• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 421
  • 305
  • 125
  • 46
  • 41
  • 13
  • 12
  • 12
  • 8
  • 7
  • 7
  • 7
  • 7
  • 7
  • 7
  • Tagged with
  • 1161
  • 295
  • 163
  • 128
  • 110
  • 109
  • 106
  • 105
  • 101
  • 84
  • 81
  • 77
  • 72
  • 71
  • 58
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
711

Os Grupos de Choro nos Anos 90 no Rio de Janeiro : suas Re-Leituras dos Grandes Clássicos e Inter-Relações entre Gêneros Musicais / The Choro Groups in the Nineties in Rio de Janeiro : heir new approaches to the great classics and their inter-relations with other musical genres

Zagury, Sheila, 1964- 25 August 2018 (has links)
Orientador: Antonio Rafael Carvalho dos Santos / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-25T14:14:01Z (GMT). No. of bitstreams: 1 Zagury_Sheila_D.pdf: 30979505 bytes, checksum: ce7c600191ad8121332839c65369fdce (MD5) Previous issue date: 2014 / Resumo: O presente trabalho apresenta um estudo a respeito dos grupos dedicados à música instrumental popular que surgiram no Rio de Janeiro a partir da década de 1990 e as suas contribuições musicais para o choro. Tais conjuntos buscaram inovar o fazer musical do choro, ao trazer mudanças nos arranjos de grandese clássicos do gênero assim como suas possíveis inter-relações deste com outros gêneros musicais. Tendo em vista a busca pela sua abordagem na criação e práticas musicais, selecionamos quatro representantes desta geração de conjuntos cariocas. Para contextualizar tal objeto de pesquisa, foram elaboradas compilações de significados para os termos choro, gênero e estilo musicais. A partir da observação das suas trajetórias e do seu material musical, foi possível constatar as propostas de mudança dos grupos estudados no repertório usual do choro e outras modificações, como a inserção de outros repertórios estranhos ao âmbito deste gênero, tanto nos seus arranjos como na escolha de obras que, a princípio não pertenceriam a este universo. As análises musicais, os levantamentos dos termos citados e a execução de alguns dos arranjos destes grupos, (assim como outros elaborados pela autora deste trabalho, a partir da década de 1990) fizeram com que algumas questões tomassem corpo. Assim, trouxemos discussões já travadas por vários pesquisadores a cerca de algumas representações que envolvem o choro, como o significado de "grupo de choro" e como a identidade nacional se relaciona com este universo da música instrumental brasileira. Tais reflexões colaboraram na busca de uma visão mais crítica do nosso assunto. A percepção dos processos de hibridação com outros mundos musicais e como estes foram elaborados são os resultados desse estudo. Esperamos que este venha contribuir para os estudos de análise e prática da música popular brasileira / Abcstract: This research presents a study of the groups devoted to Brazilian instrumental music that emerged in Rio de Janeiro in the 1990s and their musical contribuition to choro. Those groups had seeked to innovate musical making that evolves choro, in the form of changes within the repertoire¿s arrangements of this musical genre and also possible interactions with other genres. In search of an approach to musical creation and performance, we have made a selection of four among these ensembles. To put this subject in context, we have made an inventory for the meanings of the expression choro, and also a discussion about musical genre and style. By observing their history and musical material, it was possible to perceive their proposed changes to the standard choro repertoire and other modifications, such as the inclusion of works that are distant from the choro realm. These procedures were detected in the arrangements as well as in the groups¿ choices of repertoire, which could come from outside the choro universe. The musical analysis, the investigation of the meaning given to "choro", the musical genre and style¿s debates and the performance of some of the group¿s arrangements (as well as other arrangements written by this author the 1990s) have given rise to some issues. Discussions already underway by other researchers were brought in to our study, such as the representations that have evolved regarding choro: the meaning of "choro group" and how national identity relates to this Brazilian musical world. These considerations have aided in the search to a more critical point-of-view to this survey. Perceived hybrid procedures with other musical worlds and how they were developed are the results of this research. We hope that it will contribute to further analysis and performance studies of Brazilian popular music. / Doutorado / Praticas Interpretativas / Doutora em Música
712

Ecologie du copépode calanoïde Paracartia grani : implication dans le cycle de vie du parasite Marteilia refringens dans la lagune de Thau / Ecology of Paracartia grani (Copepoda, calanoida) : involvement in the life cycle of Marteilia refringens (Paramyxea) in Thau lagon (South of France)

Boyer, Séverine 11 December 2012 (has links)
Au cours de cette étude, le cycle de vie de Paracartia grani, un copépode calanoïde appartenant à la famille des Acartiidae, a été déterminé dans la lagune de Thau. En effet, ce copépode aurait une implication dans le cycle de vie du parasite Marteilia refringens, affectant les productions de bivalves. Un suivi bimensuel de la communauté mésozooplanctonique effectué sur deux ans à une station fixe dans la lagune a permis de déterminer que P. grani est l'espèce d'Acartiidae dominante en été. Son cycle de vie se compose de deux phases : une phase pélagique d'avril à janvier, et une phase benthique de février à début avril durant laquelle l'espèce subsiste dans le sédiment sous la forme d'œufs de diapause. L'analyse de la structure de la population (spectre de taille, contribution des stades de développement et sexe ratio) a permis de déterminer que 9 générations se succédaient pendant l'année. L'étude de l'influence de 3 paramètres environnementaux (température, salinité et concentration en chlorophylle a) sur la dynamique de ponte de l'espèce a révélé que la production d'œufs de P. grani était principalement régie par la température et que l'augmentation rapide de celle-ci au printemps permettait de déclencher l'éclosion des œufs de diapause. Le second objectif de cette étude s'est attaché à décrire la dynamique du parasite M. refringens chez P. grani et les bivalves Mytilus galloprovincialis et Ruditapes decussatus dans la lagune de Thau. Des analyses en histologie et hybridation in situ ont permis de décrire les différentes formes du parasite chez ces 3 espèces. La recherche de M. refringens par PCR chez les copépodites de P. grani a révélé la présence d'ADN de parasite de juin à novembre, période à laquelle de nouvelles moules apparaissent infectées. Les expériences de mesure de l'efficacité de rétention des différents stades de développement de P. grani par la moule ont permis de montrer que tous les stades de développement peuvent être impliqués dans le cycle de vie de M. refringens, en particulier les œufs du copépode qui ont par ailleurs présentés des résultats positifs en PCR. Notre étude a ainsi permis de préciser les interactions entre copépode, parasite et moules mais n'a pas permis d'élucider complètement le cycle de Marteilia refringens. Des questions restent posées concernant notamment les voies de transmission du parasite du copépode vers les moules et concernant l'impact potentiel du parasite sur le copépode lui-même. / In this study, the life cycle of Paracartia grani, a calanoid copepod belonging to the Acartiidae family was determined in Thau lagoon. Indeed, the copepod involvement in the life cycle of the parasite Marteilia refringens affecting the bivalves production is suspected. Mesozooplanktonic community was monitored twice a month over two years at a fixed station in the lagoon. Sampling has identified P. grani as the acartiid dominant species in summer. From April to January, the copepod is found in the water column while from February to early April it remains in the sediment as diapausing eggs. The analysis of the population structure (size spectrum, contribution of developmental stages and sex ratio) has revealed that there are 9 generations per year. The study of the influence of three environmental parameters (temperature, salinity and chlorophyll a concentration) on the dynamic nesting species indicated that P. grani egg production was mainly governed by temperature and its rapid increase in spring could trigger the hatching of diapause eggs.The second objective of this study aimed to describe the dynamics of the parasite M. refringens in P. grani, and in the bivalves Mytilus galloprovincialis and Ruditapes decussatus in the Thau lagoon. Histological and in situ hybridization analysis allowed describing the different forms of the parasite in these three species. Research of M. refringens by PCR in P. grani copepodites revealed that the parasite DNA presence in the copepod from June to November, when new mussels appeared infected. Experiments to measure the retention efficiency of the different stages of development of P. grani by mussels have shown that all developmental stages could be involved in M. refringens life cycle, especially copepod eggs that have also shown positive results by PCR. Our study has allowed clarifying interaction between copepods, parasites and mussels but not elucidate completely M. refringens life cycle. Questions remain especially regarding way of transmission of parasite from copepods to mussels and the potential impact of the parasite on the copepod itself.
713

Élaboration et caractérisation d'aérogels superisolants thermiques hybrides à base de silice et de polyuréthane / Elaboration and characterization of silica and polyurethane based thermal superinsulating hybrid aerogels

Diascorn, Noémie 18 December 2014 (has links)
Les aérogels sont des matériaux légers et mésoporeux très prometteurs en termes d'isolation thermique. Il est vraisemblable qu'ils ont un rôle majeur à jouer dans la réduction des déperditions thermiques à travers les enveloppes de bâtiment et celles des équipements électrodomestiques. Dans ce contexte, l'objectif de ce travail de thèse est de développer un matériau conciliant une conductivité thermique très faible et des propriétés mécaniques compatibles avec une utilisation dans ce secteur applicatif, via un procédé d'hybridation organique-inorganique entre un aérogel de silice superisolant mais fragile et un aérogel de polyuréthane, également très isolant mais plus résistant aux sollicitations mécaniques. Dans une première partie, des aérogels de silice et de polyuréthane très performants ont été chacun élaboré par voie sol-gel en conditions douces dans un milieu réactionnel composé principalement d'acétonitrile, puis séchés au CO2 supercritique et caractérisés en termes de structure, morphologie, texture, conductivité thermique et compression uniaxiale. Un travail sur la formulation de l'aérogel de polyuréthane a permis d'atteindre un compromis thermo-mécanique très satisfaisant (conductivité thermique de 0,018 W.m-1.K-1, module élastique de 7,8 MPa) . Les matrices minérales et organiques ont ensuite été couplées, tout d'abord sous forme de composites (0,018 W.m-1.K-1, 6,1 MPa) à partir d'un lit granulaire de silice sèche. Un procédé d'hybridation a été mis en œuvre entre les matrices de silice et de polyuréthane, comportant deux étapes successives de fonctionnalisation de la matrice de silice (co-condensation puis greffage de surface et croissance contrôlée d'un réseau organique secondaire). L'étude de l'hybride obtenu par des observations MEB et XPS a été initiée et a montré l'existence d'une interface présentant une forte cohésion entre les deux matrices. / Aerogels are light and mesoporous materials that appear very promising in terms of thermal insulation. They could play a great part in the future in the reduction of thermal losses through building and appliances envelopes. In this context, the goal of this thesis work is the development of a material combining a very low thermal conductivity and mechanical properties that are compatible with a use in this application sector, via an organic-inorganic hybridization process between a superinsulating - but fragile - silica aerogel, and a very insulating polyurethane aerogel with higher resistance to mechanical stress. In the first part, high performance silica and polyurethane aerogels have each been synthetized via a sol-gel route in mild conditions and in a reaction medium mainly consisting in acetonitrile, then dried in supercritical CO2, and characterized in terms of structure, morphology, texture, thermal conductivity and uniaxial compression. A work on the polyurethane aerogel formulation led to improved thermo-mechanical compromise (thermal conductivity 0.018 W.m-1.K-1, elastic modulus 7.8 MPa) . The mineral and organic matrixes were then coupled, at first in the form of composites (0.018 W.m-1.K-1, 6.1 MPa) based on a dry granular silica aerogel bead. An hybridization process was implemented between the silica and polyurethane phases, that included two successive steps of functionalization of the silica matrix (co-condensation followed by surface grafting and controlled growth of a secondary organic network). The obtained hybrid study was initiated via SEM and XPS analysis and showed a good cohesion at the interface between the polyurethane and the modified silica matrixes.
714

Approche in situ de la régulation des interactions arthropode-symbiote / In situ approach of the regulation of arthropod-symbiont interactions

Genty, Lise-Marie 17 December 2013 (has links)
La présence de Wolbachia dans les ovogonies assure la transmission verticale de la bactérie à la descendance de l'hôte. Cependant, nous montrons que chez l'hôte Armadillidium vulgare, l'efficacité de l'infection des descendants tient à un enrichissement en Wolbachia au cours de la maturation des ovaires et des ovocytes dû à une sélection en faveur des ovocytes infectés et/ou à l'entrée secondaire de Wolbachia dans les ovocytes en cours de maturation via l'infection des tissus somatiques. Dans ces tissus, nous avons précisé la localisation de Wolbachia au niveau cellulaire et révélé des morphotypes typiques de chaque tissu. Nous avons également observé Wolbachia chez des hôtes très inattendus; des nématodes non filaires infectant les cloportes, posant la question d'une transmission horizontale, et les A. vulgare mâles, sans qu'ils soient féminisés. Etonnamment, nous avons observé l'infection des gonades mâles dans des lignées d'hôtes chez lesquelles les femelles sont infectées de manière cryptique mais sans que leurs ovocytes ne soient infectés. Le maintien de l'infection entre les générations d'hôtes pourrait alors être dû à une transmission paternelle, inédite pour Wolbachia, ou à une capacité de transmission horizontale très efficace de la bactérie. Par immersion de tissus directement dans des broyats d'organes infectés nous avons en effet démontré que Wolbachia infecte très rapidement des cellules de novo. Les mécanismes d'entrée de Wolbachia dans les cellules sont inconnus mais en monitorant des voies métaboliques clefs de l'hôte nos résultats montrent que l'infection entraine une réponse globale des tissus et implique notamment un détournement de la voie autophagique chez l'hôte. / Wolbachia presence in oogonia ensures bacteria to be vertically transmitted to host offspring. However, in Armadillidium vulgare, we show that the proportion of infected oocytes increases in the course of both ovary and oocyte maturation to reach the transmission rate at the end of ovary maturation. This enrichment can be explained by a preferential selection of oocytes infected with Wolbachia and/or by a secondary acquisition of the bacteria by oocytes. We suspect an acquisition through infected somatic tissues. We localize Wolbachia at the cell level in these tissues and showed particular morphotypes for each tissue. We also observe Wolbachia in unexpected hosts; non filarial nematodes infecting woodlice (suggesting horizontal transmission), and in A. vulgare males (without a feminizing effect of the bacteria). We also observe lineages in which females are cryptically infected. Surprisingly, we observe infected male gonads in these lineages for which female oocytes are uninfected. The infection maintenance across host generations could be due to a paternal transmission of the bacteria (a transmission never described for Wolbachia), or due to an astonishing ability of horizontal transmission. Nevertheless, immersion of uninfected tissues in a solution of crushed infected tissues proves that Wolbachia can quickly infect new tissues. Cellular mechanisms that allow Wolbachia internalization into the cell are still unknown. Thus, we monitor key host metabolic pathways in ovaries and we denote that infection enhances a global response of the entire tissue. Additionally, Wolbachia infection especially implicates a high-jacking of the autophagic pathway.
715

Pour une littérature cyborg : l'hybridation médiatique du texte littéraire / A cyborg litterature : media hybridizations of the litterary text

Guilet, Anaïs 28 March 2013 (has links)
Notre thèse aborde sous l'angle métaphorique du cyborg, ce pan de la production littéraire contemporaine qui propose des textes dont le statut médiatique procède d'une hybridation spécifique entre l'hypermédia et le livre. Le cyborg permet de créer un parallèle entre la relation qui s'instaure actuellement entre le livre et l'hypermédia et la relation, faite de fantasmes et de craintes, que les hommes entretiennent avec les technologies qu'ils créent. La littérature cyborg ne propose pas des oeuvres au sein desquelles le livre et l'hypermédia s'opposeraient, mais des oeuvres offrant une hybridation médiatique du texte littéraire, fruit d'une rencontre matérielle tensionnelle. Les nouveaux médias doivent être perçus comme un moteur d'évolution plutôt que comme une menace. Il s'agit, en effet, pour la littérature contemporaine et le livre de relever le défi qui leur est posé. Le livre est au coeur de notre problématique. Il importe de le considérer comme un support du texte qui n'est pas neutre et qui possède ses caractéristiques et ses potentialités propres. L'apparition de nouveaux médias offre une occasion de réévaluer le livre dans sa dimension matérielle. Celui-ci n'est plus l'unique support du texte, nos pratiques quotidiennes de lecture, entre livre et écran, le prouvent... / Our thesis aims at exploring, through the cyborg metaphor, the part of the contemporary literature which produces texts that are the fruit of a hybridization between books and hypermedia. The cyborg enables us to draw a parallel between the connections that exist today between books and hypermedia, and the relationships - made up of fears and fantasies - that people have with the technologies they create. Cyborg literature does not propose works within which books and hypermedia are opposed, but works born from the reunion of two material supports, thus offering a media hybridization of the literary text. New media have to be appreciated as a motor of evolution rather than as a threat. Indeed, contemporary literary and books have to take up the challenge imposed by new media. The book is at the core of our problematic. We have to consider it as a medium for text, a medium that is not neutral and that holds its own characteristics and potential. New media offer an opportunity to reevaluate the book in its material dimension which is no longer the only medium for text: our daily reading practices, between books and screens, prove it...
716

MULTITERRITÓRIOS E ENTRECRUZAMENTOS HÍBRIDOS EMUMA EXPERIÊNCIA ARTÍSTICA IN SITU / MULTIPLE TERRITORIES AND HYBRIDS CROSSOVERS IN AN IN SITU ARTISTIC EXPERIENCE

Poll, Maria das Graças Garcia 31 March 2015 (has links)
The present Visual Poetry research about technology art envolves the multiple territories issues starting from the intersection of singular spaces, characterized by specific languages in analog and digital media, generating the reconfiguration of hybrid spaces that comes from the flows and the meetings of diverse artistic practices. Based on previous experience in artistic collectivity, linked to issues of production in art and occupation of non-institutionalized spaces in the city, the study leads to experiencing proposals in situ for a local/a depositary place of memories and experiences resulting from this trajectory. Referring to the cultural environment of the city and its history, we tried to propose the generation of a new perceptual capability for that space, through the collectivity participation, which are also relevant in this study. The installation is characterized by a temporarily displayed work. This work s presentation takes place in ephemeral and transitory space-time relation ship. The conduct of the research was based on authors as Carvalho (2005); Haesbaert (2004); Plaza (1998); Santos (1991); Cauquelin (2007); Bourriaud (2009); Barros (1998, 1999), the approach of the concepts / A presente pesquisa em Poéticas Visuais na linha de pesquisa Arte Tecnologia envolve a questão da multiterritorialidade a partir do entrecruzamento de espaços singulares, caracterizados por linguagens especificas em meios analógicos e digitais, gerando a reconfiguração de outros espaços, híbridos, que nascem dos fluxos e encontros a partir de práticas artísticas diversas. Com base em uma experiência anterior em coletivo artístico, vinculada às questões da produção em arte e da ocupação de espaços não institucionalizados na cidade, o estudo conduz à experienciação de propostas in situ para um local/lugar depositário de memórias e vivências oriundas desta trajetória. Remetendo ao ambiente cultural da cidade e sua história, buscou propor a geração de novas potencialidades perceptivas para aquele espaço, por meio da participação de uma coletividade, o que compõe, igualmente, a relevância do estudo. A instalação in situ se caracteriza por ser uma obra apresentada de forma temporária, vinculada a um lugar/local específico e único, sendo que a apresentação do trabalho se deu de forma efêmera e transitória em uma relação espaço-temporal. A condução da pesquisa esteve embasada em autores como Carvalho (2005); Haesbaert (2004); Plaza (1998); Santos (1991); Cauquelin (2007); Bourriaud (2009); Barros (1998; 1999), entre outros, para abordagem dos conceitos envolvidos.
717

Différenciation et hybridation chez trois espèces endémiques d'Armeria (Plumbaginaceae) du littoral portugais

Tauleigne Chagas Gomes, Ana C. January 2005 (has links)
Doctorat en Sciences / info:eu-repo/semantics/nonPublished
718

Improved enrichment cultivation of selected food-contaminating bacteria

Taskila, S. (Sanna) 16 November 2010 (has links)
Abstract The aim of this work was to assess and improve the enrichment cultivation of food-contaminating bacteria prior to detection by means of RNA-based sandwich hybridization assay (SHA). The examples of beer-spoiling lactic acid bacteria (LAB) and food-borne Salmonella Typhimurium were selected based on their relevance in Finnish food industry. Also universal challenges affecting on the selection of the enrichment cultivation procedure are discussed, including some potential possibilities for improved enrichment cultivation. The results of this study may therefore be used for the assessment of the efficiency of bacterial cultivation in other applications. The evaluation of the enrichment cultivation procedures prior to SHA lead to following conclusions: i) the enrichment cultivation procedure is necessary prior to rRNA-based SHA, and it directly influences the accuracy of SHA; ii) the improvement of the enrichment cultivation may allow faster recovery and growth of bacteria; iii) the improved recovery of bacteria can be achieved by reducing environmental stress factors in the enrichment culture; and iv) the growth of bacteria may be accelerated by assuring the selectivity of medium and allowing accessibility to growth factors. Several growth factors were studied by means of full factorial design and response surface modeling. Measured cell densities, as well as predicted lag-times and maximum growth rates in the bacterial cultures were used as responses. The results show that small shifts in the cultivation conditions extend the lag-time and decrease the growth rate of both LAB and Salmonella. Besides adjusting the temperature and pH, the growth of LAB was facilitated by reducing osmotic and oxidative stresses in the enrichment medium. In this study, a novel enzyme controlled glucose delivery system was used for the first time in the enrichment cultivation of food-contaminating bacteria. The glucose delivery system improved the growth of LAB in single strain cultures and in actual brewing process samples. The recovery of injured Salmonella was also enhanced by using the glucose delivery system together with selective siderophore ferrioxamine E, both in terms of reduced lag-times and increased growth rates. Based on the SHA, the adjusted BPW broth enhanced the molecular detection of heat-injured Salmonella in meat.
719

Chercheurs et praticiens dans les réseaux socio-numériques : multiplicité des formes de médiation en information-documentation / Researchers and practitioners in social digital networks : multiplicity of mediation forms in information-documentation

Marouki, Maryem 30 September 2013 (has links)
Les technologies de l'information et de la communication se sont largement diffusées et transformées. Elles contribuent aux évolutions des relations sociales et des modes de collaboration. Il s'agit ici d'explorer les reconfigurations des technologies et de leurs modes d'insertion et d'utilisation par les chercheurs et les praticiens dans le secteur des sciences de l’information et de la communication. Notre objectif est d’identifier le type de communication scientifique au sein des communautés virtuelles de praticiens et de chercheurs dans le domaine des sciences humaines et sociales. Les données qualitatives recueillies sur la base d’une observation ethnographique sont destinées à un traitement analytique et interprétatif. Dans le prolongement, nous cherchons à avoir une vision plus spécifique du mode de fonctionnement d’une communauté virtuelle. En effet, si les pratiques d’information des internautes sont de plus en plus au cœur des recherches, l’échange d’informations, et notamment son degré d’interaction entre les différentes sphères, sont, en revanche, nettement moins analysés dans les travaux français. Enfin, en prenant en compte ces spécificités plurielles de l’information en ligne, et en transposant des questionnements autour de la médiation, cette recherche rejoint une interrogation plus globale sur les hybridations au sein des réseaux socio numériques / The information and communication technologies have been widely disseminated and transformed. They contribute to social relations and collaboration modes changes. Here, the aim is to explore the technologies reconfiguration and their integration patterns and use by researchers and practitioners in the field of information and communication sciences. The purpose is to identify scientific communication type in virtual communities of practitioners and researchers in humanities and social sciences. Qualitative approach based on a participant-observation is intended for analytical and interpretive treatment. We try to have a more specific view of a virtual community operating mode. While the researches of information practice of Internet users are increasing, exchange of information including the degree of interaction between the different spheres are, however, much less analyzed in French work. Finally, taking into account the specificities of the plural online information and by transposing questions about mediation, this research joins a broader questioning of the hybridizations in digital social networks.
720

Expression spatio-temporelle de deux protéines PR du grain de raisin - dégradation au cours de l'infection par Botrytis cinerea - / Spatio-temporal study of two PR-proteins of grape berries -degradation during infection by Botrytis cinerea-

Colas, Steven 28 November 2012 (has links)
L'infection des baies de raisin par le champignon Botrytis cinerea, responsable de la pourriture grise, est fréquente et occasionne des dégâts importants. Pourtant, il semble que la baie dispose de moyens de défense parmi lesquels des protéines PR "Pathogenesis-Related". Chez le Pinot Noir, une chitinase (CHI4D) et une thaumatin-like (TL3) s'accumulent naturellement en grande quantité à partir de la véraison et présentent une activité antifongique contre B. cinerea in vitro. L'objectif de ce travail est de comprendre comment B. cinerea peut se développer sur des baies censées disposer de défenses suffisantes. Pour cela, l'expression spatio-temporelle des ARNm et des protéines CHI4D et TL3 a été suivie respectivement par hybridation in situ et immunohistolocalisation dans les baies, au cours de la maturation, à la suite d'un stress abiotique (UV-C) ou d'un stress biotique (B. cinerea). Dans des baies avant véraison (vertes), n'exprimant naturellement que très faiblement CHI4D et TL3, les ARNm et les protéines s'accumulent en grande quantité après application d'un stress abiotique (UV-C) ou biotique (infection artificielle par B. cinerea). Les protéines CHI4D et TL3 sont localisées au niveau des faisceaux conducteurs ainsi qu'au niveau des tissus proches des sites d'exposition aux UV-C (exocarpe) ou au niveau des sites d'inoculation de B. cinerea, suggérant qu'elles sont impliquées dans la défense de la baie avant véraison. Après véraison, les ARNm et les protéines sont naturellement accumulés au niveau de l'exocarpe et des faisceaux conducteurs qui correspondent à des sites potentiels d'entrée ou de propagation des agents pathogènes. Alors que l'application d'un stress UV-C sur ces baies ne provoque qu'un effet mineur sur l'expression de CHI4D et de TL3, au cours de l'infection par B. cinerea, les quantités de transcrits et de protéines diminuent. A un stade précoce d'infection, la diminution de la quantité des deux protéines est observée en avant du front de propagation du champignon, suggérant une dégradation par des protéases sécrétées par B. cinerea. A un stade d'infection plus avancé, cette diminution s'étend à l'ensemble de la baie. La production hétérologue des protéines CHI4D et TL3 nous a permis de confirmer que CHI4D pouvait être dégradée par des protéases aspartiques sécrétées par B. cinerea. La dégradation de TL3 n'a pas pu être reproduite in vitro. Des tests antigerminatifs effectués in vitro avec les protéines hétérologues n'ont pas permis de mettre en évidence d'effet antifongique malgré la présence d'une activité chitinase pour CHI4D et β-1,3,-glucanase pour TL3. Il est donc possible que ces protéines possèdent des fonctions autres que celles impliquées dans la défense. / Grape berries infection by the phytopathogenic fungus Botrytis cinerea, the causal agent of gray mold, is quite common and causes significant damage. However, it seems that berries have a mechanism of defense, among which are pathogenesis related proteins. In Pinot Noir grape berries, a chitinase (CHI4D) and a thaumatin-like (TL3) protein naturally accrue in large amounts from véraison and show in vitro an antifungal effect against B. cinerea. The aim of this work was to understand how B. cinerea can develop on grape berries that seem to have sufficient defense mechanisms. To do so, the spatio-temporal expression of CHI4D and TL3 mRNAs and proteins in berries was studied respectively by in situ hybridization and immunohistolocalization during maturation, after an abiotic stress (UV-C) or a biotic stress (B. cinerea). Before véraison (green berries) while the expression of CHI4D and TL3 is naturally low, mRNAs and proteins have accumulated in large amounts in berries after UV-C exposition or artificial infection with B. cinerea. CHI4D and TL3 proteins have accumulated around vascular bundles as well as near the sites of UV-C exposition (exocarp) or B. cinerea inoculation, suggesting that before véraison these proteins could be involved in the berry defense. After veraison, mRNAs and proteins naturally accumulate in the exocarp and around vascular bundles that correspond to potential sites of penetration or propagation of pathogenic agents. While the application of UV-C stress on these berries causes only a minor effect on the expression of CHI4D and TL3, during infection by B. cinerea, the amounts of mRNA and proteins decreased. At an early stage of infection, the less amounts of both proteins were observed around the fungus propagation area, suggesting that these proteins could be degraded by B. cinerea secreted proteases. At a more advanced stage of infection, the decrease extended to the entire berry.Production of heterologous CHI4D and TL3 proteins allowed us to confirm that CHI4D could be degraded by aspartic proteases secreted by B. cinerea whereas no degradation of TL3 could be observed in vitro. Both heterologous proteins showed no antifungal effect while a chitinase and a β-1,3-glucanase activities were observed respectively for CHI4D and TL3. It is therefore possible that these proteins have other functions than those involved in the defense.

Page generated in 0.0223 seconds