L'aggravation actuelle du risque lié au paludisme résulte du développement du phénomène de résistance de souches de Plasmodium falciparum aux molécules antipaludiques. Une telle situation et l’absence de vaccin efficace nécessitent le développement de nouvelles stratégies antiparasitaires. Jusqu’à présent, les mécanismes moléculaires qui contrôlent le cycle parasitaire sont méconnus. Chez la plupart des eucaryotes, les protéine kinases sont impliquées dans des fonctions cellulaires essentielleset constituent une cible privilégiée pour la conception de nouveaux médicaments. Dans cecadre, nous nous sommes intéressés à la voie de transduction de l’AMP cyclique et en particulier à la sous-unité catalytique de la protéine kinase AMPc dépendante (PfPKAc)dont le rôle essentiel reste mal défini chez P. falciparum. Deux approches complémentaires ont été choisies pour étudier cette kinase :1) au niveau biochimique par le clonage, l’expression, la purification et la caractérisation enzymatique de la PfPKAc. L’objectif était d’obtenir une enzyme active in vitro de façon à pourvoir mesurer les constantes enzymatiques de la PfPKAc et conduire les premiers essais d’inhibitions.2) au niveau cellulaire en analysant les conséquences de l’inhibition par des ARN interférents spécifiques des transcrits de la PfPKAc. Le développement parasitaire mais également le transcriptome global ont été étudiés de manière à préciser les voies métaboliques liées à cette kinase plasmodiale.L’ensemble de ces études précise la compréhension de la voie de transduction de l’AMP cyclique et de la PfPKA qui pourrait conduire au développement de nouvelles voies thérapeutiques. / Nowadays, the increase of risks associated with malaria results from the development of resistance of Plasmodium falciparum strains to antimalarial drugs. This situation and the lack of an effective vaccine require the development of new antimalarial strategies. Untilnow, molecular mechanisms controlling the life cycle of malaria parasites, are still poorly understood. In most eukaryotes, protein kinases are implicated in essential cellular functions and represent attractive targets for the development of new drugs. In this context, we focused on the signaling pathway implicating cAMP and particularly the catalytic subunit of cAMP-dependent protein kinase (PfPKAc), whose function is still unclear in P. falciparum. Two complementary strategies were chosen to study this kinase:1) at the biochemical level by the cloning, expression, purification and enzymatic characterization of the PfPKAc. The objective was to obtain an in vitro active PfPKAc to evaluate the kinetic constants of PfPKAc and to conduct the first inhibition studies.2) at the cellular level by studying the consequences of PfPKAc transcripts inhibition byspecific interfering RNAs. The parasite growth but also the overall transcriptome werestudied to specify the metabolic pathways associated with this plasmodial protein kinase.All of these studies improve the understanding of cAMP transduction pathway and PfPKA,which could allow the development of new therapeutic approaches.

Le blé tendre, Triticum aestivum, est une des céréales les plus cultivées au monde et est d’une importance considérable pour l’alimentation humaine, fournissant environ un cinquième des calories consommées par l’Homme. Le rendement en grain chez les céréales dépend majoritairement du nombre et de la taille des grains. Chez le riz (Oryza sativa), le gène GW2 a été isolé dans un locus à effet quantitatif majeur pour la taille et le poids du grain. Ce gène code pour une enzyme E3 ligase de type RING, qui régule négativement la taille et le poids du grain de riz. L’homologue de GW2 chez le blé tendre, le gène TaGW2, est exprimé par trois copies TaGW2-A,TaGW2-B et TaGW2-D, portées par chacun des génomes homéologues A, B et D. Les trois copies présentent des profils d’expression distincts au cours du développement du grain. TaGW2-A a été cartographié dans une région de QTLs pour le rendement, sur le chromosome 6AS ; et du polymorphisme dans sa séquence promotrice et intronique a été retrouvé associé au poids de 1000-grains dans une core collection mondiale de blé tendre. Afin de rechercher la fonction de TaGW2, l’extinction stable des trois copies TaGW2 a été entreprise par ARN interférence. De manière surprenante, les plantes transgéniques montrent des réductions significatives des dimensions et du poids du grain de blé (- 22,5 et - 30% du volume et de la masse du grain, respectivement), ainsi que du nombre de cellules de l’albumen (- 25%), comparé aux plantes témoins dans nos conditions ; suggérant que TaGW2 est un régulateur positif de la taille finale du grain chez le blé tendre. La protéine TaGW2-A a été caractérisée aux niveaux moléculaire et biochimique : elle est une E3 ubiquitine ligase fonctionnelle in vitro, et s’accumule dans la cellule au niveau du nucléole, du nucléoplasme et du cytoplasme. Sa fonction E3 ligase semble notamment influencer sa localisation subcellulaire. Afin de déterminer la ou les voie(s) de signalisation dans la(es)quelle(s) intervient TaGW2, une banque ADNc de grains de blé a été construite et criblée par double-hybride avec 320 acides aminés de la protéine TaGW2-A. Les premiers interacteurs potentiels identifiés suggèrent d’une part un rôle de TaGW2 dans la régulation de la division cellulaire, et d’autre part une fonction E3 Nedd8 ligase, en plus de son activité E3 ligase. / Wheat, Triticum aestivum, is one of the world’s major cereal crops and is of considerable importance to human nutrition, supplying one-fifth of the calories consumed by humans. For important food crops such as wheat, rice and maize, grain yield mainly depends on grain number and size. In rice (Oryza sativa), GW2 was isolated from a major quantitative trait locus for grain size and weight, and encodes an E3 RING ligase that negatively regulates these yield components. Wheat has TaGW2 homologs in A, B and D genomes; and copies show distinct expression pattern during whole grain development in wheat. TaGW2-A was mapped in a genomic region on 6AS, encompassing previous reported QTLs for yield; and polymorphisms in TaGW2-A (promoter and intron 7) were associated with thousand-grain weight, in a worldwide wheat core collection. To investigate TaGW2 function, RNA interference was used to down-regulate TaGW2 transcripts levels. Surprisingly, transgenic wheat lines significantly showed decreased grain weight and size-related dimensions, and endosperm cell number compared to controls. The present study thus suggests that TaGW2 is a positive regulator of the final grain size in wheat, conversely to GW2 in rice. Biochemical and molecular analyses of the protein TaGW2-A revealed that 1) TaGW2-A is a functional E3 ubiquitine ligase in vitro, 2) TaGW2-A accumulates in the nucleolus, the nucleoplasm, and the cytosol, 3) E3 ubiquitine ligase activity seems to impact TaGW2-A subcellular localization. To investigate the TaGW2 signalling pathway(s), cDNA library from whole wheat grains was built and screened with the bait protein TaGW2(1-320). Preliminary results from the interactomic study suggest that TaGW2 may regulate cell division. Moreover, TaGW2 may also function as an E3 Nedd8 ligase, besides its E3 ubiquitin ligase function.

Mgr. Daniela Fornuskova PhD thesis Biochemical and molecular studies of cytochrome c oxidase and ATP synthase deficiencies ABSTRACT The mammalian organism fully depends on the oxidative phosphorylation system (OXPHOS) as the major energy (ATP) producer of the cell. Disturbances of OXPHOS may be caused by mutations in either mitochondrial DNA (mtDNA) or nuclear DNA (nDNA). One part of the thesis is focused on the role of early and late assembled nuclear-encoded structural subunits of cytochrome c oxidase (CcO) as well as Oxa1l, the human homologue of the yeast mitochondrial Oxa1 translocase, in the biogenesis and function of the human CcO complex using stable RNA interference of COX4, COX5A, COX6A1 and OXA1L, as well as expression of epitope-tagged Cox6a, Cox7a and Cox7b, in HEK (human embryonic kidney)- 293 cells. Our results indicate that, whereas nuclear- encoded CcO subunits Cox4 and Cox5a are required for the assembly of the functional CcO complex, the Cox6a subunit is required for the overall stability of the holoenzyme. In OXA1L knockdown HEK-293 cells, intriguingly, CcO activity and holoenzyme content were unaffected, although the inactivation of OXA1 in yeast was shown to cause complete absence of CcO activity. In addition, we compared OXPHOS protein deficiency patterns in mitochondria from skeletal...

Le cancer du col de l’utérus est le troisième cancer le plus fréquent chez la femme, dont l’agent étiologique majeur est l’infection par les papillomavirus humain (notamment HPV-16 et 18), qui sont de petits virus infectant les épithéliums muqueux et cutanés, et pouvant induire la formation de tumeurs. L’inducteur majeur du processus oncogène est le processus d’intégration des régions codantes pour les oncoprotéines E6 et E7, au sein de la cellule hôte suite à l’infection. Elles interférent avec le cycle cellulaire et induisent notamment l’immortalisation, voire la transformation des cellules. Les fonctions les plus connue de ces deux oncoprotéines sont la dégradation des suppresseurs de tumeur p53 et pRb, respectivement. Mon travail de thèse à consisté en la mise au point des vecteurs adénoviraux exprimant des miARN dirigés contre l’oncoprotéine E6. Exprimés in vitro ils induisent l’induction de la mort cellulaire par apoptose des cellules tumorales traitées, via l’activation de la voie de caspases, et in vivo permettent le ralentissement de la croissance de tumeurs xénogreffées à des souris Nude. De plus, la stratégie thérapeutique adénovirale a montré ses extensions possibles sur d’autres types de cancers HPV-positifs, mais également via l’expression de différentes moléculaires thérapeutiques, visant à empêcher l’interaction des oncoprotéines telles qu’E6 avec leurs partenaires cellulaires et ainsi les empêcher d’exercer les activités biologiques impliquées dans le développement de cancers. Pour finir, les adénovirus peuvent également être vu comme des outils d’extinction fonctionnels d’E6 et permettant d’étudier les répercutions sur d’autres processus cellulaires. / Cervical cancer is the third most common female cancer. Infection by human papillomavirus (mainly HPV-16 and 18), with tropisms for mucosal or cutaneous squamous surfaces, is the major etiological agent implicated in cancer and tumor development. After infection, the oncogenic process is triggered by integration of oncoproteins E6 and E7 coding regions into the host cell genome. After integration, these oncoproteins interfere with the cell cycle and induce immortalization and cellular transformation of normal cells. The best known function of these two oncoproteins is the degradation of tumors suppressors p53 and pRb respectively. My thesis project consisted in the development of adenoviral vectors expressing miRNA directed against E6 oncoprotein. Their in vitro expression resulted in cellular death by apoptosis of the treated tumor cells, and allowed reduction of tumor growth in vivo in nude mice xenografts. In addition, the adenoviral therapeutical strategy showed its possible extensions on other types of HPV-positive cancers, but also through the possible expression of different therapeutic molecules aimed at preventing the interaction of viral oncoproteins, such as E6, with their cellular partners. These abolished interactions prevent oncoproteins from exercising their biological activities implicated in the development of cancers. In conclusion, we can say that adenoviruses can also be seen as functional tools suppressing E6 and enabling to highlight the repercussions of its suppression on other cellular processes.

O adenocarcinoma pancreático ductal representa a quarta causa de morte por câncer, visto que as taxas de incidência são praticamente idênticas às taxas de mortalidade, o que justifica a natureza altamente agressiva do tumor. Em uma análise preliminar realizada por nosso grupo, avaliou-se a expressão do gene homeobox HOXB7 nas linhagens celulares MIA PaCa-2, BxPC-3 e Capan-1, bem como em tecidos pancreáticos normais, detectando-se o aumento significativo da expressão nas células derivadas de adenocarcinoma pancreático. Alterações na expressão de HOXB7 foram relatadas na formação e progressão de outros cânceres. Nessas condições, este estudo visou não somente avaliar a expressão deste gene em uma série de 29 adenocarcinomas pancreáticos ductais, 6 tecidos metastáticos e 24 tecidos peritumorais, comparando-os aos tecidos normais, mas também averiguar o efeito de sua inibição sobre o perfil de expressão das células citadas. A análise da expressão gênica demonstrou a hiperregulação do transcrito do gene HOXB7 nos tecidos tumorais, corroborando os resultados observados nas linhagens celulares MIA PaCa-2, BxPC-3 e Capan-1. A inibição realizada com RNA de interferência promoveu a modulação de diferentes processos biológicos nas três linhagens celulares pesquisadas, bem como a indução de apoptose e diminuição da proliferação das células MIA PaCa-2. Nesse contexto, o homeobox neste estudo investigado representa mais um componente associado à ampla rede de moléculas envolvidas na caracterização do câncer pancreático e um promissor alvo para futuras terapias biológicas / The pancreatic ductal adenocarcinoma is the fourth leading cause of cancer death, whereas the incidence rates are practically identical to mortality rates, which explains the highly aggressive tumor. In a preliminary analysis performed by our group, we evaluated the expression of the homeobox gene HOXB7 in cell lineages MIA PaCa-2, BxPC-3 and Capan-1, as well as in normal pancreatic tissue, detecting a significant increase in expression in cells derived from pancreatic adenocarcinoma. Changes in expression of HOXB7 were reported in the formation and progression of other cancers. Under these conditions, this study aimed to not only evaluate the expression of this gene in a series of 29 pancreatic ductal adenocarcinomas, 6 metastatic tissues and 24 peritumoral tissues, comparing them to normal tissues, but also examined the effect of its inhibition on the expression profile of the cells mentioned. The analysis of gene expression showed the hyper-regulation of HOXB7 gene transcript in the tumor tissues, confirming the results observed in cell lineages MIA PaCa-2, BxPC-3 and Capan-1. The inhibition performed with RNA interference promoted the modulation of different biological processes in all three cell lines investigated, as well as the induction of apoptosis and decreased in proliferation of the MIA PaCa-2 cells. In this context, the homeobox investigated in this study represents another component associated with the extensive network of molecules involved in the characterization of pancreatic cancer and a promising target for future biologic therapies

Orientador: Iscia Lopes-Cendes / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-13T04:41:41Z (GMT). No. of bitstreams: 1 Conte_FabioFrangiotti_D.pdf: 13814383 bytes, checksum: 9a4218c46168df9b7544dbd102ee9756 (MD5) Previous issue date: 2009 / Resumo: A epilepsia é uma condição bastante freqüente que atinge aproximadamente 1,5% da população geral, sendo mundialmente considerada um problema de saúde pública. O termo epilepsia engloba um grupo de distúrbios neurológicos crônicos com diferentes etiologias, manifestações e prognósticos, mas que possuem como característica comum as crises convulsivas recorrentes. A Epilepsia Mioclônica Juvenil (EMJ) é caracterizada por abalos mioclônicos principalmente ao despertar. A EMJ tem sido uma das formas de epilepsia mais amplamente estudadas do ponto de vista molecular. Recentemente, um dos genes causadores da EMJ foi clonado. Este gene, chamado de EFHC1, codifica uma proteína que possui 640 aminoácidos e que possui três domínios estruturais DM10, de função desconhecida, e um motivo de ligação a cálcio, chamado de EF-hand. A proteína EFHC1 associa-se a microtúbulos e, dessa forma, participa ativamente do processo de divisão celular. Além disso, esta proteína induz apoptose em neurônios através da sua associação com um canal de cálcio voltagem-dependente (Cav2.3). Foram identificadas cinco mutações no gene EFHC1 que co-segregam com o quadro epiléptico em pacientes acometidos por EMJ. As proteínas mutadas codificadas por estas variantes têm a capacidade pró-apoptótica reduzida. Os genes ortólogos de camundongo e rato, chamados de Efhc1, também foram isolados. O gene murino codifica uma proteína de aproximadamente 75KDa, homóloga à proteína Rib72 de Chlamydomonas reinhardtii. A proteína Efhc1 é abundante em tecidos e órgãos que possuem flagelos ou cílios móveis, como, por exemplo, os testículos, os ovidutos e, no sistema nervoso central (SNC), as células ependimárias. No epêndima, a proteína Efhc1 é essencial para a manutenção da freqüência de batimento ciliar destas células. Os principais objetivos desta tese foram a determinação do perfil de expressão do gene Efhc1 e a avaliação da viabilidade de estudos funcionais pela modulação de sua expressão no cérebro de roedores em diferentes estágios de desenvolvimento. Os experimentos de reação em cadeia da polimerase (PCR) em tempo real revelaram que não há diferença na expressão do transcrito do gene Efhc1 entre os hemisférios cerebrais nas duas espécies. Os ensaios de Western blot corroboraram este achado. Além disso, os maiores níveis do transcrito destes genes são observados nos estágios intra-uterinos nos camundongos e nos animais adultos em ratos. Em comum, há um decréscimo progressivo na expressão dos genes a partir de neonatos de 1 dia de vida (P1) até P14. Os estudos de hibridização in situ mostraram que o transcrito dos genes Efhc1 destas espécies é expresso nas células ependimárias, as quais revestem as paredes dos ventrículos cerebrais. Estes resultados sugerem que a expressão do gene Efhc1 é mais importante durante as fases iniciais do desenvolvimento do cérebro e que, neste estágio, a proteína Efhc1 pode estar envolvida no surgimento dos mecanismos epileptogênicos subjacentes a EMJ. A técnica de interferência por RNA (RNAi) promove o silenciamento gênico potente e específico e foi utilizada neste projeto com o intuito de estudar a função do gene Efhc1 em células de mamíferos em cultura e no cérebro de camundongos em desenvolvimento. Esta abordagem tem sido amplamente utilizada para esta finalidade. Tanto para os experimentos com cultura celular quanto para os experimentos in vivo, a confirmação do silenciamento gênico ocorreu via Real Time PCR e Western blot. Além disso, foram utilizados controles negativos (injeção apenas com tampão e siRNA irrelevantes). Inicialmente, foram desenhadas e sintetizadas duas moléculas de siRNA, as efetoras da RNAi, que promovem um silenciamento gênico temporário, e uma molécula de shRNA (short hairpin RNA), cujo efeito é duradouro. Nos experimentos com cultura de células, foram utilizados diferentes tipos celulares, desde cardiomiócitos de rato até células de camundongos derivadas de neuroblastoma (Neuro2A). Já para o silenciamento do gene no cérebro de camundongos em desenvolvimento, foram utilizadas diferentes metodologias de inoculação da molécula, como, por exemplo, cirurgia intra-uterina, transfecção hidrodinâmica, injeção na veia jugular e associação do siRNA com um peptídeo derivado de uma glicoproteína do vírus da raiva. Como resultado, obteve-se silenciamento duradouro e consistente do gene Efhc1 em cultura de células Neuro2A. A maior porcentagem de silenciamento gênico (60%) foi obtida após 48h de incubação do siRNA com as células e o gene permaneceu silenciado por até 6 dias. Além disso, o silenciamento do gene Efhc1 no Sistema Nervoso Central de roedores (redução da expressão em até 45%) foi alcançado pela complexação do siRNA com um peptídeo derivado do vírus da raiva, o RVG-9R. Espera-se que os resultados deste estudo sejam capazes de fortalecer a associação do gene EFHC1 e o fenótipo de EMJ, além de fornecer maiores subsídios para identificar os possíveis mecanismos biológicos envolvidos na fisiopatologia da EMJ, os quais permanecem ainda muito controversos. / Abstract: Epilepsy is a frequent condition that affects around 1.5% of general population and is considered worldwide as a public health problem. The term epilepsy refers to a group of chronic neurological disorders with different etiologies and prognostics. However, a common characteristic of all epilepsies is the recurrence of seizures. Juvenile myoclonic epilepsy (JME), one of the most common forms of epilepsy, is characterized by myoclonic seizures mainly at awakening. JME has been intensively studied at the molecular level. Recently, one of the putative causative genes for JME was cloned. This gene, called EFHC1, encodes a protein with 640 amino acids that has three DM10 domains, with unknown function, and a calcium binding motif, called Ef-Hand. EFHC1 protein associates with microtubules and, therefore, it actively participates in the cellular division process. In addition, it has been demonstrated that this protein induces apoptosis in cultured neurons through the association with an R-type voltage-dependent calcium channel (Cav2.3).To date, five different EFHC1 missense mutations identified in patients with JME were shown to decrease this proapoptotic function in cell models. The ortholog genes in mouse and rat, both named Efhc1, were also isolated. The murine gene encodes a protein with around 75KDa, homolog to Chlamydomonas reinhardtii Rib72 protein. Efhc1 protein presents its highest expression levels in tissues and organs that have mobile cilia and flagella, like testis, oviduct and, in the central nervous system, the ependymal cells. The aim of this study was to determine the distribution and expression profile of Efhc1 genes and evaluate the viability of functional studies by the modulation of the its expression during the development of the brain of mice and rats. Real time polymerase chain reaction (Real Time PCR) revealed that there is no difference in the expression of Efhc1 transcript between right and left hemispheres in both species. Western blot experiments corroborated this finding. In addition, the highest levels of Efhc1 mRNA were found at intra-uterine stages in mouse and in adulthood in rat. In common, there was a progressive decrease in Efhc1 expression from 1-day-old neonates to 14-days-old animals in both species. In situ hybridization studies showed that rat and mouse Efhc1 mRNAs are expressed in ependymal cells of ventricle walls. Our findings suggest that Efhc1 expression is more important during initial phases of brain development and that at this stage it could be involved in key developmental mechanisms underlying JME. The technique of RNA interference (RNAi) promotes a potent and specific gene silence and it was employed in this project to study the function of Efhc1 gene in cultured mammal cells and in the brain of mice in different developmental stages. This approach has been widely used to achieve this aim. Both for cultured cells assays as for in vivo experiments, the percentage of gene silence was evaluated with Real Time PCR and Western blot. In addition, negative controls (injection only with buffer and the use of an irrelevant siRNA) were used in the experiments. Initially, we used two siRNAs, the effectors of RNAi. The siRNA molecules promote a temporary gene silence, whereas the short hairpin RNA (shRNA), another type of molecule, promotes long-term gene silence. In the experiments with mammal cells in culture, we used different cellular types, from rat cardiomyocytes to mouse neuroblastoma cells. For the in vivo experiments, different methodologies were used, such as intra-uterine surgery, hydrodynamic transfection, and association of the siRNA with a peptide derived from a rabies virus glycoprotein. A long-term Efhc1 gene silencing was obtained in Neuro2A cells. The greatest silencing percentage (60%) was observed after 48h of incubation with the siRNA and the gene remained silenced for up to 6 days. Besides, Efhc1 gene silencing in rodent Central Nervous System (decrease in gene expression of 45%) was achieved by the inoculation of the siRNA-RVG-9R complex. We believe that our results point to an association between putative EFHC1 gene function during brain development and the physiopathology of JME. / Doutorado / Genetica Animal e Evolução / Doutor em Genetica e Biologia Molecular

Embora desfrute de inegável importância econômica, os citros estão sujeitos a muitos problemas sanitários sendo alguns, limitantes para o cultivo como é o caso das doenças causadas por vírus. A morte súbita dos citros é uma doença relacionada à combinação copa/ porta-enxerto e manifesta sintomas na região da enxertia sobre porta-enxertos intolerantes. Embora sua etiologia não tenha sido determinada, há indicações que a causa da MSC esteja relacionada a uma estirpe do vírus da tristeza dos citros (CTV), a um vírus do gênero Marafivirus, ou a uma associação entre eles. Uma vez que a transformação genética têm sido considerada como uma ferramenta auxiliar a programas de melhoramento de citros, o objetivo deste trabalho foi obter plantas transgênicas de limão \'Cravo\' e laranja \'Valência\' contendo o gene da replicase do Marafivirus e estudar a regeneração e obtenção de plantas in vitro de laranja azeda, via organogênese, visando futuros trabalhos de transformação genética. Experimentos para indução da organogênese in vitro foram realizados avaliando-se citocininas (BAP, TDZ e CIN), em diferentes concentrações, isoladamente ou em combinação com ANA, condições de luminosidade (fotoperíodo de 16 h e escuro por 30 dias), meios de cultivo e explantes (provenientes de plantas germinadas in vitro e de plantas mantidas em estufa). Além disso, avaliou-se o enraizamento dos brotos regenerados. Para a transformação genética, explantes de limão \'Cravo\' e laranja \'Valência\' foram inoculados e co-cultivados com a estirpe EHA 105 de Agrobacterium tumefaciens contendo o gene da replicase do Marafivirus (em seqüência sense e antisense interligadas por um íntron). A construção gênica foi elaborada a partir do plasmídeo pCAMBIA 2201, dirigidas pelo promotor 35S e terminador NOS, contendo ainda o gene de seleção nptII. A transformação foi confirmada por análises de PCR e \'Southern blot\'. A transcrição do gene foi avaliada por RT-PCR e \'northern blot\'. A adição de BAP, combinada ou não com ANA, e em combinações com CIN ao meio de cultivo, assegurou maior formação de gemas adventícias em segmentos de epicótilo de laranja azeda. Entretanto, TDZ não se mostrou favorável a essa resposta, que também é afetada pela ausência de luz. Os explantes provenientes do cultivo in vitro mostraram-se mais favoráveis à resposta organogênica. O enraizamento das brotações de laranja azeda regeneradas foi obtido no meio MT com metade da concentração de sais, sem ou com auxinas. Foi possível obter plantas transgênicas de limão \'Cravo\' e de laranja \'Valência\' contendo o gene da replicase do Marafivirus utilizando-se segmentos internodais como explantes. A análise de \'Southern blot\' confirmou a integração de um a quatro eventos de inserção do transgene no genoma das plantas. A transcrição do gene da replicase do Marafivirus e do gene nptII foi observada por RT-PCR. / In spite of great economic importance, the citrus industry is affected by many phytopathological problems some, limiting its cultivation such as virus-caused diseases. The citrus sudden death disease is related to scion/rootstock combinations and manifests symptoms in the grafting area of intolerant rootstocks. Although its etiology has not been determined, there are indications that the cause of MSC might be related to a strain of the Citrus tristeza virus (CTV), to a virus of the Marafivirus group, or to an association of both viruses. Since the genetic transformation has been considered as an auxiliary tool to programs of citrus improvement, the objectives of this work were to obtain transgenic plants of the Rangpur lime and Valencia sweet orange containing the Marafivirus replicase gene and study the in vitro regeneration of sour orange plants through organogenesis, aiming for future work in genetic transformation. Experiments for induction of in vitro organogenesis were carried out evaluating citocinins (BAP, TDZ and KIN), in different concentrations, separately or in combination with NAA, lighting conditions (photoperiod of 16 hours and darkness for 30 days), cultivation media and explants (coming from in vitro germinated plants and from green house cultivated plants). Besides this, rooting of the regenerated shoots was evaluated. For the genetic transformation, Rangpur lime and Valencia sweet orange explants were inoculated and co-cultivated with the EHA-105 Agrobacterium tumefaciens strain containing the Marafivirus replicase gene (in sense and antisense sequence linked by an intron). The genetic construct used derived from the pCAMBIA 2201 plasmid, driven by the 35S promoter and NOS terminator, containing the selection nptII gene. The genetic transformation was confirmed by PCR and Southern blot analysis. The gene transcription was evaluated by RT-PCR and northern blot. The addition of BAP to the culture medium, combined or not with NAA, and in combinations with KIN, assured a greater formation of adventitious buds in sour orange epicotyl segments. However, TDZ was not favorable to this response, that is also affected by the absence of light. Explants coming from in vitro cultivation were more favorable to the organogenic response. Rooting of sour orange regenerated shoots was obtained in MT medium with half the salt concentration, with or without auxin. It was possible to obtain transgenic Rangpur lime and Valencia sweet orange plants containing the Marafivirus replicase gene using internodal segments as explants. The Southern blot analysis confirmed the integration of one to four copies of the transgene in the plant genome. The transcription of the Marafivirus replicase gene and the nptII gene was observed by RT-PCR.

O uso da técnica de RNAi vem sendo avaliada em diversos insetos-pragas pois, é uma estratégia inovadora que pode ser integrada no manejo de importantes pragas agrícolas. Os insetos da Ordem Lepidoptera são reconhecidos por apresentarem recalcitrância à técnica de silenciamento utilizando dsRNA. Assim, ajustes devem ser feitos aos métodos de entrega de dsRNA para que haja estabilidade da molécula até atingir o mRNA alvo de silenciamento no inseto. O silenciamento gênico por RNAi possui potencial de uso para o controle da \"traça-do-tomateiro\" Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), uma das principais pragas do tomateiro no mundo. O objetivo do trabalho foi selecionar e avaliar o silenciamento de genes de T. absoluta, utilizando o método de entrega de dsRNA via bactéria E. coli HT115 (DE3), disponibilizada em dieta artificial. Também, objetivando a aplicabilidade da utilização de bactérias que se desenvolvam no mesmo hábitat de insetos-pragas, estudou-se a colonização das bactérias endofíticas Pantoea agglomerans linhagem 33.1, Burkholderia sp. linhagem SCMS54 e Burkholderia ambifaria linhagem RZ2MS16 em plantas de tomateiro e lagartas de T. absoluta, para posterior transformação e tentativa de utilização como estratégia de entrega de dsRNA para silenciamento de genes alvos de T. absoluta. Foram avaliados, por meio da metodologia de dieta artificial, oito genes de T. absoluta: juvenile hormone inducible protein - JHP; juvenile hormone epoxide hydrolase protein - JHEH; ecdysteroid 25-hydroxylase - PHM; chitin synthase A - CHI; glutathione S-transferase epsilon 2 - GST; carboxylesterase - COE; alkaline phosphatase - AP e; arginine kinase - AK. Por meio de avaliação dos parâmetros biológicos (mortalidade larval; duração da fase larval e peso de pupas) e expressão gênica em cinco períodos de alimentação, comprovou-se a eficiência da metodologia na avaliação do silenciamento gênico por RNAi, sendo possível realizar screening de grande quantidade de genes e avaliar os efeitos do silenciamento gênico no desenvolvimento de T. absoluta. Os genes AK, CHI e JHP apresentaram resultados positivos quanto ao silenciamento gênico e mortalidade larval, sendo promissores para uso de silenciamento por RNAi como estratégia de controle de T. absoluta. Pantoea agglomerans apresentou os melhores resultados de colonização de plantas de tomateiro \"Micro-Tom\" e lagartas de T. absoluta, além de estarem presentes em tecidos preferencialmente utilizados na alimentação das lagartas. Porém, lagartas não apresentaram diferenças na mortalidade larval ao se alimentarem de plantas de tomateiro \"Micro-Tom\" inoculadas com bactérias de P. agglomerans transformadas. / The use of RNAi technique has been evaluated in several insect pests because it is an innovative strategy that can be integrated in the management of important agricultural pests. Insects of the Order Lepidoptera are recognized to present recalcitrance to gene silencing using dsRNA. Thus, adjustments should be done to dsRNA delivery methods to have molecule stability until it reaches the mRNA target for silencing in the insect. Gene silencing by RNAi has potential use to control the tomato leafminer Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), one of the main insect pests of tomato crop worldwide. The objective of this work was to select and evaluate the silencing of T. absoluta genes using dsRNA delivery method via E. coli HT115 (DE3) bacterium, offered in artificial diet. Also, aiming the applicability of the use of bacteria growing in the same habitat of insect pests, we evaluate the colonization of the endophytic bacteria Pantoea agglomerans strain 33.1, Burkholderia sp. strain SCMS54 and Burkholderia ambifaria strain RZ2MS16 in tomato plants and T. absoluta larvae for further transformation and potential use as dsRNA delivery strategy for silencing target genes of T. absoluta. We evaluated eight genes of T. absoluta: juvenile hormone inducible protein - JHP; juvenile hormone epoxide hydrolase protein - JHEH; ecdysteroid 25-hydroxylase - PHM; chitin synthase A - CHI; glutathione S-transferase epsilon 2 - GST; carboxylesterase - COE; alkaline phosphatase - AP and; arginine kinase - AK. Evaluating biological parameters (larval mortality, larval stage duration and pupal weight) and gene expression in five feeding periods, we proved the efficiency of the methodology in the evaluation of gene silencing by RNAi, and evaluated the effects of gene silencing on the development of T. absoluta. The genes AK, CHI and JHP presented positive results regarding gene silencing and larval mortality, being promising to use RNAi silencing as a strategy to control T. absoluta. Pantoea agglomerans showed good results colonizing \"Micro-Tom\" tomato plants and T. absoluta larvae, besides being present in tissues preferentially used by larvae for feeding. However, larvae did not show differences in larval mortality when feeding on tomato plants inoculated with transformed P. agglomerans.

Les moustiques anophèles sont les vecteurs du parasite Plasmodium l’agent du paludisme. Le parasite subit des pertes massives pendant son cycle de développement chez l’anophèle, ce qui suggère que les moustiques sont capables de développer une réaction immunitaire efficace contre le parasite. La connaissance de l’immunité et de la résistance des moustiques au genre Plasmodium provient principalement de systèmes de laboratoire qui utilisent des espèces de parasites de rongeurs ou d’oiseaux comme modèles du paludisme humain. Les observations présentées dans cette thèse suggèrent que certains gènes comme Tep1 et LRIM1 sont des médiateurs de réponses antiparsitiques contre différents Plasmodiums dans différents vecteurs. Cependant, le degré d'efficacité avec laquelle un moustique est capable de réduire le nombre de parasites peut être variable surtout entre combinaison de souche de moustique et de souche de parasite différentes, selon que la paire soit hautement compatible ou non.<p><p><p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

MicroRNAs are noncoding RNAs inducing sequence-specific posttranscriptional inhibition of gene expression and represent the major class of small endogenous RNAs in mammalian cells. Over 2,500 of human microRNAs potentially regulating more than 60% of human protein-coding genes have been identified. MicroRNAs participate in the majority of cellular processes, and their expression changes in various diseases, including cancer. Currently, there is no efficient small chemical compound available for the modulation of microRNA pathway activity. At the same time, small chemical compounds represent excellent tools for research of processes involving RNA silencing pathways, for biotechnological applications, and would have a considerable therapeutic potential. The presented work represents a part of a broader project, whose ultimate goal is: (i) to find a set of small molecules allowing for stimulation or inhibition of RNA silencing and (ii) to identify crosstalks between RNA silencing and other cellular pathways. This thesis summarizes results from the first two phases of the project, the development of high-throughput screening assays and the high- throughput screening (HTS) of available libraries of small compounds. To monitor the microRNA pathway activity, we developed and optimized one biochemical...