Thesis (Ph. D.)--University of Wisconsin--Madison, 1954. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 79-80).

Submitted by Priscila Nascimento (pnascimento@icict.fiocruz.br) on 2012-11-30T12:31:09Z No. of bitstreams: 1 beatriz-cyranka.pdf: 1720638 bytes, checksum: c436adb348584d5a5a8213fccdef6ea6 (MD5) / Made available in DSpace on 2012-11-30T12:31:09Z (GMT). No. of bitstreams: 1 beatriz-cyranka.pdf: 1720638 bytes, checksum: c436adb348584d5a5a8213fccdef6ea6 (MD5) Previous issue date: 2011 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil. / Novas tecnologias, como o sistema isolador para ensaios de esterilidade vieram a contribuir com a incorporação de um melhor desempenho destes ensaios no controle de qualidade das indústrias farmacêuticas.Este trabalho teve como objetivo a verificação do processo de biodescontaminação dentro do sistema isolador de Bio-Manguinhos, utilizado como agente esterilizante o gás de peróxido de hidrogênio. Foram utilizadas como biocarga para redução de contaminação microbiológica três concentrações dos microrganismos, Candida albicansATCC 10231, Clostridium sporogenesATCC 11437 eMicrococcus luteusATCC 9341, impregnadas em discos de filtro de celulose. Os estudos de cinética de crescimento dos microrganismos foram realizados para um melhor entendimento do seumetabolismo, bem como aspectos gerais de crescimento que contribuíram para ressaltar que a Candida albicans inicia sua fase exponencial de crescimento na segunda hora do cultivo e finaliza esta etapa na sexta hora do cultivo, com produção máxima de células viáveis, fato observado também no microrganismo Micrococccus luteus. Para o cultivo doClostridium sporogenes o crescimento foi mais lento com uma curva de crescimento com 60 horas de cultivo total. A produção de maior número de células para o Clostridiumfoi alcançada na vigésima quarta hora de cultivo, assim como a maior produção de esporos. Foi estabelecida, ao longo da curva de crescimento, a relação entre densidade ótica e número de células viáveis, relação essa importante para o estabelecimento das condições do estudo em relação à biocarga empregada de cada microrganismo no momento do desafio no sistema isolador. A capacidade de descontaminação avaliada dentro do sistema isolador com o biocida peróxido de hidrogênio revelou o tempo de exposição ao gás de 10 minutos, como resultado final satisfatório apresentando redução total da carga microbiana com destruição total das células viáveis, assim como as formas esporuladas do Clostridium sporogenes. Desta forma conclui-se que o peróxido de hidrogênioé um biocida de eficácia comprovada, nas variáveis deste estudo e o processode descontaminação no sistema isolador de Bio-Manguinhos é compatível comsua atividade finalística na produção de insumos para a saúde. / New technologies such as isolator system for sterility tests came to help with the incorporation of a better performance of these kinds of tests in quality control of pharmaceutical companies. This study aimed to verify the decontamination process within the system isolator of Bio-Manguinhos, usinghydrogen peroxide gas as a sterilizing agent. Three concentrations of microorganisms were used as bioburden for the microbiological contamination reduction, Candida albicansATCC 10231, Clostridium sporogenesATCC 11437 and Micrococcus luteusATCC 9341, impregnated in cellulose filter discs. Studies of growth kinetics of microorganisms were carried out to a better understanding of theirmetabolism, as well as general aspects of growth that contributed to emphasize that the Candida albicansbegins its exponential growth phase in the second hour of cultivation and this step ends at the sixth hour cultivation, with maximum yield of viable cells, this was also observed in the Micrococcus luteusmicroorganism. For the Clostridium sporogenescultivation, growth was slower with a 60 hours growth curve of total culture. The production of more cells for Clostridiumwas achieved in the twenty-fourth hour of cultivation, as well as the maximum spores production. It was established along the growth curve the relationship between optical density and numberof viable cells, this relationship was important to establish the conditions of the study related to the bioburden of each microorganism used to challenge the isolator system. The decontamination capacity evaluated within the isolator system with the hydrogen peroxide biocide showed that the gas exposure time of 10 minutes wassatisfactory demonstrating total reduction of the microbial load with total destruction of viable cells, as well as the sporulated forms of Clostridium sporogenes. Thus it is concluded that hydrogen peroxide is a proved effective biocide, in the variables of this study and decontamination process in the Bio-Manguinhos insulator system is compatible with its main activity in the production of health supplies.

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-22T13:29:20Z No. of bitstreams: 0 / Made available in DSpace on 2017-11-22T13:29:20Z (GMT). No. of bitstreams: 0 / Diabrotica speciosa (Germar, 1824), causa danos diretos por alimentação e indiretos como vetor de vírus para diversos grupos de plantas. A principal forma de controle são os agroquímicos, portanto visando o manejo populacional sem impacto ambiental, o presente trabalho teve como objetivo determinar a dose de radiação gama que proporciona a esterilidade de machos, o seu consumo foliar e as alterações histológicas em suas gônadas. Os adultos foram submetidos à radiação gama (60Co) no terceiro dia após a emergência nas doses de 0, 25, 50, 75 e 100 Gy a uma taxa de 0,808 KGy/hora, totalizando 20 repetições/ dose. A dose esterilizante baseou-se na fertilidade de fêmeas sexualmente maduras acasaladas por machos irradiados. Os casais foram individualizados em \"arenas\" e alimentados com folíolos de feijão (Phaseolus vulgaris L.) com gaze preta umedecida para oviposição. Os ovos foram tratados e dispostos em recipientes plásticos forrados com papel de filtro. Após a eclosão, as larvas foram transferidas para um recipiente maior com tampa telada contendo vermiculita fina e plântulas de milho (Zea mays L.) que foram substituídas a cada 10 dias, até a emergência do adulto. Após o 4º dia de irradiação disponibilizou-se um disco foliar de 3,2 cm de diâmetro por 24 horas, para cada casal. Os discos foram digitalizados e analisados no software ImageJ. Para avaliação das gônadas foram utilizados 3 machos por dose com 8 dias de idade dissecados em PBS e através da técnica de Hematoxilina Eosina as laminas foram avaliadas em microscópio óptico. Verificou-se que a esterilidade dos machos ocorreu a partir de 75 Gy e sua longevidade média foi de 12,5 dias. O consumo da área foliar dos casais constituídos por um macho estéril foi de 42,9% e a analise histológica testicular demonstrou desorganização nos tecidos e lacunas entre as células germinativas nas maiores doses de 75 Gy e 100 Gy. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Sur la base des travaux de Simone de Beauvoir Deuxième sexe I et Deuxième sexe II, et d’autres articles importants, une analyse sur la condition et la conception des femmes dans Les Soleils des indépendances a été effectuée dans le but d’étudier l’image de la femme postcoloniale africaine en général, et ivoirienne en particulier comparativement à celle d’avant l’indépendance. En examinant les conditions de la femme dans Les Soleils des indépendances d’Ahmadou Kourouma nous nous sommes retrouvés confrontés à certaines idées telles que la soumission, la société patriarcale, la femme traditionnelle, la femme moderne, la liberté, la femme comme mère mais aussi comme objet et victime des atrocités liées aux coutumes et traditions. Malgré l’accession de la Côte d’Ivoire à l’indépendance cette condition n’a pas été améliorée, et c’est ce que l’auteur dénonce indirectement et peut-être inconsciemment. / Based on Simone de Beauvoir’s work The Second Sex, and other important articles, an analysis of the condition and conception of women was carried out in order to study the image of the postcolonial African women in general, and Ivorian in particular, in comparison with the women before the independence. Through the analyse of the condition of women in Ahmadou Kourouma’s The Suns of Independence, we came across ideas such as submission, patriarchal society, traditional woman, modern woman, freedom, women as mothers but also women as sexual objects and victims of customs and traditions related atrocities. Despite the accession of Ivory Coast to independence this condition has not improved, and this is what Kourouma is indirectly or maybe unconsciously denouncing.

Abstract Demographic history and selection affect patterns of genetic diversity in nature. Timing of growth, reproduction and dormancy are important traits targeted by natural selection, because they are crucial for survival of plants growing in boreal and temperate climates, as reproduction must occur when conditions are favorable and in outcrossing plants it must be synchronized to assure pollination. In addition to adaptation to local environments, evolutionarily diverged populations may contain genomic incompatibilities that result in sterile hybrids in crosses between populations. In several plant families within population crosses can also lead to male sterile progeny, because of conflict between maternally and bi-parentally inherited genomes. In this thesis I used DNA-sequence data to estimate the demographic history of nine Arabidopsis lyrata populations and present genetic variation in some key flowering time genes, evolution of which natural selection has shaped. By crossing experiments I explored genetics of reproductive fitness in hybrids between divergent populations. I found that local climatic conditions have resulted in directional selection in addition to the demographic effects of bottlenecks during colonization events. Flowering time genes have reduced diversity compared to reference loci, which indicates selective sweeps. Selection on nucleotide variation in flowering time genes was found in Scandinavian and Icelandic populations that can be explained by selective sweeps at flowering genes when these populations colonized northern habitats after the last glacial maximum. Cryptic cytoplasmic male sterility was found in a Norwegian population, for which North Carolinian population did not have fertility restorers. It was confirmed that there is only one fertility restorer locus, the genomic location of which was mapped to a 600 kb interval at the top of chromosome two. / Tiivistelmä Populaatioiden levittäytymishistoria ja luonnonvalinta vaikuttavat geneettiseen monimuotoisuuteen ja sen vaihteluun genomin eri osissa. Kukkimisen ja kasvun päättämisen ajoitus ovat tärkeitä luonnonvalinnan kohteena olevia ominaisuuksia, sillä ne ovat välttämättömiä kasvien selviytymiselle lauhkeissa ja pohjoisissa ilmastoissa. Paikallisiin olosuhteisiin sopeutumisen lisäksi populaatioiden erilaistuminen voi johtaa genomisiin yhteensopimattomuuksiin, joiden vuoksi populaatioiden väliset risteymät ovat lisääntymiskyvyttömiä. Monilla kasvisuvuilla myös populaation sisäiset risteytykset voivat johtaa koirassteriileihin jälkeläisiin johtuen konfliktista vain äidin puolelta ja molemmilta vanhemmilta periytyvien genomien välillä. Tässä väitöskirjassa selvitän DNA-sekvenssimuunteluun perustuen yhdeksän idänpitkäpalkopopulaation demografista eli levittäymis- ja populaatiorakennehistoriaa sekä luonnonvalinnan osuutta kukkimisaikaan vaikuttavien geenien evoluutiossa. Risteytyskokeiden avulla tutkin erilaistuneiden populaatioiden risteymäjälkeläisiä selvittääkseni niiden lisääntymiskelpoisuutta ja siihen vaikuttavia geenejä. Geneettinen muuntelu kukkimisgeeneissä oli vähäisempää kuin vertailugeeneissä, joka on merkki kukkimisgeeneihin kohdistuneesta suuntaavasta valinnasta. Kukkimisgeeneihin kohdistuvaa valintaa löytyi eniten skandinaavisista ja islantilaisesta populaatiosta, mikä on selitettävissä niihin kohdistuneella suuntavalla valinnalla aikana, jolloin kasvit levittäytyivät jääkauden jälkeen pohjoisiin elinympäristöihin. Norjalaisesta populaatiosta löytyi piilevä sytoplasminen koirassteriliteetti, jolle Pohjois-Carolinan populaatiolla ei ollut hedelmällisyyden palauttavia geenejä. Tutkimus vahvisti, että hedelmällisyyden palauttaa yksi geeni, joka sijaitsee 600 000 emäsparin kokoisella alueella kromosomin kaksi alkupäässä.

Les inflorescences de riz sont sensibles au froid et à la chaleur ce qui se traduit par une stérilité des épillets à floraison. Ce n'est cependant pas directement la température de l'air qui est en cause mais la température des tissus à des stades de développement précis. Les stratégies pour faire face au stress thermique sont : 1) la tolérance physiologique d'une variété particulière; 2) l'échappement temporel au stress par l'ajustement de la phénologie et de l'heure de l'anthèse (TOA); 3) l'évitement du stress par le microclimat généré par la culture. Cette thèse a pour but de caractériser l'effet des composantes climatiques sur 2) et 3), et pour ce, le même essai a été mené au champ sur quatre variétés de riz irrigué cultivées dans quatre environnements climatiques contrastés (Philippines, 2 saisons aux Sénégal, France). Bien que peu de différences variétales aient été observées au sein de chaque site, il existe une grande variabilité de l'heure de l'anthèse et de la différence de température (TD) entre panicule (Tp) et air (Tair) en réponse à l'environnement. La durée de l'anthèse est stable et limitée à environ 2 heures par jour, alors que l'heure de l'anthèse varie de 3.4 à 6.75 heure solaire. Au moment de l'anthèse, TD observée varie entre +2 et -9.5°C. TOA et TD sont principalement caractérisés par Tair et VPD (Vapour Pressure Deficit) observés antérieurement (TOA) ou pendant (TD) l'anthèse. De plus, il existe une corrélation significative entre la stérilité (chaud ou froid) observée à maturité et Tp aux stades sensibles. Ces résultats montrent qu'en termes de risque de stérilité paniculaire pour le riz irrigué à floraison, un climat moyennement chaud et humide est plus dangereux qu'un climat très chaud mais sec car un fort VPD favorise la transpiration de la canopée et des panicules. TOA et TD ont ensuite été intégrés au modèle de culture RIDEV V.2 (qui prédit la stérilité) et les simulations de TD ont été comparées aux résultats d'un autre modèle de Tp (IM2PACT) développé indépendamment au Japon. Ces deux modèles s'avèrent robustes, et de futures collaborations mèneront à une validation complète de chaque modèle voire une intégration de ceux-ci à un nouvel outil en vues d'étudier l'impact des changements climatiques sur les cultures.Les résultats de cette étude permettront dans un futur proche 1) d'aider les sélectionneurs en apportant de nouveaux traits d'intérêts, et 2) de définir un zonage des territoires à haut risque de stress thermique pour le riz irrigué, pour des scénarios climatiques actuels et anticipés. Des études complémentaires seront nécessaires pour permettre l'application de cette approche aux systèmes non irrigués. / At the reproductive stage, rice spikelets are sensitive to cold and to heat which can lead to spikelet sterility. However, it is not the air temperature but the temperature of the sensitive organ itself during some specific sensitive stages that is involved. There are three different strategies to cope with thermal stress: 1) physiological tolerance of a particular variety; 2) temporal escape of the stress thanks to phenology and time of day of anthesis (TOA) adjustments; 3) stress avoidance through microclimate generated by crop architecture and transpiration. This PhD aims to characterize the effect of environment on 2) and 3) and to attain this goal, the same experiment was conducted with four rice varieties irrigated and grown in four different climatic environments (Philippines, Senegal two seasons, France). Even though few varietal differences were observed within a site, a great variability of TOA and difference of temperature (TD) between panicle (Tp) and air (Tair) exists in response to the environment. Anthesis duration is stable and limited to 2 hours per day, whereas time of onset of anthesis varied between 3.4 to 6.75 hours after sunrise. During anthesis, observed TD varied between +2.5 and -9.5°C. TOA and TD are mostly explained with Tair and VPD (Vapour Pressure Deficit) observed before (TOA) or during (TD) anthesis. A significant correlation between spikelet sterility (due to cold or heat) and Tp at sensitive stages was established across sites and varieties. Those results showed that for irrigated rice, humid and moderately hot environments are more subject to heat stress sterility than very hot but dry environments, because panicle and canopy transpiration are favored by high VPD. Ultimately, RIDEV V.2 crop model (predicting spikelet sterility) was developed to integrate the previous results and Tp simulations were compared to another Tp model (IM2PACT) simulations, developed independently with a different approach in Japan. Those two models are robust and future collaborations will lead to complete model validations and maybe integration in a new modeling tool to answer the need in evaluating the impact of different climate change scenarios and the adaptation of crop response to those changes.In a short term, the results of this study will enable to 1) help breeders providing them new interest traits for thermal tolerance, and 2) define geographic zoning for high heat stress risk for irrigated rice, for present and future climate change scenarios. Complementary studies are needed to apply this approach to non irrigated system.

Les stérilités mâles cytoplasmiques (SMC) résultent d'une incompatibilité nucléo-cytoplasmique. Le cytoplasme (presque toujours la mitochondrie) peut porter un gène de stérilité mâle, et le noyau peut restaurer la fertilité pollinique ou non. Les mécanismes physiologiques conduisant à la mort pollinique restent largement incompris. Plusieurs hypothèses ont été proposées, parmi lesquelles une déficience en ATP. Une SMC gamétophytique a été découverte chez A. thaliana. Une phase ouverte de lecture codant possiblement un peptide de 117 acides aminés, appelée orf117Sha, a été identifiée comme facteur de stérilité candidat.Au cours de ma thèse, j'ai cherché à valider le rôle de l'orf117Sha, et à comprendre comment une anomalie mitochondriale pouvait induire cette SMC. Aucune différence n'a pu être détectée au niveau de l'ARNm de l'orf117Sha entre les lignées stérile et restaurée, mais sa protéine semble accumulée uniquement dans la lignée stérile. La phénocopie par transgénèse de la SMC a suggéré un effet délétère de l'ORF117SHA dans les gamétophytes mâle et femelle.La description cytologique de la SMC montre une mort pollinique progressive à partir du stade binucléé. Auparavant, les mitochondries du pollen gonflent puis éclatent, et le développement s'arrête. L’utilisation de senseurs génétiquement encodés mesurant la concentration en ATP (ATeam) et l'état redox du glutathion (roGFP2-Grx1) a permis la mesure de ces facteurs en microscopie confocale, dans des tissus végétatifs et dans le pollen. La production d'ATP ne semble pas affectée dans la lignée stérile, contredisant l'hypothèse de l'ATP. Le glutathion mitochondrial est suroxydé dans la lignée stérile, à la fois dans les tissus végétatifs étudiés et le pollen, qui serait liée à la SMC car annulée par la restauration génétique de fertilité.Avec cette étude, j'apporte des arguments en faveur de l'orf117Sha dans l'induction de la SMC Sha, et je décris les évènements préalables à l'avortement du grain de pollen. Mes résultats permettent de mieux comprendre les évènements physiologiques conduisant à la mort du pollen. / This work aims at better understand the events leading to pollen abortion in a recently discovered gametophytic cytoplasmic male sterility (CMS) in Arabidopsis thaliana. Although CMS have been widely used in hybrid seed production in many crops, the physiological mechanisms leading to pollen death by the mitochondrial sterilizing genes in the permissive (maintainer) nuclear backgrounds are poorly understood. Association genetics previously identified orf117Sha as a candidate mitochondrial CMS-associated gene.In a first part, I analyzed the expression of the orf117Sha gene in sterile plants and in fertile plants carrying nuclear genes restoring male fertility. I observed unusual features of its mRNA, but detected no difference at this level between sterile and restored plants. Oppositely, the ORF117SHA protein seems to be accumulated specifically in the sterile line, supporting its role in CMS. A phenocopy attempt by transgenesis suggested a possible link between a female and male gametophytic lethality and the ORF117SHA, even though few individuals could be analyzed.In a second part, I observed pollen development in sterile plants and fertile controls using different cytological approaches. My results show a progressive pollen death starting from the binucleate stage in the sterile. Prior to abortion, pollen mitochondria swell before rupture, and the development stops. I used confocal microscopy combined with genetically encoded sensors to explore specific physiological features in pollen and vegetative tissues of sterile plants. With ATeam, which allows the assessment of ATP content in the cytosol, I could challenge the generally accepted hypothesis of an ATP deficiency leading to pollen abortion in CMS. Indeed, the ATP production does not seem to be affected in the sterile line. With a mitochondria-addressed roGFP2-Grx1, I was able to assess the redox state of the glutathione pool in vegetative tissues and in the male gametophyte. I observed an overoxydation of the glutathione pool in mitochondria of the sterile line, in vegetative tissue investigated and in the pollen grain. This overoxydation seems to be linked to the CMS as it is annihilated by the presence of restorer genes.My results pave the way for further exploration of the links between the sterility protein, mitochondrial morphology changes, mitochondrial overoxydation, and pollen development arrest and death in the A. thaliana CMS.

The production of haploid sperm is a precondition for sexual reproduction of males. PRDM9 protein is a histone methyltransferase which localizes sites of meiotic recombination in many mammals. Mouse males of the C57BL/6J (B6) strain deficient for Prdm9 (Prdm9-/- ) are sterile, while Prdm9-/- males of PWD/Ph (PWD) strain have reduced sperm count. The comparison of the distribution of trimethylation of histone 3 on lysine 36 (H3K36me3) in genome of Prdm9-/- males of these two strains will help to determine the role of this epigenetic modification on meiotic recombination and fertility of Prdm9-/- males. The second part of this thesis is focused on transgenic males. Male offspring from the first generation of B6 female and PWD male crosses (B6PF1) have reduced fertility parameters due to incompatibility of Prdm9 alleles. The fertility parameters of B6PF1 hybrids carrying CHORI-34-289M8 or RP24-346I22 transgene are even lower. The candidate gene, which participates in the reduction of fertility of the transgenic B6PF1 hybrids, was determined as the proteasome subunit encoding gene Psmb1, because its relative transcription level best correlates with sperm count. The reason of lowered fertility thus might be a defect in proteasome assembly. The investigation of the fitness of transgenic animals is...

Speciation, the formation of new species, is an essential evolutionary process that causes species diversity on the Earth. At the beginning of this process is the separation of two populations by a reproductive barrier that prevents gene flow between these populations. One of the mechanisms, which enable reproductive isolation, is hybrid sterility (HS). It is a mechanism of postzygotic isolation that is described in a number of eukaryotes. The first discovered gene of hybrid sterility in vertebrates is the mice gene Hst1, later identified as gene Prdm9. By genetic and molecular analysis the locus on the X chromosome was determined, whose interaction with Prdm9 causes sterility or reduced fitness in male hybrids. This locus contains two genetic factors: Hstx1, causing an abnormal morphology of spermatozoa, and Hstx2, causing an arrest in spermatogenesis in pachytene spermatocytes and sterility. In my thesis I focus on the effect of deletion of a candidate hybrid sterility gene Fmr1nb on the X chromosome. The analysis of males B6N.Fmr1nbmut with deletion variants of the Fmr1nb gene showed that Fmr1nb is one of the factors influencing spermatogenesis. An increase in morphologic abnormalities in spermatozoa occurred in males with Fmr1nb gene deletion. This phenotype is identical with Hstx1. The effect...

L'acide ascorbique (AsA, vitamine C) est l'un des composés parmi les plus importants chez les eucaryotes. En raison de son potentiel antioxydant élevé, l'AsA représente un trait important de la qualité nutritionnelle des végétaux. Au-delà de sa valeur bénéfique pour la santé, une augmentation de la teneur en AsA des fruits bénéficierait probablement à la qualité post-récolte et à la résistance aux pathogènes. Pour mieux comprendre ces régulations chez les plantes et leurs impacts sur la qualité des fruits, une collection de tomates EMS hautement mutée (cv. Micro-Tom) a été criblée pour identifier des mutants dont les fruits sont enrichis en AsA. Cette stratégie de génétique directe associant le criblage à une approche de cartographie par séquençage devait permettre d’identifier de nouveaux gènes liés au caractère AsA+. L'un des mutants, noté P21H6, présentait un enrichissement en AsA de 2 à 4 fois supérieur à celui du WT, et fut le premier à être génétiquement caractérisé. Cette étude a permis de mettre en évidence une nouvelle classe de photorécepteurs impliqués dans la détection de la lumière bleue, appelée SlPLP, en tant que régulateur négatif de l'accumulation d'AsA dans la tomate. Le rôle de PLP dans le phénotype AsA+ du fruit a été confirmé par une stratégie de mutagenèse dirigée, avant d’entreprendre sa caractérisation fonctionnelle. Nous avons démontré que SlPLP interagit avec SlGGP (GDP-L-galactose phosphorylase), une enzyme clé de la voie du L-Galactose, sous contrôle de la lumière bleue et que cette interaction a lieu dans le cytoplasme et le noyau. Nos résultats renforcent le rôle central du GGP dans la biosynthèse de l'AsA et suggèrent un nouveau mécanisme de régulation par la lumière bleue de la fonction du GGP, en plus de son activité métabolique. Parallèlement, nous avons entrepris la caractérisation d’un autre mutant, le P17C5-3, qui présentait le plus fort taux d'AsA (jusqu'à 10 fois le WT). Outre le phénotype AsA+, le mutant P17C5 présentait de fortes altérations morphologiques, notamment l’absence de graines, rendant la mise en place de la stratégie de cartographie difficile. Grâce à un croisement avec la variété commerciale M82, la mutation causale pu être identifiée dans un ORF cis-régulateur en amont de GGP. Ce résultat confirme le rôle clé de GGP dans la voie L-Galactose. Des études préliminaires liées au phénotype parthénocarpique suggèrent un problème de stérilité mâle associé aux processus de développement du pollen. Enfin, dans l’étude de la qualité des fruits après la récolte, des expériences de stress froid effectuées avec les fruits P21H6 semblent démontrer que l’augmentation de la teneur en AsA améliore la durée de conservation et la capacité de maturation des fruits. Dans l'ensemble, nos résultats confirment la position clé de la protéine GGP dans la voie de biosynthèse de l'AsA, et fournissent des outils et du matériel végétal précieux pour décortiquer la régulation de l'AsA et son rôle physiologique dans la qualité des fruits et les caractères post-récolte. / Ascorbic acid (AsA, vitamin C) is one of the most important biochemical in living organisms. Due to its high antioxidant potential, AsA represents an important trait of nutritional quality in fruits and vegetables. In addition to its beneficial health value in fruit consumption, increasing fruit AsA content would likely affect postharvest quality and resistance to pathogens. Thus, understanding the regulation of AsA accumulation in order to improve crop species of agronomical interest is an important issue in plant breeding for many fleshy fruit species. To get a better understanding of the regulation of AsA level in plants and its impact on fruit quality, a highly mutagenized EMS tomato collection (cv. Micro-Tom) was screened for AsA+ fruit mutants. This forward genetic strategy combined with a mapping-by-sequencing approach, had allowed identifying new genes related to the AsA+ trait. One of the mutant line named P21H6, displayed an AsA-enrichment 2 to 4 fold that of the WT, and was the first to be genetically characterized. It allowed highlighting a new class of photoreceptor involved in blue light sensing named SlPLP as a negative regulator of AsA accumulation in tomato. We confirmed the role of the PLP in the fruit AsA+ phenotype using a directed mutagenesis strategy, undertaking its functional characterization. We demonstrate that PLP interacts with GGP (GDP-L-galactose phosphorylase), a key enzyme of the L-Galactose pathway, under blue light control and that this interaction takes place in the cytoplasm and the nucleus. Our results strengthen the central role of GGP in the AsA biosynthesis and suggest a new regulation mechanism by blue light of the GGP function in addition to its metabolic activity. Besides we started the characterization another mutant, the P17C5-3, which displayed the highest level of AsA (up to 10 times the WT). Beyond its AsA+ content, the P17C5 mutant showed strong morphological alterations including a seedless phenotype making the mapping difficult at first. Thanks to the crossing with the commercial M82 tomato cultivar, the causal mutation was identified in a cis-acting ORF, upstream of the GGP gene. This result confirmed the key role of GGP in the L-Galactose pathway. Preliminary studies related to the parthenocarpic phenotype suggest a problem of male sterility associated with pollen development processes. Finally, in the study of the post-harvest fruit quality, chilling stress experiments carried out with the P21H6 fruits seem to demonstrate that increasing AsA content improve the fruit shelf life and its maturation capacity. Taken as a whole, our results confirmed the key position of the GGP protein in the AsA biosynthesis pathway and they provided precious tools and plant material for deciphering the regulation of AsA and its physiological role in fruit quality and post-harvest traits.