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Nicolas Schnel

Bio: Nicolas Schnel is an academic researcher from French Institute for Research in Computer Science and Automation. The author has contributed to research in topics: Ontology (information science) & Reference genome. The author has an hindex of 3, co-authored 4 publications receiving 1384 citations. Previous affiliations of Nicolas Schnel include Institut national de la recherche agronomique.

Papers
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Journal ArticleDOI
Boulos Chalhoub1, Shengyi Liu2, Isobel A. P. Parkin3, Haibao Tang4, Haibao Tang5, Xiyin Wang6, Julien Chiquet1, Harry Belcram1, Chaobo Tong2, Birgit Samans7, Margot Correa8, Corinne Da Silva8, Jérémy Just1, Cyril Falentin9, Chu Shin Koh10, Isabelle Le Clainche1, Maria Bernard8, Pascal Bento8, Benjamin Noel8, Karine Labadie8, Adriana Alberti8, Mathieu Charles9, Dominique Arnaud1, Hui Guo6, Christian Daviaud, Salman Alamery11, Kamel Jabbari1, Kamel Jabbari12, Meixia Zhao13, Patrick P. Edger14, Houda Chelaifa1, David C. Tack15, Gilles Lassalle9, Imen Mestiri1, Nicolas Schnel9, Marie-Christine Le Paslier9, Guangyi Fan, Victor Renault16, Philippe E. Bayer11, Agnieszka A. Golicz11, Sahana Manoli11, Tae-Ho Lee6, Vinh Ha Dinh Thi1, Smahane Chalabi1, Qiong Hu2, Chuchuan Fan17, Reece Tollenaere11, Yunhai Lu1, Christophe Battail8, Jinxiong Shen17, Christine Sidebottom10, Xinfa Wang2, Aurélie Canaguier1, Aurélie Chauveau9, Aurélie Bérard9, G. Deniot9, Mei Guan18, Zhongsong Liu18, Fengming Sun, Yong Pyo Lim19, Eric Lyons20, Christopher D. Town5, Ian Bancroft21, Xiaowu Wang, Jinling Meng17, Jianxin Ma13, J. Chris Pires22, Graham J.W. King23, Dominique Brunel9, Régine Delourme9, Michel Renard9, Jean-Marc Aury8, Keith L. Adams15, Jacqueline Batley11, Jacqueline Batley24, Rod J. Snowdon7, Jörg Tost, David Edwards11, David Edwards24, Yongming Zhou17, Wei Hua2, Andrew G. Sharpe10, Andrew H. Paterson6, Chunyun Guan18, Patrick Wincker1, Patrick Wincker8, Patrick Wincker25 
22 Aug 2014-Science
TL;DR: The polyploid genome of Brassica napus, which originated from a recent combination of two distinct genomes approximately 7500 years ago and gave rise to the crops of rape oilseed, is sequenced.
Abstract: Oilseed rape (Brassica napus L.) was formed ~7500 years ago by hybridization between B. rapa and B. oleracea, followed by chromosome doubling, a process known as allopolyploidy. Together with more ancient polyploidizations, this conferred an aggregate 72× genome multiplication since the origin of angiosperms and high gene content. We examined the B. napus genome and the consequences of its recent duplication. The constituent An and Cn subgenomes are engaged in subtle structural, functional, and epigenetic cross-talk, with abundant homeologous exchanges. Incipient gene loss and expression divergence have begun. Selection in B. napus oilseed types has accelerated the loss of glucosinolate genes, while preserving expansion of oil biosynthesis genes. These processes provide insights into allopolyploid evolution and its relationship with crop domestication and improvement.

1,743 citations

Book ChapterDOI
11 Oct 2010
TL;DR: It is shown that a SNP corresponds to a recognisable pattern in the de Bruijn graph built from the reads, and an approach is proposed which compares two sets of raw reads and proposes algorithms to identify these patterns, called mouths.
Abstract: Next generation sequencing (NGS) technologies are being applied to many fields of biology, notably to survey the polymorphism across individuals of a species. However, while single nucleotide polymorphisms (SNPs) are almost routinely identified in model organisms, the detection of SNPs in non model species remains very challenging due to the fact that almost all methods rely on the use of a reference genome. We address here the problem of identifying SNPs without a reference genome. For this, we propose an approach which compares two sets of raw reads. We show that a SNP corresponds to a recognisable pattern in the de Bruijn graph built from the reads, and we propose algorithms to identify these patterns, that we call mouths. We outline the potential of our method on real data. The method is tailored to short reads (typically Illumina), and works well even when the coverage is low where it reports few but highly confident SNPs. Our program, called kisSnp, can be downloaded here: http://alcovna.genouest.org/kissnp/.

44 citations

Proceedings ArticleDOI
01 Jan 2012
TL;DR: The goal of this work is to create an interactive tool that will allow a radiologist to compare any given MRI artifact image with those contained in the ontology of MRI artifacts.
Abstract: Magnetic Resonance Imaging is an essential diagnostic imaging technique. The complexity of interpreting MRI images is often compounded by the presence of a wide range of artifacts which are often challenging to identify and eliminate. Ontology permits the construction of a knowledge database with which users can interact given an appropriate interface. The goal of this work is to create an interactive tool for the ontology of MRI artifacts that will allow a radiologist to compare any given MRI artifact image with those contained in the ontology. Material and method: Using Protege 4, we have constructed the ontology with input from an expert in MRI artifacts and utilizing images exemplifying such artifacts. The graphical user interface has been built in Java and the linkage with the ontology made with Owl API. Results: Using the tool, users can compare imaging artifacts encountered in daily practice to those in the database. Once a user has identified the image the most similar to their own, they then have instantaneous access to the knowledge contained in the ontology about the artifact. Individual users can also submit images and have access to DICOM data.

2 citations


Cited by
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Journal ArticleDOI
TL;DR: Genomic signatures of selection and domestication are associated with positively selected genes (PSGs) for fiber improvement in the A subgenome and for stress tolerance in the D subgenomes, suggesting asymmetric evolution.
Abstract: Upland cotton is a model for polyploid crop domestication and transgenic improvement. Here we sequenced the allotetraploid Gossypium hirsutum L. acc. TM-1 genome by integrating whole-genome shotgun reads, bacterial artificial chromosome (BAC)-end sequences and genotype-by-sequencing genetic maps. We assembled and annotated 32,032 A-subgenome genes and 34,402 D-subgenome genes. Structural rearrangements, gene loss, disrupted genes and sequence divergence were more common in the A subgenome than in the D subgenome, suggesting asymmetric evolution. However, no genome-wide expression dominance was found between the subgenomes. Genomic signatures of selection and domestication are associated with positively selected genes (PSGs) for fiber improvement in the A subgenome and for stress tolerance in the D subgenome. This draft genome sequence provides a resource for engineering superior cotton lines.

1,221 citations

Journal ArticleDOI
TL;DR: This review surveys the current knowledge about gene duplication, including gene duplication mechanisms, the potential fates of duplicate genes, models explaining duplicate gene retention, the properties that distinguish duplicate from singleton genes, and the evolutionary impact of gene duplication.
Abstract: Ancient duplication events and a high rate of retention of extant pairs of duplicate genes have contributed to an abundance of duplicate genes in plant genomes. These duplicates have contributed to the evolution of novel functions, such as the production of floral structures, induction of disease resistance, and adaptation to stress. Additionally, recent whole-genome duplications that have occurred in the lineages of several domesticated crop species, including wheat (Triticum aestivum), cotton (Gossypium hirsutum), and soybean (Glycine max), have contributed to important agronomic traits, such as grain quality, fruit shape, and flowering time. Therefore, understanding the mechanisms and impacts of gene duplication will be important to future studies of plants in general and of agronomically important crops in particular. In this review, we survey the current knowledge about gene duplication, including gene duplication mechanisms, the potential fates of duplicate genes, models explaining duplicate gene retention, the properties that distinguish duplicate from singleton genes, and the evolutionary impact of gene duplication.

856 citations

Journal ArticleDOI
TL;DR: A draft genome using 181-fold paired-end sequences assisted by fivefold BAC-to-BAC sequences and a high-resolution genetic map is produced for G. hirsutum, revealing conserved gene order and concerted evolution of different regulatory mechanisms for Cellulose synthase and 1-Aminocyclopropane-1-carboxylic acid oxidase1 and 3 may be important for enhanced fiber production.
Abstract: Gossypium hirsutum has proven difficult to sequence owing to its complex allotetraploid (AtDt) genome. Here we produce a draft genome using 181-fold paired-end sequences assisted by fivefold BAC-to-BAC sequences and a high-resolution genetic map. In our assembly 88.5% of the 2,173-Mb scaffolds, which cover 89.6%∼96.7% of the AtDt genome, are anchored and oriented to 26 pseudochromosomes. Comparison of this G. hirsutum AtDt genome with the already sequenced diploid Gossypium arboreum (AA) and Gossypium raimondii (DD) genomes revealed conserved gene order. Repeated sequences account for 67.2% of the AtDt genome, and transposable elements (TEs) originating from Dt seem more active than from At. Reduction in the AtDt genome size occurred after allopolyploidization. The A or At genome may have undergone positive selection for fiber traits. Concerted evolution of different regulatory mechanisms for Cellulose synthase (CesA) and 1-Aminocyclopropane-1-carboxylic acid oxidase1 and 3 (ACO1,3) may be important for enhanced fiber production in G. hirsutum.

836 citations

Journal ArticleDOI
TL;DR: An efficient software implementation, Cortex, the first de novo assembler capable of assembling multiple eukaryotic genomes simultaneously is provided, and how population information from ten chimpanzees enables accurate variant calls without a reference sequence is shown.
Abstract: Gil McVean and colleagues report algorithms for de novo assembly and genotyping of variants using colored de Bruijn graphs and provide these in a software implementation called Cortex. Their methods can detect and genotype both simple and complex genetic variants in either an individual or a population.

695 citations

Journal ArticleDOI
TL;DR: A comprehensive landscape of different modes of gene duplication across the plant kingdom is identified by comparing 141 genomes, which provides a solid foundation for further investigation of the dynamic evolution of duplicate genes.
Abstract: The sharp increase of plant genome and transcriptome data provide valuable resources to investigate evolutionary consequences of gene duplication in a range of taxa, and unravel common principles underlying duplicate gene retention. We survey 141 sequenced plant genomes to elucidate consequences of gene and genome duplication, processes central to the evolution of biodiversity. We develop a pipeline named DupGen_finder to identify different modes of gene duplication in plants. Genes derived from whole-genome, tandem, proximal, transposed, or dispersed duplication differ in abundance, selection pressure, expression divergence, and gene conversion rate among genomes. The number of WGD-derived duplicate genes decreases exponentially with increasing age of duplication events—transposed duplication- and dispersed duplication-derived genes declined in parallel. In contrast, the frequency of tandem and proximal duplications showed no significant decrease over time, providing a continuous supply of variants available for adaptation to continuously changing environments. Moreover, tandem and proximal duplicates experienced stronger selective pressure than genes formed by other modes and evolved toward biased functional roles involved in plant self-defense. The rate of gene conversion among WGD-derived gene pairs declined over time, peaking shortly after polyploidization. To provide a platform for accessing duplicated gene pairs in different plants, we constructed the Plant Duplicate Gene Database. We identify a comprehensive landscape of different modes of gene duplication across the plant kingdom by comparing 141 genomes, which provides a solid foundation for further investigation of the dynamic evolution of duplicate genes.

461 citations