Publications (35)432.47 Total impact
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Dataset: FgraminearumScience
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Dataset: Science-2007-Cuomo-1400-2
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Chapter: The Ectocarpus Genome and Brown Algal Genomics (The Ectocarpus Genome Consortium)
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ABSTRACT: Brown algae are important organisms both because of their key ecological roles in coastal ecosystems and because of the remarkable biological features that they have acquired during their unusual evolutionary history. The recent sequencing of the complete genome of the filamentous brown alga Ectocarpus has provided unprecedented access to the molecular processes that underlie brown algal biology. Analysis of the genome sequence, which exhibits several unusual structural features, identified genes that are predicted to play key roles in several aspects of brown algal metabolism, in the construction of the multicellular bodyplan and in resistance to biotic and abiotic stresses. Information from the genome sequence is currently being used in combination with other genomic, genetic and biochemical tools to further investigate these and other aspects of brown algal biology at the molecular level. Here, we review some of the major discoveries that emerged from the analysis of the Ectocarpus genome sequence, with a particular focus on the unusual genome structure, inferences about brown algal evolution and novel aspects of brown algal metabolism.10/2012: pages 141-184; -
Article: Transposable sequence evolution is driven by gene context
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ABSTRACT: Transposable elements (TEs) in eukaryote genomes are quantitatively the main components affecting genome size, structure and expression. The dynamics of their insertion and deletion depend on diverse factors varying in strength and nature along the genome. We address here how TE sequence evolution is affected by neighboring genes and the chromatin status (euchromatin or heterochromatin) at their insertion site. We estimated the rates of evolution of TE sequences in Arabidopsis thaliana, and found that they depend on the distance to the nearest genes: TEs located close to genes evolve faster than those that are more distant. Consequently, TE sequences in heterochromatic regions, which are gene-poor regions, are surprisingly younger and longer than those elsewhere. We present a model of TE sequence dynamics in TE-rich genomes, such as maize and wheat, and in TE-poor genomes such as fly and A. thaliana.09/2012; -
Article: Formation of plant metabolic gene clusters within dynamic chromosomal regions.
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ABSTRACT: In bacteria, genes with related functions often are grouped together in operons and are cotranscribed as a single polycistronic mRNA. In eukaryotes, functionally related genes generally are scattered across the genome. Notable exceptions include gene clusters for catabolic pathways in yeast, synthesis of secondary metabolites in filamentous fungi, and the major histocompatibility complex in animals. Until quite recently it was thought that gene clusters in plants were restricted to tandem duplicates (for example, arrays of leucine-rich repeat disease-resistance genes). However, operon-like clusters of coregulated nonhomologous genes are an emerging theme in plant biology, where they may be involved in the synthesis of certain defense compounds. These clusters are unlikely to have arisen by horizontal gene transfer, and the mechanisms behind their formation are poorly understood. Previously in thale cress (Arabidopsis thaliana) we identified an operon-like gene cluster that is required for the synthesis and modification of the triterpene thalianol. Here we characterize a second operon-like triterpene cluster (the marneral cluster) from A. thaliana, compare the features of these two clusters, and investigate the evolutionary events that have led to cluster formation. We conclude that common mechanisms are likely to underlie the assembly and control of operon-like gene clusters in plants.Proceedings of the National Academy of Sciences 08/2011; 108(38):16116-21. · 9.68 Impact Factor -
Article: Genomic analysis of the necrotrophic fungal pathogens Sclerotinia sclerotiorum and Botrytis cinerea.
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ABSTRACT: Sclerotinia sclerotiorum and Botrytis cinerea are closely related necrotrophic plant pathogenic fungi notable for their wide host ranges and environmental persistence. These attributes have made these species models for understanding the complexity of necrotrophic, broad host-range pathogenicity. Despite their similarities, the two species differ in mating behaviour and the ability to produce asexual spores. We have sequenced the genomes of one strain of S. sclerotiorum and two strains of B. cinerea. The comparative analysis of these genomes relative to one another and to other sequenced fungal genomes is provided here. Their 38-39 Mb genomes include 11,860-14,270 predicted genes, which share 83% amino acid identity on average between the two species. We have mapped the S. sclerotiorum assembly to 16 chromosomes and found large-scale co-linearity with the B. cinerea genomes. Seven percent of the S. sclerotiorum genome comprises transposable elements compared to <1% of B. cinerea. The arsenal of genes associated with necrotrophic processes is similar between the species, including genes involved in plant cell wall degradation and oxalic acid production. Analysis of secondary metabolism gene clusters revealed an expansion in number and diversity of B. cinerea-specific secondary metabolites relative to S. sclerotiorum. The potential diversity in secondary metabolism might be involved in adaptation to specific ecological niches. Comparative genome analysis revealed the basis of differing sexual mating compatibility systems between S. sclerotiorum and B. cinerea. The organization of the mating-type loci differs, and their structures provide evidence for the evolution of heterothallism from homothallism. These data shed light on the evolutionary and mechanistic bases of the genetically complex traits of necrotrophic pathogenicity and sexual mating. This resource should facilitate the functional studies designed to better understand what makes these fungi such successful and persistent pathogens of agronomic crops.PLoS Genetics 08/2011; 7(8):e1002230. · 8.69 Impact Factor -
Article: Obligate biotrophy features unraveled by the genomic analysis of rust fungi.
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ABSTRACT: Rust fungi are some of the most devastating pathogens of crop plants. They are obligate biotrophs, which extract nutrients only from living plant tissues and cannot grow apart from their hosts. Their lifestyle has slowed the dissection of molecular mechanisms underlying host invasion and avoidance or suppression of plant innate immunity. We sequenced the 101-Mb genome of Melampsora larici-populina, the causal agent of poplar leaf rust, and the 89-Mb genome of Puccinia graminis f. sp. tritici, the causal agent of wheat and barley stem rust. We then compared the 16,399 predicted proteins of M. larici-populina with the 17,773 predicted proteins of P. graminis f. sp tritici. Genomic features related to their obligate biotrophic lifestyle include expanded lineage-specific gene families, a large repertoire of effector-like small secreted proteins, impaired nitrogen and sulfur assimilation pathways, and expanded families of amino acid and oligopeptide membrane transporters. The dramatic up-regulation of transcripts coding for small secreted proteins, secreted hydrolytic enzymes, and transporters in planta suggests that they play a role in host infection and nutrient acquisition. Some of these genomic hallmarks are mirrored in the genomes of other microbial eukaryotes that have independently evolved to infect plants, indicating convergent adaptation to a biotrophic existence inside plant cells.Proceedings of the National Academy of Sciences 05/2011; 108(22):9166-71. · 9.68 Impact Factor -
Article: Genome-wide evidence for local DNA methylation spreading from small RNA-targeted sequences in Arabidopsis.
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ABSTRACT: Transposable elements (TEs) and their relics play major roles in genome evolution. However, mobilization of TEs is usually deleterious and strongly repressed. In plants and mammals, this repression is typically associated with DNA methylation, but the relationship between this epigenetic mark and TE sequences has not been investigated systematically. Here, we present an improved annotation of TE sequences and use it to analyze genome-wide DNA methylation maps obtained at single-nucleotide resolution in Arabidopsis. We show that although the majority of TE sequences are methylated, ∼26% are not. Moreover, a significant fraction of TE sequences densely methylated at CG, CHG and CHH sites (where H = A, T or C) have no or few matching small interfering RNA (siRNAs) and are therefore unlikely to be targeted by the RNA-directed DNA methylation (RdDM) machinery. We provide evidence that these TE sequences acquire DNA methylation through spreading from adjacent siRNA-targeted regions. Further, we show that although both methylated and unmethylated TE sequences located in euchromatin tend to be more abundant closer to genes, this trend is least pronounced for methylated, siRNA-targeted TE sequences located 5' to genes. Based on these and other findings, we propose that spreading of DNA methylation through promoter regions explains at least in part the negative impact of siRNA-targeted TE sequences on neighboring gene expression.Nucleic Acids Research 05/2011; 39(16):6919-31. · 8.03 Impact Factor -
Article: Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations.
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ABSTRACT: Fungi are of primary ecological, biotechnological and economic importance. Many fundamental biological processes that are shared by animals and fungi are studied in fungi due to their experimental tractability. Many fungi are pathogens or mutualists and are model systems to analyse effector genes and their mechanisms of diversification. In this study, we report the genome sequence of the phytopathogenic ascomycete Leptosphaeria maculans and characterize its repertoire of protein effectors. The L. maculans genome has an unusual bipartite structure with alternating distinct guanine and cytosine-equilibrated and adenine and thymine (AT)-rich blocks of homogenous nucleotide composition. The AT-rich blocks comprise one-third of the genome and contain effector genes and families of transposable elements, both of which are affected by repeat-induced point mutation, a fungal-specific genome defence mechanism. This genomic environment for effectors promotes rapid sequence diversification and underpins the evolutionary potential of the fungus to adapt rapidly to novel host-derived constraints.Nature Communications 02/2011; 2:202. · 7.40 Impact Factor -
Article: Genome expansion and gene loss in powdery mildew fungi reveal tradeoffs in extreme parasitism.
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ABSTRACT: Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting that most effectors represent species-specific adaptations.Science 12/2010; 330(6010):1543-6. · 31.20 Impact Factor -
Article: The Ectocarpus genome and the independent evolution of multicellularity in brown algae.
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ABSTRACT: Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1). We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae, closely related to the kelps (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic approaches to explore these and other aspects of brown algal biology further.Nature 06/2010; 465(7298):617-21. · 36.28 Impact Factor -
Article: Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis
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ABSTRACT: The Périgord black truffle (Tuber melanosporum Vittad.) and the Piedmont white truffle dominate today’s truffle market1, 2. The hypogeous fruiting body of T. melanosporum is a gastronomic delicacy produced by an ectomycorrhizal symbiont3 endemic to calcareous soils in southern Europe. The worldwide demand for this truffle has fuelled intense efforts at cultivation. Identification of processes that condition and trigger fruit body and symbiosis formation, ultimately leading to efficient crop production, will be facilitated by a thorough analysis of truffle genomic traits. In the ectomycorrhizal Laccaria bicolor, the expansion of gene families may have acted as a ‘symbiosis toolbox’4. This feature may however reflect evolution of this particular taxon and not a general trait shared by all ectomycorrhizal species5. To get a better understanding of the biology and evolution of the ectomycorrhizal symbiosis, we report here the sequence of the haploid genome of T. melanosporum, which at ~125 megabases is the largest and most complex fungal genome sequenced so far. This expansion results from a proliferation of transposable elements accounting for ~58% of the genome. In contrast, this genome only contains ~7,500 protein-coding genes with very rare multigene families. It lacks large sets of carbohydrate cleaving enzymes, but a few of them involved in degradation of plant cell walls are induced in symbiotic tissues. The latter feature and the upregulation of genes encoding for lipases and multicopper oxidases suggest that T. melanosporum degrades its host cell walls during colonization. Symbiosis induces an increased expression of carbohydrate and amino acid transporters in both L. bicolor and T. melanosporum, but the comparison of genomic traits in the two ectomycorrhizal fungi showed that genetic predispositions for symbiosis—‘the symbiosis toolbox’—evolved along different ways in ascomycetes and basidiomycetes.Nature 03/2010; 464(7291):1033-1038. · 36.28 Impact Factor -
Article: Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis.
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ABSTRACT: The Périgord black truffle (Tuber melanosporum Vittad.) and the Piedmont white truffle dominate today's truffle market. The hypogeous fruiting body of T. melanosporum is a gastronomic delicacy produced by an ectomycorrhizal symbiont endemic to calcareous soils in southern Europe. The worldwide demand for this truffle has fuelled intense efforts at cultivation. Identification of processes that condition and trigger fruit body and symbiosis formation, ultimately leading to efficient crop production, will be facilitated by a thorough analysis of truffle genomic traits. In the ectomycorrhizal Laccaria bicolor, the expansion of gene families may have acted as a 'symbiosis toolbox'. This feature may however reflect evolution of this particular taxon and not a general trait shared by all ectomycorrhizal species. To get a better understanding of the biology and evolution of the ectomycorrhizal symbiosis, we report here the sequence of the haploid genome of T. melanosporum, which at approximately 125 megabases is the largest and most complex fungal genome sequenced so far. This expansion results from a proliferation of transposable elements accounting for approximately 58% of the genome. In contrast, this genome only contains approximately 7,500 protein-coding genes with very rare multigene families. It lacks large sets of carbohydrate cleaving enzymes, but a few of them involved in degradation of plant cell walls are induced in symbiotic tissues. The latter feature and the upregulation of genes encoding for lipases and multicopper oxidases suggest that T. melanosporum degrades its host cell walls during colonization. Symbiosis induces an increased expression of carbohydrate and amino acid transporters in both L. bicolor and T. melanosporum, but the comparison of genomic traits in the two ectomycorrhizal fungi showed that genetic predispositions for symbiosis-'the symbiosis toolbox'-evolved along different ways in ascomycetes and basidiomycetes.Nature 03/2010; 464(7291):1033-8. · 36.28 Impact Factor -
Article: Genome-wide studies highlight indirect links between human replication origins and gene regulation.
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ABSTRACT: To get insights into the regulation of replication initiation, we systematically mapped replication origins along 1% of the human genome in HeLa cells. We identified 283 origins, 10 times more than previously known. Origin density is strongly correlated with genomic landscapes, with clusters of closely spaced origins in GC-rich regions and no origins in large GC-poor regions. Origin sequences are evolutionarily conserved, and half of them map within or near CpG islands. Most of the origins overlap transcriptional regulatory elements, providing further evidence of a connection with gene regulation. Moreover, we identify c-JUN and c-FOS as important regulators of origin selection. Half of the identified replication initiation sites do not have an open chromatin configuration, showing the absence of a direct link with gene regulation. Replication timing analyses coupled with our origin mapping suggest that a relatively strict origin-timing program regulates the replication of the human genome.Proceedings of the National Academy of Sciences 11/2008; 105(41):15837-42. · 9.68 Impact Factor -
Article: Genome sequence of the metazoan plant-parasitic nematode Meloidogyne incognita
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ABSTRACT: © 2008 Nature Publishing Group. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike license. The definitive version was published in Nature Biotechnology 26 (2008): 909-915, doi:10.1038/nbt.1482. Plant-parasitic nematodes are major agricultural pests worldwide and novel approaches to control them are sorely needed. We report the draft genome sequence of the root-knot nematode Meloidogyne incognita, a biotrophic parasite of many crops, including tomato, cotton and coffee. Most of the assembled sequence of this asexually reproducing nematode, totaling 86 Mb, exists in pairs of homologous but divergent segments. This suggests that ancient allelic regions in M. incognita are evolving toward effective haploidy, permitting new mechanisms of adaptation. The number and diversity of plant cell wall–degrading enzymes in M. incognita is unprecedented in any animal for which a genome sequence is available, and may derive from multiple horizontal gene transfers from bacterial sources. Our results provide insights into the adaptations required by metazoans to successfully parasitize immunocompetent plants, and open the way for discovering new antiparasitic strategies. SCRI laboratory (V.C.B. and J.T.J.) received funding from the Scottish Government. This work benefited from links funded via COST Action 872. G.V.M. and V.L. are supported by ARC, CNRS, EMBO, MENRT and Region Rhone-Alpes. G.V.M., M.R.-R. and V.L. are also funded by the EU Cascade Network of Excellence and the integrated project Crescendo. M.-C.C. is supported by MENRT.Nature Biotechnology 08/2008; · 29.50 Impact Factor -
Article: Improved detection and annotation of transposable elements in sequenced genomes using multiple reference sequence sets.
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ABSTRACT: Transposable elements (TEs) are ubiquitous components of eukaryotic genomes that impact many aspects of genome function. TE detection in genomic sequences is typically performed using similarity searches against a set of reference sequences built from previously identified TEs. Here, we demonstrate that this process can be improved by designing reference sets that incorporate key aspects of the structure and evolution of TEs and by combining these sets with Repbase Update (RU), which is composed mainly of consensus sequences. Using the Arabidopsis genome as a test case, our approach leads to the detection of an extra 12.4% of TE sequences. These correspond to novel TE fragments as well as to the extension of TE fragments already detected by RU. Significantly, we find that TE detection could be readily optimized using only two reference sets, one containing true consensus sequences and the other mosaic sequences that capture the structural diversity of TE copies within a family.Genomics 06/2008; 91(5):467-75. · 3.02 Impact Factor -
Article: Promoter DNA hypermethylation and gene repression in undifferentiated Arabidopsis cells.
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ABSTRACT: Maintaining and acquiring the pluripotent cell state in plants is critical to tissue regeneration and vegetative multiplication. Histone-based epigenetic mechanisms are important for regulating this undifferentiated state. Here we report the use of genetic and pharmacological experimental approaches to show that Arabidopsis cell suspensions and calluses specifically repress some genes as a result of promoter DNA hypermethylation. We found that promoters of the MAPK12, GSTU10 and BXL1 genes become hypermethylated in callus cells and that hypermethylation also affects the TTG1, GSTF5, SUVH8, fimbrin and CCD7 genes in cell suspensions. Promoter hypermethylation in undifferentiated cells was associated with histone hypoacetylation and primarily occurred at CpG sites. Accordingly, we found that the process specifically depends on MET1 and DRM2 methyltransferases, as demonstrated with DNA methyltransferase mutants. Our results suggest that promoter DNA methylation may be another important epigenetic mechanism for the establishment and/or maintenance of the undifferentiated state in plant cells.PLoS ONE 02/2008; 3(10):e3306. · 4.09 Impact Factor -
Article: Discovering and detecting transposable elements in genome sequences.
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ABSTRACT: The contribution of transposable elements (TEs) to genome structure and evolution as well as their impact on genome sequencing, assembly, annotation and alignment has generated increasing interest in developing new methods for their computational analysis. Here we review the diversity of innovative approaches to identify and annotate TEs in the post-genomic era, covering both the discovery of new TE families and the detection of individual TE copies in genome sequences. These approaches span a broad spectrum in computational biology including de novo, homology-based, structure-based and comparative genomic methods. We conclude that the integration and visualization of multiple approaches and the development of new conceptual representations for TE annotation will further advance the computational analysis of this dynamic component of the genome.Briefings in Bioinformatics 12/2007; 8(6):382-92. · 5.20 Impact Factor -
Article: Evolution of genes and genomes on the Drosophila phylogeny.
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ABSTRACT: Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.Nature 12/2007; 450(7167):203-18. · 36.28 Impact Factor -
Article: Evolution of genes and genomes on the Drosophila phylogeny
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ABSTRACT: Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.Nature 11/2007; 450(7167):203-218. · 36.28 Impact Factor
Top co-authors
Top Journals
Institutions
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2010
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Station Biologique de Roscoff
Roscoff, Brittany, France
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2008–2010
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French National Institute for Agricultural Research
Paris, Ile-de-France, France -
Université Pierre et Marie Curie Paris 6
Paris, Ile-de-France, France
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2007
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Broad Institute of MIT and Harvard
Cambridge, MA, USA -
The University of Manchester
- Faculty of Life Sciences
Manchester, ENG, United Kingdom
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2003–2007
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Institut Jacques Monod
Paris, Ile-de-France, France
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