Publications by authors named "Jérôme Mariette"

20 Publications

  • Page 1 of 1

Conserved white-rot enzymatic mechanism for wood decay in the Basidiomycota genus Pycnoporus.

DNA Res 2020 Apr;27(2)

INRAE, UMR1163, Biodiversity and Biotechnology of Fungi, Aix Marseille University, 13009 Marseille, France.

White-rot (WR) fungi are pivotal decomposers of dead organic matter in forest ecosystems and typically use a large array of hydrolytic and oxidative enzymes to deconstruct lignocellulose. However, the extent of lignin and cellulose degradation may vary between species and wood type. Here, we combined comparative genomics, transcriptomics and secretome proteomics to identify conserved enzymatic signatures at the onset of wood-decaying activity within the Basidiomycota genus Pycnoporus. We observed a strong conservation in the genome structures and the repertoires of protein-coding genes across the four Pycnoporus species described to date, despite the species having distinct geographic distributions. We further analysed the early response of P. cinnabarinus, P. coccineus and P. sanguineus to diverse (ligno)-cellulosic substrates. We identified a conserved set of enzymes mobilized by the three species for breaking down cellulose, hemicellulose and pectin. The co-occurrence in the exo-proteomes of H2O2-producing enzymes with H2O2-consuming enzymes was a common feature of the three species, although each enzymatic partner displayed independent transcriptional regulation. Finally, cellobiose dehydrogenase-coding genes were systematically co-regulated with at least one AA9 lytic polysaccharide monooxygenase gene, indicative of enzymatic synergy in vivo. This study highlights a conserved core white-rot fungal enzymatic mechanism behind the wood-decaying process.
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http://dx.doi.org/10.1093/dnares/dsaa011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406137PMC
April 2020

Experimental quantification of pollen with DNA metabarcoding using ITS1 and trnL.

Sci Rep 2020 03 6;10(1):4202. Epub 2020 Mar 6.

Laboratoire Evolution and Diversité Biologique EDB, CNRS, UMR 5174, Université Toulouse III Paul Sabatier, F-31062, Toulouse, France.

Although the use of metabarcoding to identify taxa in DNA mixtures is widely approved, its reliability in quantifying taxon abundance is still the subject of debate. In this study we investigated the relationships between the amount of pollen grains in mock solutions and the abundance of high-throughput sequence reads and how the relationship was affected by the pollen counting methodology, the number of PCR cycles, the type of markers and plant species whose pollen grains have different characteristics. We found a significant positive relationship between the number of DNA sequences and the number of pollen grains in the mock solutions. However, better relationships were obtained with light microscopy as a pollen grain counting method compared with flow cytometry, with the chloroplastic trnL marker compared with ribosomal ITS1 and with 30 when compared with 25 or 35 PCR cycles. We provide a list of recommendations to improve pollen quantification.
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http://dx.doi.org/10.1038/s41598-020-61198-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7060345PMC
March 2020

Unsupervised multiple kernel learning for heterogeneous data integration.

Bioinformatics 2018 03;34(6):1009-1015

MIAT, Université de Toulouse, INRA, 31326 Castanet-Tolosan, France.

Motivation: Recent high-throughput sequencing advances have expanded the breadth of available omics datasets and the integrated analysis of multiple datasets obtained on the same samples has allowed to gain important insights in a wide range of applications. However, the integration of various sources of information remains a challenge for systems biology since produced datasets are often of heterogeneous types, with the need of developing generic methods to take their different specificities into account.

Results: We propose a multiple kernel framework that allows to integrate multiple datasets of various types into a single exploratory analysis. Several solutions are provided to learn either a consensus meta-kernel or a meta-kernel that preserves the original topology of the datasets. We applied our framework to analyse two public multi-omics datasets. First, the multiple metagenomic datasets, collected during the TARA Oceans expedition, was explored to demonstrate that our method is able to retrieve previous findings in a single kernel PCA as well as to provide a new image of the sample structures when a larger number of datasets are included in the analysis. To perform this analysis, a generic procedure is also proposed to improve the interpretability of the kernel PCA in regards with the original data. Second, the multi-omics breast cancer datasets, provided by The Cancer Genome Atlas, is analysed using a kernel Self-Organizing Maps with both single and multi-omics strategies. The comparison of these two approaches demonstrates the benefit of our integration method to improve the representation of the studied biological system.

Availability And Implementation: Proposed methods are available in the R package mixKernel, released on CRAN. It is fully compatible with the mixOmics package and a tutorial describing the approach can be found on mixOmics web site http://mixomics.org/mixkernel/.

Contact: jerome.mariette@inra.fr or nathalie.villa-vialaneix@inra.fr.

Supplementary Information: Supplementary data are available at Bioinformatics online.
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http://dx.doi.org/10.1093/bioinformatics/btx682DOI Listing
March 2018

Using metabarcoding to reveal and quantify plant-pollinator interactions.

Sci Rep 2016 06 3;6:27282. Epub 2016 Jun 3.

Laboratoire Evolution and Diversité Biologique EDB, Université Toulouse III Paul Sabatier, F-31062 Toulouse, France.

Given the ongoing decline of both pollinators and plants, it is crucial to implement effective methods to describe complex pollination networks across time and space in a comprehensive and high-throughput way. Here we tested if metabarcoding may circumvent the limits of conventional methodologies in detecting and quantifying plant-pollinator interactions. Metabarcoding experiments on pollen DNA mixtures described a positive relationship between the amounts of DNA from focal species and the number of trnL and ITS1 sequences yielded. The study of pollen loads of insects captured in plant communities revealed that as compared to the observation of visits, metabarcoding revealed 2.5 times more plant species involved in plant-pollinator interactions. We further observed a tight positive relationship between the pollen-carrying capacities of insect taxa and the number of trnL and ITS1 sequences. The number of visits received per plant species also positively correlated to the number of their ITS1 and trnL sequences in insect pollen loads. By revealing interactions hard to observe otherwise, metabarcoding significantly enlarges the spatiotemporal observation window of pollination interactions. By providing new qualitative and quantitative information, metabarcoding holds great promise for investigating diverse facets of interactions and will provide a new perception of pollination networks as a whole.
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http://dx.doi.org/10.1038/srep27282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4891682PMC
June 2016

Jflow: a workflow management system for web applications.

Bioinformatics 2016 Feb 10;32(3):456-8. Epub 2015 Oct 10.

Plate-forme Bio-informatique Genotoul, INRA, UR875 Mathmatiques et Informatique Appliques Toulouse, Castanet-Tolosan, France and Plate-forme SIGENAE, INRA, GenPhyse, Castanet-Tolosan Cedex, France.

Summary: Biologists produce large data sets and are in demand of rich and simple web portals in which they can upload and analyze their files. Providing such tools requires to mask the complexity induced by the needed High Performance Computing (HPC) environment. The connection between interface and computing infrastructure is usually specific to each portal. With Jflow, we introduce a Workflow Management System (WMS), composed of jQuery plug-ins which can easily be embedded in any web application and a Python library providing all requested features to setup, run and monitor workflows.

Availability And Implementation: Jflow is available under the GNU General Public License (GPL) at http://bioinfo.genotoul.fr/jflow. The package is coming with full documentation, quick start and a running test portal.

Contact: Jerome.Mariette@toulouse.inra.fr.
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http://dx.doi.org/10.1093/bioinformatics/btv589DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5859998PMC
February 2016

Contrasted effects of natural complex mixtures of PAHs and metals on oxygen cycle in a microbial mat.

Chemosphere 2015 Sep 15;135:189-201. Epub 2015 May 15.

Equipe Environnement et Microbiologie, UMR IPREM 5254, IBEAS BP 1155, Université de Pau et des Pays de l'Adour, 64013 Pau cedex, France.

The contamination of polluted environments is often due to a complex mixture of pollutants sometimes at trace levels which nevertheless may have significant effects on the diversity and functioning of organisms. The aim of this study was to assess the functional responses of a microbial mat exposed to a natural complex mixture of PAHs and metals as a function of the maturation stage of the biofilm. Microbial mats sampled in a slightly polluted environment were exposed to contaminated water of a retention basin of an oil refinery. The responses of the microbial mats differed according to season. In spring 2012, strong inhibition of both oxygen production and respiration was observed relative to the control, with rates representing less than 5% of the control after 72 h of incubation. A decrease of microbial activities was followed by a decrease of the coupling between autotrophs and heterotrophs. In contrast, in autumn 2012, no significant changes for oxygen production and respiration were observed and the coupling between autotrophs and heterotrophs was not altered. The differences observed between the spring and autumn mats might be explained by the maturity of the microbial mat with dominance of heterotrophic bacteria in spring, and diatoms and cyanobacteria in autumn, as well as by the differences in the chemical composition of the complex mixture of PAHs and metals.
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http://dx.doi.org/10.1016/j.chemosphere.2015.04.037DOI Listing
September 2015

The BioMart community portal: an innovative alternative to large, centralized data repositories.

Authors:
Damian Smedley Syed Haider Steffen Durinck Luca Pandini Paolo Provero James Allen Olivier Arnaiz Mohammad Hamza Awedh Richard Baldock Giulia Barbiera Philippe Bardou Tim Beck Andrew Blake Merideth Bonierbale Anthony J Brookes Gabriele Bucci Iwan Buetti Sarah Burge Cédric Cabau Joseph W Carlson Claude Chelala Charalambos Chrysostomou Davide Cittaro Olivier Collin Raul Cordova Rosalind J Cutts Erik Dassi Alex Di Genova Anis Djari Anthony Esposito Heather Estrella Eduardo Eyras Julio Fernandez-Banet Simon Forbes Robert C Free Takatomo Fujisawa Emanuela Gadaleta Jose M Garcia-Manteiga David Goodstein Kristian Gray José Afonso Guerra-Assunção Bernard Haggarty Dong-Jin Han Byung Woo Han Todd Harris Jayson Harshbarger Robert K Hastings Richard D Hayes Claire Hoede Shen Hu Zhi-Liang Hu Lucie Hutchins Zhengyan Kan Hideya Kawaji Aminah Keliet Arnaud Kerhornou Sunghoon Kim Rhoda Kinsella Christophe Klopp Lei Kong Daniel Lawson Dejan Lazarevic Ji-Hyun Lee Thomas Letellier Chuan-Yun Li Pietro Lio Chu-Jun Liu Jie Luo Alejandro Maass Jerome Mariette Thomas Maurel Stefania Merella Azza Mostafa Mohamed Francois Moreews Ibounyamine Nabihoudine Nelson Ndegwa Céline Noirot Cristian Perez-Llamas Michael Primig Alessandro Quattrone Hadi Quesneville Davide Rambaldi James Reecy Michela Riba Steven Rosanoff Amna Ali Saddiq Elisa Salas Olivier Sallou Rebecca Shepherd Reinhard Simon Linda Sperling William Spooner Daniel M Staines Delphine Steinbach Kevin Stone Elia Stupka Jon W Teague Abu Z Dayem Ullah Jun Wang Doreen Ware Marie Wong-Erasmus Ken Youens-Clark Amonida Zadissa Shi-Jian Zhang Arek Kasprzyk

Nucleic Acids Res 2015 Jul 20;43(W1):W589-98. Epub 2015 Apr 20.

Center for Translational Genomics and Bioinformatics San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia

The BioMart Community Portal (www.biomart.org) is a community-driven effort to provide a unified interface to biomedical databases that are distributed worldwide. The portal provides access to numerous database projects supported by 30 scientific organizations. It includes over 800 different biological datasets spanning genomics, proteomics, model organisms, cancer data, ontology information and more. All resources available through the portal are independently administered and funded by their host organizations. The BioMart data federation technology provides a unified interface to all the available data. The latest version of the portal comes with many new databases that have been created by our ever-growing community. It also comes with better support and extensibility for data analysis and visualization tools. A new addition to our toolbox, the enrichment analysis tool is now accessible through graphical and web service interface. The BioMart community portal averages over one million requests per day. Building on this level of service and the wealth of information that has become available, the BioMart Community Portal has introduced a new, more scalable and cheaper alternative to the large data stores maintained by specialized organizations.
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http://dx.doi.org/10.1093/nar/gkv350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4489294PMC
July 2015

Intra-host viral variability in children clinically infected with H1N1 (2009) pandemic influenza.

Infect Genet Evol 2015 Jul 16;33:47-54. Epub 2015 Apr 16.

Université de Toulouse, INP, ENVT, Toulouse F-31076, France; INRA, UMR 1225, IHAP, Toulouse F-31076, France.

Recent in-depth genetic analyses of influenza A virus samples have revealed patterns of intra-host viral genetic variability in a variety of relevant systems. These have included laboratory infected poultry, horses, pigs, chicken eggs and swine respiratory cells, as well as naturally infected poultry and horses. In humans, next generation sequencing techniques have enabled the study of genetic variability at specific positions of the viral genome. The present study investigated how 454 pyrosequencing could help unravel intra-host genetic diversity patterns on the full-length viral hæmagglutinin and neuraminidase genes from human H1N1 (2009) pandemic influenza clinical cases. This approach revealed unexpected patterns of co-infection in a 3-week old toddler, arising from rapid and complex reassortment phenomena on a local epidemiological scale. It also suggested the possible existence of very low frequency mutants resistant to neuraminidase inhibitors in two untreated patients. As well as revealing patterns of intra-host viral variability, this report highlights technical challenges in the appraisal of scientifically and medically relevant topics such as the natural occurrence of homologous recombination or very low frequency drug-resistant variants in influenza virus populations.
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http://dx.doi.org/10.1016/j.meegid.2015.04.009DOI Listing
July 2015

Complete Genome Sequence of a Field Strain of Peste des Petits Ruminants Virus Isolated during 2010-2014 Epidemics in Senegal.

Genome Announc 2014 Sep 18;2(5). Epub 2014 Sep 18.

Peste des petits ruminants virus (PPRV) infection is expanding and results in regular epizootic activities in Africa, the Middle East, and Asia. Here, we report the complete genome sequence of a field strain of PPRV isolated in Senegal (SnDk11I13) in 2013.
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http://dx.doi.org/10.1128/genomeA.00772-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4175193PMC
September 2014

jvenn: an interactive Venn diagram viewer.

BMC Bioinformatics 2014 Aug 29;15:293. Epub 2014 Aug 29.

Plate-forme bio-informatique Genotoul/MIA-T, INRA, Borde Rouge, 31326 Castanet-Tolosan, France.

Background: Venn diagrams are commonly used to display list comparison. In biology, they are widely used to show the differences between gene lists originating from different differential analyses, for instance. They thus allow the comparison between different experimental conditions or between different methods. However, when the number of input lists exceeds four, the diagram becomes difficult to read. Alternative layouts and dynamic display features can improve its use and its readability.

Results: jvenn is a new JavaScript library. It processes lists and produces Venn diagrams. It handles up to six input lists and presents results using classical or Edwards-Venn layouts. User interactions can be controlled and customized. Finally, jvenn can easily be embeded in a web page, allowing to have dynamic Venn diagrams.

Conclusions: jvenn is an open source component for web environments helping scientists to analyze their data. The library package, which comes with full documentation and an example, is freely available at http://bioinfo.genotoul.fr/jvenn.
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http://dx.doi.org/10.1186/1471-2105-15-293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4261873PMC
August 2014

The genome of the white-rot fungus Pycnoporus cinnabarinus: a basidiomycete model with a versatile arsenal for lignocellulosic biomass breakdown.

BMC Genomics 2014 Jun 18;15:486. Epub 2014 Jun 18.

INRA, UMR1163 Biotechnologie des Champignons Filamenteux, Aix-Marseille Université, Polytech Marseille, 163 avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France.

Background: Saprophytic filamentous fungi are ubiquitous micro-organisms that play an essential role in photosynthetic carbon recycling. The wood-decayer Pycnoporus cinnabarinus is a model fungus for the study of plant cell wall decomposition and is used for a number of applications in green and white biotechnology.

Results: The 33.6 megabase genome of P. cinnabarinus was sequenced and assembled, and the 10,442 predicted genes were functionally annotated using a phylogenomic procedure. In-depth analyses were carried out for the numerous enzyme families involved in lignocellulosic biomass breakdown, for protein secretion and glycosylation pathways, and for mating type. The P. cinnabarinus genome sequence revealed a consistent repertoire of genes shared with wood-decaying basidiomycetes. P. cinnabarinus is thus fully equipped with the classical families involved in cellulose and hemicellulose degradation, whereas its pectinolytic repertoire appears relatively limited. In addition, P. cinnabarinus possesses a complete versatile enzymatic arsenal for lignin breakdown. We identified several genes encoding members of the three ligninolytic peroxidase types, namely lignin peroxidase, manganese peroxidase and versatile peroxidase. Comparative genome analyses were performed in fungi displaying different nutritional strategies (white-rot and brown-rot modes of decay). P. cinnabarinus presents a typical distribution of all the specific families found in the white-rot life style. Growth profiling of P. cinnabarinus was performed on 35 carbon sources including simple and complex substrates to study substrate utilization and preferences. P. cinnabarinus grew faster on crude plant substrates than on pure, mono- or polysaccharide substrates. Finally, proteomic analyses were conducted from liquid and solid-state fermentation to analyze the composition of the secretomes corresponding to growth on different substrates. The distribution of lignocellulolytic enzymes in the secretomes was strongly dependent on growth conditions, especially for lytic polysaccharide mono-oxygenases.

Conclusions: With its available genome sequence, P. cinnabarinus is now an outstanding model system for the study of the enzyme machinery involved in the degradation or transformation of lignocellulosic biomass.
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http://dx.doi.org/10.1186/1471-2164-15-486DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4101180PMC
June 2014

RNAbrowse: RNA-Seq de novo assembly results browser.

PLoS One 2014 13;9(5):e96821. Epub 2014 May 13.

Plate-forme bio-informatique Genotoul/Biométrie et Intelligence Artificielle, INRA, Castanet-Tolosan, France; Plate-forme SIGENAE/Génétique Cellulaire, INRA, Castanet-Tolosan, France.

Transcriptome analysis based on a de novo assembly of next generation RNA sequences is now performed routinely in many laboratories. The generated results, including contig sequences, quantification figures, functional annotations and variation discovery outputs are usually bulky and quite diverse. This article presents a user oriented storage and visualisation environment permitting to explore the data in a top-down manner, going from general graphical views to all possible details. The software package is based on biomart, easy to install and populate with local data. The software package is available under the GNU General Public License (GPL) at http://bioinfo.genotoul.fr/RNAbrowse.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0096821PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4019526PMC
January 2015

Novel avian coronavirus and fulminating disease in guinea fowl, France.

Emerg Infect Dis 2014 Jan;20(1):105-8

For decades, French guinea fowl have been affected by fulminating enteritis of unclear origin. By using metagenomics, we identified a novel avian gammacoronavirus associated with this disease that is distantly related to turkey coronaviruses. Fatal respiratory diseases in humans have recently been caused by coronaviruses of animal origin.
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http://dx.doi.org/10.3201/eid2001.130774DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3884723PMC
January 2014

Whole-genome, deep pyrosequencing analysis of a duck influenza A virus evolution in swine cells.

Infect Genet Evol 2013 Aug 7;18:31-41. Epub 2013 May 7.

Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.

We studied the sub-population level evolution of a duck influenza A virus isolate during passage in swine tracheal cells. The complete genomes of the A/mallard/Netherlands/10-Nmkt/1999 strain and its swine cell-passaged descendent were analysed by 454 pyrosequencing with coverage depth ranging from several hundred to several thousand reads at any point. This allowed characterization of defined minority sub-populations of gene segments 2, 3, 4, 5, 7, and 8 present in the original isolate. These minority sub-populations ranged between 9.5% (for segment 2) and 46% (for segment 4) of their respective gene segments in the parental stock. They were likely contributed by one or more viruses circulating within the same area, at the same period and in the same or a sympatric host species. The minority sub-populations of segments 3, 4, and 5 became extinct upon viral passage in swine cells, whereas the minority sub-populations of segments 2, 7 and 8 completely replaced their majority counterparts. The swine cell-passaged virus was therefore a three-segment reassortant and also harboured point mutations in segments 3 and 4. The passaged virus was more homogenous than the parental stock, with only 17 minority single nucleotide polymorphisms present above 5% frequency across the whole genome. Though limited here to one sample, this deep sequencing approach highlights the evolutionary versatility of influenza viruses whereby they exploit their genetic diversity, predilection for mixed infection and reassortment to adapt to a new host environmental niche.
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http://dx.doi.org/10.1016/j.meegid.2013.04.034DOI Listing
August 2013

Microbial ecology of the rumen evaluated by 454 GS FLX pyrosequencing is affected by starch and oil supplementation of diets.

FEMS Microbiol Ecol 2013 Feb 8;83(2):504-14. Epub 2012 Oct 8.

Université de Toulouse INPT ENVT, UMR1289 Tissus Animaux Nutrition Digestion Ecosystème et Métabolisme, Toulouse, France.

To provide a comprehensive examination of the bacterial diversity in the rumen content of cows fed different diets, high-throughput 16S rRNA gene-based pyrosequencing was used. Four rumen fistulated nonlactating Holstein cows received 12 kg of dry matter per day of four diets based on maize silage during four periods: the low-starch diet (22% starch, 3% fat); the high-starch diet, supplemented with wheat plus barley (35% starch, 3% fat); the low-starch plus oil diet, supplemented with 5% of sunflower oil (20% starch, 7.6% fat) and the high-starch plus oil diet (33% starch, 7.3% fat). Samples were taken after 12 days of adaptation, 5 h postfeeding. Whatever the diet, bacterial community of sieved rumen contents was dominated by Firmicutes and Bacteroidetes. Lachnospiraceae, Ruminococcaceae, Prevotellaceae, and Rikenellaceae families were highly present and were clearly affected by cow diet. The highest abundance of Prevotellaceae and the lowest abundance of Ruminococcaceae and Rikenellaceae were found with the high-starch plus oil diet. Dietary starch increased the relative abundance of only three genera: Barnesiella, Oribacterium and Olsenella, but decreased the relative abundances of several genera, with very significant effects for Rikenellaceae_RC9 and Butyrivibrio-Pseudobutyrivibrio. Oil alone had a limited effect, but interestingly, starch plus oil addition differently affected the bacterial populations compared to starch addition without oil.
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http://dx.doi.org/10.1111/1574-6941.12011DOI Listing
February 2013

NG6: Integrated next generation sequencing storage and processing environment.

BMC Genomics 2012 Sep 9;13:462. Epub 2012 Sep 9.

Plate-forme bio-informatique Genotoul, INRA, Biométrie et Intelligence Artificielle, BP 52627, 31326, Castanet-Tolosan Cedex, France.

Background: Next generation sequencing platforms are now well implanted in sequencing centres and some laboratories. Upcoming smaller scale machines such as the 454 junior from Roche or the MiSeq from Illumina will increase the number of laboratories hosting a sequencer. In such a context, it is important to provide these teams with an easily manageable environment to store and process the produced reads.

Results: We describe a user-friendly information system able to manage large sets of sequencing data. It includes, on one hand, a workflow environment already containing pipelines adapted to different input formats (sff, fasta, fastq and qseq), different sequencers (Roche 454, Illumina HiSeq) and various analyses (quality control, assembly, alignment, diversity studies,…) and, on the other hand, a secured web site giving access to the results. The connected user will be able to download raw and processed data and browse through the analysis result statistics. The provided workflows can easily be modified or extended and new ones can be added. Ergatis is used as a workflow building, running and monitoring system. The analyses can be run locally or in a cluster environment using Sun Grid Engine.

Conclusions: NG6 is a complete information system designed to answer the needs of a sequencing platform. It provides a user-friendly interface to process, store and download high-throughput sequencing data.
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http://dx.doi.org/10.1186/1471-2164-13-462DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3444930PMC
September 2012

Field monitoring of avian influenza viruses: whole-genome sequencing and tracking of neuraminidase evolution using 454 pyrosequencing.

J Clin Microbiol 2012 Sep 20;50(9):2881-7. Epub 2012 Jun 20.

Universite de Toulouse, INP, ENVT, Toulouse, France.

Adaptation of avian influenza viruses (AIVs) from waterfowl to domestic poultry with a deletion in the neuraminidase (NA) stalk has already been reported. The way the virus undergoes this evolution, however, is thus far unclear. We address this question using pyrosequencing of duck and turkey low-pathogenicity AIVs. Ducks and turkeys were sampled at the very beginning of an H6N1 outbreak, and turkeys were swabbed again 8 days later. NA stalk deletions were evidenced in turkeys by Sanger sequencing. To further investigate viral evolution, 454 pyrosequencing was performed: for each set of samples, up to 41,500 reads of ca. 400 bp were generated and aligned. Genetic polymorphisms between duck and turkey viruses were tracked on the whole genome. NA deletion was detected in less than 2% of reads in duck feces but in 100% of reads in turkey tracheal specimens collected at the same time. Further variations in length were observed in NA from turkeys 8 days later. Similarly, minority mutants emerged on the hemagglutinin (HA) gene, with substitutions mostly in the receptor binding site on the globular head. These critical changes suggest a strong evolutionary pressure in turkeys. The increasing performances of next-generation sequencing technologies should enable us to monitor the genomic diversity of avian influenza viruses and early emergence of potentially pathogenic variants within bird flocks. The present study, based on 454 pyrosequencing, suggests that NA deletion, an example of AIV adaptation from waterfowl to domestic poultry, occurs by selection rather than de novo emergence of viral mutants.
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http://dx.doi.org/10.1128/JCM.01142-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3421805PMC
September 2012

Metabolic adaptation to a high-fat diet is associated with a change in the gut microbiota.

Gut 2012 Apr 22;61(4):543-53. Epub 2011 Nov 22.

Institut National de la Santé et de la Recherche Médicale, Toulouse, France.

Objective: The gut microbiota, which is considered a causal factor in metabolic diseases as shown best in animals, is under the dual influence of the host genome and nutritional environment. This study investigated whether the gut microbiota per se, aside from changes in genetic background and diet, could sign different metabolic phenotypes in mice.

Methods: The unique animal model of metabolic adaptation was used, whereby C57Bl/6 male mice fed a high-fat carbohydrate-free diet (HFD) became either diabetic (HFD diabetic, HFD-D) or resisted diabetes (HFD diabetes-resistant, HFD-DR). Pyrosequencing of the gut microbiota was carried out to profile the gut microbial community of different metabolic phenotypes. Inflammation, gut permeability, features of white adipose tissue, liver and skeletal muscle were studied. Furthermore, to modify the gut microbiota directly, an additional group of mice was given a gluco-oligosaccharide (GOS)-supplemented HFD (HFD+GOS).

Results: Despite the mice having the same genetic background and nutritional status, a gut microbial profile specific to each metabolic phenotype was identified. The HFD-D gut microbial profile was associated with increased gut permeability linked to increased endotoxaemia and to a dramatic increase in cell number in the stroma vascular fraction from visceral white adipose tissue. Most of the physiological characteristics of the HFD-fed mice were modulated when gut microbiota was intentionally modified by GOS dietary fibres.

Conclusions: The gut microbiota is a signature of the metabolic phenotypes independent of differences in host genetic background and diet.
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http://dx.doi.org/10.1136/gutjnl-2011-301012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3292714PMC
April 2012

RNAspace.org: An integrated environment for the prediction, annotation, and analysis of ncRNA.

RNA 2011 Nov 23;17(11):1947-56. Epub 2011 Sep 23.

INRA, UBIA, UR 875, F-31320 Castanet-Tolosan, France.

The annotation of noncoding RNA genes remains a major bottleneck in genome sequencing projects. Most genome sequences released today still come with sets of tRNAs and rRNAs as the only annotated RNA elements, ignoring hundreds of other RNA families. We have developed a web environment that is dedicated to noncoding RNA (ncRNA) prediction, annotation, and analysis and allows users to run a variety of tools in an integrated and flexible manner. This environment offers complementary ncRNA gene finders and a set of tools for the comparison, visualization, editing, and export of ncRNA candidates. Predictions can be filtered according to a large set of characteristics. Based on this environment, we created a public website located at http://RNAspace.org. It accepts genomic sequences up to 5 Mb, which permits for an online annotation of a complete bacterial genome or a small eukaryotic chromosome. The project is hosted as a Source Forge project (http://rnaspace.sourceforge.net/).
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http://dx.doi.org/10.1261/rna.2844911DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3198588PMC
November 2011

Assessment of replicate bias in 454 pyrosequencing and a multi-purpose read-filtering tool.

BMC Res Notes 2011 May 26;4:149. Epub 2011 May 26.

Plate-forme bio-informatique Genotoul, INRA, Biométrie et Intelligence Artificielle/Génétique Cellulaire, BP 52627, 31326 Castanet-Tolosan Cedex, France.

Background: Roche 454 pyrosequencing platform is often considered the most versatile of the Next Generation Sequencing technology platforms, permitting the sequencing of large genomes, the analysis of variations or the study of transcriptomes. A recent reported bias leads to the production of multiple reads for a unique DNA fragment in a random manner within a run. This bias has a direct impact on the quality of the measurement of the representation of the fragments using the reads. Other cleaning steps are usually performed on the reads before assembly or alignment.

Findings: PyroCleaner is a software module intended to clean 454 pyrosequencing reads in order to ease the assembly process. This program is a free software and is distributed under the terms of the GNU General Public License as published by the Free Software Foundation. It implements several filters using criteria such as read duplication, length, complexity, base-pair quality and number of undetermined bases. It also permits to clean flowgram files (.sff) of paired-end sequences generating on one hand validated paired-ends file and the other hand single read file.

Conclusions: Read cleaning has always been an important step in sequence analysis. The pyrocleaner python module is a Swiss knife dedicated to 454 reads cleaning. It includes commonly used filters as well as specialised ones such as duplicated read removal and paired-end read verification.
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http://dx.doi.org/10.1186/1756-0500-4-149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3117718PMC
May 2011