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News
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Unleashing meiotic crossovers in crops
To increase genetic recombination inactivating RECQ4 gene

During the process of sexual reproduction, chromosomes exchange genetic material by recombination (crossing-over) so participating in diversity. But shuffling is limited, exchanges being scarce, genes inhibiting this mechanism. Raphaël Mercier leader of the group "Mecanism of Meiosis", IJPB, INRA, Versailles, and other scientist of INRA and CIRAD have shown that when one of these genes: RECQ4, is desactivated, the number of recombinations is 3 fold higher in crops as rice, pea and tomatoe. That breakthrough published in Nature Plants, the 26th november 2018, could allow to speed up the selection process in plant breeding and the production of plants better adapted to environment conditions (pests resistance, climate change adaptation).

La recombinaison est un mécanisme naturel commun à tous les organismes qui pratiquent la reproduction sexuée, qu'il s'agisse des végétaux, des champignons ou des animaux. C'est ce mélange des chromosomes qui est à l'origine de la diversité génétique au sein des espèces. L'amélioration des plantes, telle qu'elle est pratiquée depuis dix mille ans, et qui consiste à croiser deux plantes choisies pour leur caractères intéressants et complémentaires afin de les réunir dans une seule, repose essentiellement sur ce mécanisme. Ainsi, pour obtenir une nouvelle variété de tomate à la fois savoureuse et résistante à un bioagresseur, on va s'efforcer de croiser et sélectionner, via les recombinaisons successives, des tomates qui possèdent les gènes impliqués dans le goût et la résistance. Mais ce processus prend beaucoup de temps, car le nombre de recombinaisons qui s'opèrent lors de la reproduction est faible. En moyenne, il ne se crée qu'un à trois points d'échanges de matériel génétique, ou crossing-over, entre les chromosomes par croisement. Pour cette raison, il est impossible par exemple, de combiner six gènes d'intérêt en une seule génération, ce qui constitue un frein important à l'amélioration des variétés.

Mais qu'est-ce qui limite ce nombre d'événements de combinaisons ?
Pour le comprendre, les chercheurs de l’INRA ont identifié et étudié chez la plante modèle Arabidopsis thaliana, les gènes impliqués dans le contrôle du niveau de recombinaison. Et ils ont découvert que l'un d'eux, RECQ4, exerce une action anti crossing-over particulièrement élevée. Au point qu'en le rendant non fonctionnel, on multiplie de deux à quatre fois la fréquence des recombinaisons !

Mais qu'en est-il sur des plantes cultivées ?
C'est ce qu'ont évalué les chercheurs, au sein d'un consortium associant l'INRA et le CIRAD, en examinant trois espèces d'intérêt agronomique, le pois, la tomate et le riz. Et c'est un succès. En "éteignant" le gène RECQ4, ils ont multiplié en moyenne par trois le nombre de crossing-over, avec pour conséquence un brassage plus important des chromosomes et donc une augmentation de la diversité, pour chaque génération. En tant qu'organisme de recherche finalisée, l'Inra va maintenant s'attacher à intégrer cet outil dans les programmes d'amélioration des plantes.

Mais pourquoi les recombinaisons sont-elles si peu fréquentes ?
Plus précisément, qu'est-ce qui explique que des mécanismes actifs, tels que le gène RECQ4, limitent ce processus, et donc le rythme de la diversité, chez l'immense majorité des organismes vivants qui se reproduisent sexuellement ? Eh bien les chercheurs n'ont pas encore la réponse. La théorie la plus partagée pour expliquer ce phénomène, c'est que l'évolution des espèces se produit dans un environnement qui est globalement plutôt stable. Par conséquent, les combinaisons sélectionnées lors des générations précédentes se révèlent bien adaptées au milieu dans lequel se développent les nouveaux individus. Or, si la diversité est indispensable à l'adaptation et la survie, rebattre l'ensemble des cartes, autrement dit bouleverser l'équilibre à chaque génération, n'est sans doute la solution la plus optimale. Bref, il faut de la diversité, mais pas trop.

Communiqué de presse INRA 26/11/18

Contact:
Raphaël Mercier (01 30 83 39 89) Institut Jean-Pierre Bourgin (INRA, AgroParisTech, ERL CNRS)

Contact(s) press:
Inra service de presse (01 42 75 91 86)
Scientific department associated:
Biologie et amélioration des plantes
Center associated:
Versailles-Grignon

Référence:
Delphine Mieulet, Gregoire Aubert, Cecile Bres, Anthony Klein, Gaëtan Droc, Emilie Vieille, Celine Rond-Coissieux, Myriam Sanchez, Marion Dalmais, Jean-Philippe Mauxion, Christophe Rothan, Emmanuel Guiderdoni and Raphael Mercier, Unleashing meiotic crossovers in crops, Nature Plants doi: https://doi.org/10.1101/343509 Abstract

See also:
Raphaël Mercier, lauréat du Laurier INRA défi scientifique 2016

26 novembre 2018



Events
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Symposium IJPB 2018

March 19-20th 2018, INRA, Versailles, France

The First Symposium IJPB will offer a chance to listen to some of the best research developed at IJPB (but only a fraction of it!) with talks from David Bouchez, Nicolas Arnaud, Hervé Vaucheret, José Jiménez-Gómez, Raphaël Mercier, Enrico Magnani, Helen North, Stéphanie Baumberger, Bertrand Hirel. Contacts

As well as talks from prestigious external invited speakers:
Thomas Greb (Heidelberg University, Germany)
Claudia Köhler (Swedish University of Agricultural Sciences, Uppsala, Sweden)
Gwyneth Ingram (ENS Lyon, France)
Yves Van de Peer (Ghent University, Belgium)
Jonathan Jones (Sainsbury Laboratory, Norwich, United Kingdom)


Anne Krapp et Olivier Loudet

Programme and flyer

Scientific Committee : Nicolas Bouché, Jasmine Burguet, Sylvie Dinant, Jean-Denis Faure, Martine Gonneau, Herman Höfte, Anne Krapp, Patrick Laufs, Loïc Lepiniec, Olivier Loudet, Céline Masclaux-Daubresse, Raphaël Mercier, Christian Meyer, Helen North et Jean-Christophe Palauqui

Organizing Committee : Corine Enard (Institut Jean-Pierre Bourgin (IJPB), Versailles), Maria-Jesus Lacruz (IJPB, Versailles), Philippe Poré (INRA, Versailles) et Stéphane Raude (IJPB, Versailles)

Contact and more information: Symposium IJPB 2018 website




Séminars
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Monday 29th January 2018
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2:00 PM

Invited Speaker
Prof. Oren OSTERSETZER-BIRAN
(Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Israel)

Plant mitochondria group II introns splicing: A window into the evolution of the nuclear spliceosomal machineries

Mitochondria serve as principal sites for cellular energy metabolism and play pivotal roles in the biosynthesis of many essential metabolites for the (plant) cell. As dependences of a free-living organism, mitochondria contain their own genome, the mtDNA. The mtDNAs in plants are notably larger and more complex in structure than their corresponding ones in Animalia. Plant mitochondria are also remarkable with respect to the presence of numerous group II introns that reside in many organellar genes. The removal of the introns from the coding sequences they interrupt is essential for respiratory functions and is mediated by enzymes that belong to a diverse set of protein-families. These include intron-encoded related proteins (i.e. maturases) that function in the splicing of group II introns in bacteria and mitochondria in fungi and plants, usually with high specificity towards the intron in which they are encoded. While the splicing of group II introns in vivo is facilitated by maturase factors, canonical group II introns are catalytic RNAs that are able to excise themselves from their pre-RNA hosts in vitro, in the absence of the protein cofactors, using a mechanism identical to that utilized by the spliceosome. Structural analyses and phylogenetic data may indicate that the spliceosomal RNAs have evolved from group II intron-related ancestors. Yet, it remains unclear how could such general players in spliceosomal splicing evolve from the monospecific bacterial systems (i.e. a group II intron RNAs and their highly specific intron-encoded maturase factors). Analysis of the organellar splicing machinery in plants may provide us with important clues into the evolution of the nuclear splicing machineries. Genetic and biochemical studies led to the identification of different protein factors that facilitate the splicing of many of the mitochondrial introns in plants. We established the native RNA targets of different maturase factors in plants and analyzed the organellar and developmental defects associated with their mutant lines in vivo. Interestingly, while model maturases in bacteria and fungi mitochondria act specifically on their cognate intron RNAs, the plant maturases are acting on multiple mtRNA targets, thus seem to be acting as organellar proto-spliceosomal factors. The ability of the mitochondrial maturases in plants to act on different intron targets further support the notion that the early organellar self-splicing and mobile group II RNAs spread in the eukaryotic genomes and later ‘degenerated’ into the universal splicing system, known as the spliceosome. The similarities between maturases and the core spliceosomal factor, Prp8, may support this intriguing hypothesis.

Oren Ostersetzer-Biran webpage

Invited by: Hakim Mireau 

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Thursday 22th March 2018
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11:00 AM
Grande salle Bât. 7
Visitor
Dr. Sichul LEE
Center of Plant Aging Research, Institute of basic science & Daegu Gyeongbuk Institute of Science and Technology,
South Corea

OsASN1 overexpression in rice increases grain protein and yield
grown under nitrogen limitation

Invited by: Céline Masclaux-Daubresse

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Friday 23th March 2018
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11:00 AM
Bibliothèque physio-phyto Bât. 2
Visitor
Prof. Kris VISSENBERG
Université d'Anvers, Belgium


Control of root hair elongation
by auxin and the ERULUS kinase in Arabidopsis thaliana

Invited by: Herman Höfte

___________________________________________________

Monday 14th May 2018
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2:00 PM

Invited speaker IJPB/SPS
Prof. Henrik JÖNSSON
The Sainsbury Laboratory, Cambridge, UK

How many cells can you fit in a stem cell niche?

Plant shoots harbor stem cells throughout the life of the plant maintained via a gene regulatory feedback network. Perturbations to these regulatory genes lead to changes in the size and shape of the stem cell niche. Similar effects can be achieved by perturbing the cell walls and heterogeneous and anisotropic mechanical wall properties need to be regulated to generate correct form. We use a Computational Morphodynamics approach, combining live imaging and models of cell wall mechanics and gene networks, to understand how growth and differentiation is coordinated. In this talk I will discuss how mechanical patterning can overlap with gene expression patterns, and how cell size and tissue size can influence the maintenance of the stem cell niche.

Hendrik Jönsson Webpage

Invited by: Jasmine Burguet & Philippe Andrey

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Monday 28th May 2018
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11:00
AM
Grande salle Bât. 7
Seminar
Prof. Frank VAN BREUSEGEM
VIB, Belgium

Oxidative Stress Signaling in Plants. Towards the proteome and beyond

In plants, alterations of reactive oxygen species (ROS) levels cause fluctuations of the redox balance and hence can affect many aspects of cellular physiology. ROS levels are controlled by a diversified set of antioxidant systems that allow the maintenance of redox status. Perturbations of these ROS levels can lead to transient or permanent changes in the redox status. This feature is exploited by plants in different stress signaling mechanisms. Understanding how plants sense ROS and transduce these stimuli into downstream biological responses is still a major challenge. Previous transcriptome-centered analyses, provided us first insights in the regulatory networks that govern the oxidative stress response. Now, tailoring various proteomics technologies allowed us to assess oxidative stress dependent changes at the posttranslational level. These efforts will allow a better understanding of how cells interpret the oxidative signals that arise from developmental cues and stress conditions.

Frank Van Breusegem Lab
Invited by:
Pierre Hilson
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Tuesday 5th June 2018
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10:00 AM-12:30 PM

Grande salle Bât. 7
Visitor
10:00 AM

Margot LECLERE
Agronomie, INRA, Thiverval-Grignon, France

On-farm assessment of innovative camelina management strategies to supply a biorefinery in Northern France

11h00 AM
Dr. Christina EYNCK
Saskatoon Research and Development Centre, Canada

Camelina breeding and research at Agriculture and Agri-Food Canada - Saskatoon
Invited by: Jean-Denis Faure

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Monday 11th June 2018
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2:00 PM

Seminar Focus
Dr. Herman HÖFTE
Team "Primary cell wall"

Cell wall sensing in plant growth and development

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Friday 15th June 2018
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11:00
AM
bibliothèque physio-phyto Bât. 2

Visitor
Dr. Alexandre MARTINIERE
Biochimie & Physiologie Moléculaire des Plantes
SupAgro, Montpellier, France

Early signalling events during osmotic stress in Arabidopsis
Invited by:
Herman Höfte

___________________________________________________

Monday 18th June 2018
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2:00
PM
Invited Speaker IJPB/SPS
Dr. Emmanuelle BAYER
Research Group Plasmodesmata mediated intercellular communication
CNRS-Université de Bordeaux, France


Plasmodesmata: cellular machine for inter and intra cellular communication

Intercellular communication is critical for multicellularity. It coordinates the activities within individual cells to support the function of an organism as a whole. Plants have developed remarkable cellular machines -the Plasmodesmata (PD) pores- which interconnect every single cell within the plant body, establishing direct membrane and cytoplasmic continuity, a situation unique to plants. PD are indispensable for plant life. They control the flux of molecules between cells and are decisive for development, environmental adaptation and defence signalling. However, how PD integrate signalling to coordinate responses at a multicellular level remains unclear.
A striking feature of PD organisation, setting them apart from animal cell junctions, is a strand of endoplasmic reticulum (ER) running through the pore, tethered extremely tight (~10nm) to the plasma membrane (PM) by unidentified “spokes”. To date, the function of ER-PM contacts at PD remains a complete enigma. We don’t know how and why the two organelles come together at PD cellular junctions.
Using a combination of proteomic approaches, biophysical/modelling methods and ultra-high resolution 3D imaging into molecular cell biology of plant cell-to-cell communication, our lab is trying to address the mechanism and function of ER-PM contacts at PD.

Emmanuelle Bayer Group Webpage
Invited by: Grégory Mouille
Affiche-Abstract

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Tuesday 19th June 2018
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11:30 AM
grande salle Bât. 7

Visitor
Dr. Chie KODERA
Signalisation Cellulaire (SiCE), Laboratoire Reproduction et Développement des Plantes (RDP)
ENS Lyon, France

From Yeast to Plant, and then…. -signaling and dynamics of the cell-
Invited by: David Bouchez

___________________________________________________

Monday 25th June 2018
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2:00 PM

Invited Speaker IJPB/SPS
Dr. Korbinian SCHNEEBERGER
Genome Plasticity and Computational Genetics
Max Planck Institut, Cologne, Germany

Phylogenetic association mapping and a simple, sequencing-based method to assess meiotic recombination landscapes

During the past years, great progress has been made in the development of association methods for GWAS or QTL mapping. However, methods to map the variation that can be found between species are still sparse. We have developed a genomics-based method for between-species (or ‘phylogenetic’) association mapping (PAM), which can find signals even in highly re-arranged genomes of different species. In my presentation, I will show how we used PAM in a panel of 47 closely-related plant species to map the genetic underpinnings of differences in the mutational profiles that we found in these species.
In the second part of my talk I will present a new method that reveals meiotic recombination landscapes in a single, sequencing experiment. Using sequencing data from ultra-long molecules extracted from hybrid pollen we can precisely estimate the location of hundreds of crossing-over events. We assess our method using a pool of recombinant plants which also have been whole-genome sequenced individually. Ultimately, we plan to use this method to phenotype recombination landscapes across our 47 plant species and use it as a trait for PAM.

Korbinian Schneeberger groupe webpage
Invité par : et

___________________________________________________

Monday 17th September 2018
_______________________________________________
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2:00 PM

Seminar
Dr. Jean COLCOMBET
IPS2, Orsay

Spatio-temporal regulation of MAPK activities in the perception of environment and stresses
Jean Colcombet group webpage

Invited by: Anne Krapp

___________________________________________________

Monday 8th October 2018
_______________________________________________
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2:00 PM

Invited Speaker IJPB/SPS
Dr. Totte NIITTYLA
Carbohydrate Metabolism and Cell Walls
Umeå Plant Science Center, Suède
Carbon for wood cell walls – new insights into the synthesis of cellulose

Forests assimilate approximately a quarter of the annual anthropogenic CO2 emissions. Most of this carbon is incorporated to wood which, together with the topsoil-bound carbon, create the main long-term terrestrial carbon sink on the planet. The majority of the woody biomass resides in the cell walls of wood fibres. Carbon for the fiber walls is derived from sucrose, which is synthesized and transported from photosynthetic tissues. Sucrose is actively imported into developing wood fibers, and once in the cytosol sucrose hydrolysis is carried out either by invertase (INV) or sucrose synthase (SUS) activity to provide carbon and energy for cell wall biosynthesis. In this talk I will present our work on understanding the structure and regulation of the metabolic pathways responsible for carbon transport and incorporation into wood. This will include our recent finding placing the little studied cytosolic INVs in a central position in wood metabolism and cellulose biosynthesis, a concept of altering cellulose microfibril properties by modifying substrate supply to cellulose biosynthesis, and recent results on the composition of cellulose synthase complex in the developing wood of aspen.

Recent publications relevant for the presentation
Totte Niittylä group webpage

Invited by: Rozenn Le Hir

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Monday 15th october 2018
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2:00 PM

Invited speaker IJPB/SPS
Prof. Agnieszka SIRKO
Institute of Biochemistry and Biophysics
Polish Academy of Sciences, Warsaw, Pologne

Identification and function of a selective autophagy cargo receptor NBR1 in plants

Autophagy is an evolutionary conserved process involved in maintaining cellular homeostasis via controlled degradation of cellular components and nutrients recycling. It is negatively regulated by the TOR (Target of Rapamycin) kinase complex, a central regulator of cellular metabolism. In plants, the process of autophagy is important in normal development as well as during various environmental stresses. Autophagy is not just a bulk degradation of cellular content but it can be highly selective due to involvement of proteins called selective autophagy cargo receptors that are able to recognize and target the autophagy cargo to the double-membrane vesicles called autophagosomes. The autophagosomes are delivered to the vacuole for degradation. Not only cargo but also the cargo receptors are degraded during this process. The first plant selective autophagy cargo receptors from the NBR1-family have been described in 2011 by two independent groups. The talk will cover data related to identification and characterization of NBR1-like proteins in plants. Next I will focus on the consequences of NBR1 overexpression in plants and discuss the links between NBR1 activity, autophagy flux and TOR signaling pathway.

Group of Agnieszka Sirko
invited by: Céline Masclaux-Daubresse

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Monday 12th november 2018
_______________________________________________
_____

2:00 PM

Visitor
Dr. Aurélien BOISSON-DERNIER
Cell Wall Integrity and Growth Control in Pollen Tubes and Root Hairs, Botanical Institute, University of Cologne, Allemagne

Cell Wall Integrity Maintenance: new molecular players and conservation during land plant evolution

Group of Aurélien Boisson-Dernier
Recent publications relevant for the presentation
Invited by:

___________________________________________________

Monday 19th november 2018
_______________________________________________
_____

2:00 PM

Invited Speaker JPB/SPS
Dr. Rodrigo A. GUTIERREZ
Plant Systems Biology Lab,Universidad Catolica de Chile, Chili

Nitrogen Regulatory Networks in Plants: From molecules to the ecosystem

Lab of Rodrigo A. Gutiérrez
Invited by:

___________________________________________________

CANCELLED
Monday 3rd december 2018

_______________________________________________
_____

2:00 PM

Invited Speaker
Prof. Junko KYOZUKA
Tohoku University, Sendai, Japon

Function of Strigolactone (SL)/KAI2-ligand signalling in Marchantia
and SL biosynthesis in M. paleacea


Junko Kyozuka webpage
Invited by
___________________________________________________

Monday 10th december 2018
_______________________________________________
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2:00 PM

Invited Speaker IJPB/SPS
Prof. Gerhard LEUBNER
The Seed Biology Place,
Royal Holloway, University of London, Egham,UK
SeedAdapt:
A tale of two seeds with distinct dormancy, dispersal, transcriptomes, hormonomes, and stress response

Gerhard Leubner webpage & Website Gerhard Leubner Lab

The aim of the SeedAdapt project (www.seedadapt.eu) is to elucidate the molecular mechanisms of fruit/seed-related early-life history traits that evolved in annual plant species as adaptations to abiotic stresses. Higher plant dispersal units - diaspores, here:fruits and seeds - support the distribution and early life history of the progeny. Our project will use a comparative approach to understand the dimorphic diaspore (fruit/seed) syndromes produced on the same plant of annual Aethionema species (sister of all core Brassicaceae, cabbage family) and provide distinct adaptations as a dormancy bet-hedging strategy. The availibility of the Aethionema arabicum genome will facilitate our comparative investigation of the epigenomes, hormonomes and transcriptomes in relation to abiotic stress during sensitive developmental processes. Prof Gerhard Leubner, lead PI of SeedAdapt, has made important discoveries in the seed biology of wild, weed and crop species.

Invited by

Affiche/Abstract
Registration compulsory except for members of INRA Versailles up to 06/12/18

___________________________________________________

Monday 17th december 2018
_______________________________________________
_____

2:00 PM

Invited Speaker IJPB/SPS
Dr. François JEROME
Catalyse et Milieux non-Conventionnels, Institut de chimie des milieux et matériaux de Poitiers
Université de Poitiers-CNRS

Catalytic conversion of lignocellulosic biomass to specialty chemicals

With the exponential growth of the world population, chemistry has to produce always more and better from less. Lignocellulosic biomass is an important source of renewable carbon from which a myriad of chemicals can be theoretically produced. In this lecture, we will discuss the potential, but also the limitations, of lignocellulosic biomass for the production of specialty chemicals, including alkyl levulinate (solvent), alkylpolyglycosides (surfactant) and aromatics (monomer). In the different sections, we will highlight the challenges faced by the chemical industry to produce bio-based chemicals not only with improved properties but also with a higher ecological footprint than the existing ones.

François Jérôme portrait

Invited by

Affiche/Abstract
Registration compulsory except for members of INRA Versailles up to 13/12/18

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Seminars location except other indications
___________________________________

Amphitheatre, Building 10
INRA Centre de Versailles-Grignon
Route de St Cyr (RD10)
F-78026 Versailles Cedex
France

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