stretches of sequence data.
Independent evolution of the core and accessory gene sets in the genus Neisseria: insights gained from the genome of Neisseria lactamica isolate 020-06
Julia S Bennett, Stephen D Bentley, Georgios S Vernikos, Michael A Quail, Inna Cherevach, Brian White, Julian Parkhill, Martin CJ Maiden
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-652
Abstract: Non-pathogenic N. lactamica exhibits very similar population structure and levels of diversity to the meningococcus, whilst gonococci are essentially recent descendents of a single clone. All three species share a common core gene set estimated to comprise around 1190 CDSs, corresponding to about 60% of the genome. However, some of the nucleotide sequence diversity within this core genome is particular to each group, indicating that cross-species recombination is rare in this shared core gene set. Other than the meningococcal cps region, which encodes the polysaccharide capsule, relatively few members of the large accessory gene pool are exclusive to one species group, and cross-species recombination within this accessory genome is frequent.The three Neisseria species groups represent coherent biological and genetic groupings which appear to be maintained by low rates of inter-species horizontal genetic exchange within the core genome. There is extensive evidence for exchange among positively selected genes and the accessory genome and some evidence of hitch-hiking of housekeeping genes with other loci. It is not possible to define a 'pathogenome' for this group of organisms and the disease causing phenotypes are therefore likely to be complex, polygenic, and different among the various disease-associated phenotypes observed.Comparison of the genomes of related bacteria that exhibit distinct pathogenic phenotypes can identify the genetic traits required for invasion and elucidate key steps in the evolution of virulence. The genus Neisseria, which comprises Gram negative oxidase positive diplococci that colonise the mucosa of humans and animals, provides an excellent model for this type of study as it includes species that are never or rarely pathogenic and two human pathogens of global significance, Neisseria meningitidis (the meningococcus) and Neisseria gonorrhoeae (the gonococcus) [1]. Neisseria lactamica is closely related to the pathogenic Neisseria [2,3] and,
Optimizing illumina next-generation sequencing library preparation for extremely at-biased genomes
Samuel O Oyola, Thomas D Otto, Yong Gu, Gareth Maslen, Magnus Manske, Susana Campino, Daniel J Turner, Bronwyn MacInnis, Dominic P Kwiatkowski, Harold P Swerdlow, Michael A Quail
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-1
Abstract: We have used our optimized conditions in parallel with standard methods to prepare Illumina sequencing libraries from a non-clinical and a clinical isolate (containing ~53% host contamination). By analyzing and comparing the quality of sequence data generated, we show that our optimized conditions that involve a PCR additive (TMAC), produces amplified libraries with improved coverage of extremely AT-rich regions and reduced bias toward GC neutral templates.We have developed a robust and optimized Next-Generation Sequencing library amplification method suitable for extremely AT-rich genomes. The new amplification conditions significantly reduce bias and retain the complexity of either extremes of base composition. This development will greatly benefit sequencing clinical samples that often require amplification due to low mass of DNA starting material.Among the eukaryotic pathogens whose genomes have so far been sequenced, the malaria parasite, Plasmodium falciparum (P. falciparum), posed the most technical challenges both in sequencing and assembly of the draft genome [1]. The biggest hurdle was the complexity of the genome, which is extremely base biased. The P. falciparum genome is very AT-rich; coding regions have a mean AT content of more than 75%, with up to 100% in intergenic and non-coding regions [2]. Although biased base composition has been a challenge to the Sanger sequencing methods, it has continued to be a major problem for the current high-throughput Next-Generation Sequencing (NGS) technologies [3]. Much work has focused on solving amplification and sequencing problems associated with high GC content but nothing has been done to improve on those caused by AT-rich parts of the genome [4,5]. Since completion of the malaria genome sequencing and the subsequent development of massively parallel sequencing technology, there has been increased effort in using genetic information obtained through re-sequencing initiatives to control and ultimately eliminate
Drug-Resistant Genotypes and Multi-Clonality in Plasmodium falciparum Analysed by Direct Genome Sequencing from Peripheral Blood of Malaria Patients
Timothy Robinson, Susana G. Campino, Sarah Auburn, Samuel A. Assefa, Spencer D. Polley, Magnus Manske, Bronwyn MacInnis, Kirk A. Rockett, Gareth L. Maslen, Mandy Sanders, Michael A. Quail, Peter L. Chiodini, Dominic P. Kwiatkowski, Taane G. Clark, Colin J. Sutherland
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023204
Abstract: Naturally acquired blood-stage infections of the malaria parasite Plasmodium falciparum typically harbour multiple haploid clones. The apparent number of clones observed in any single infection depends on the diversity of the polymorphic markers used for the analysis, and the relative abundance of rare clones, which frequently fail to be detected among PCR products derived from numerically dominant clones. However, minority clones are of clinical interest as they may harbour genes conferring drug resistance, leading to enhanced survival after treatment and the possibility of subsequent therapeutic failure. We deployed new generation sequencing to derive genome data for five non-propagated parasite isolates taken directly from 4 different patients treated for clinical malaria in a UK hospital. Analysis of depth of coverage and length of sequence intervals between paired reads identified both previously described and novel gene deletions and amplifications. Full-length sequence data was extracted for 6 loci considered to be under selection by antimalarial drugs, and both known and previously unknown amino acid substitutions were identified. Full mitochondrial genomes were extracted from the sequencing data for each isolate, and these are compared against a panel of polymorphic sites derived from published or unpublished but publicly available data. Finally, genome-wide analysis of clone multiplicity was performed, and the number of infecting parasite clones estimated for each isolate. Each patient harboured at least 3 clones of P. falciparum by this analysis, consistent with results obtained with conventional PCR analysis of polymorphic merozoite antigen loci. We conclude that genome sequencing of peripheral blood P. falciparum taken directly from malaria patients provides high quality data useful for drug resistance studies, genomic structural analyses and population genetics, and also robustly represents clonal multiplicity.
The Genome of Mycobacterium Africanum West African 2 Reveals a Lineage-Specific Locus and Genome Erosion Common to the M. tuberculosis Complex
Stephen D. Bentley,I?aki Comas,Josephine M. Bryant,Danielle Walker,Noel H. Smith,Simon R. Harris,Scott Thurston,Sebastien Gagneux,Jonathan Wood,Martin Antonio,Michael A. Quail,Florian Gehre,Richard A. Adegbola,Julian Parkhill,Bouke C. de Jong
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001552
Abstract: Background M. africanum West African 2 constitutes an ancient lineage of the M. tuberculosis complex that commonly causes human tuberculosis in West Africa and has an attenuated phenotype relative to M. tuberculosis. Methodology/Principal Findings In search of candidate genes underlying these differences, the genome of M. africanum West African 2 was sequenced using classical capillary sequencing techniques. Our findings reveal a unique sequence, RD900, that was independently lost during the evolution of two important lineages within the complex: the “modern” M. tuberculosis group and the lineage leading to M. bovis. Closely related to M. bovis and other animal strains within the M. tuberculosis complex, M. africanum West African 2 shares an abundance of pseudogenes with M. bovis but also with M. africanum West African clade 1. Comparison with other strains of the M. tuberculosis complex revealed pseudogenes events in all the known lineages pointing toward ongoing genome erosion likely due to increased genetic drift and relaxed selection linked to serial transmission-bottlenecks and an intracellular lifestyle. Conclusions/Significance The genomic differences identified between M. africanum West African 2 and the other strains of the Mycobacterium tuberculosis complex may explain its attenuated phenotype, and pave the way for targeted experiments to elucidate the phenotypic characteristic of M. africanum. Moreover, availability of the whole genome data allows for verification of conservation of targets used for the next generation of diagnostics and vaccines, in order to ensure similar efficacy in West Africa.
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