Tierärztl. Hochsch., Diss., 2003--Hannover.

Made available in DSpace on 2014-06-11T19:32:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-25Bitstream added on 2014-06-13T19:43:43Z : No. of bitstreams: 1 federicirodriguez_mt_dr_jabo.pdf: 2411830 bytes, checksum: 75b14273eb9f16da6c18c46ba363a68d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Foi construído um microarranjo com as 2600 ORFs identificadas no projeto de sequenciamento da bactéria Xylella fastidiosa estirpe 9a5c, e utilizado para analisar diferenças na expressão gênica global da bactéria dentro de uma laranja doce suscetível (Pera) e uma tolerante (cultivar Navelina ISA 315). Foram achados mais genes diferencialmente expressos envolvidos na degradação, reguladores, componentes de membrana, adesinas tipo fímbrias, transportadores, elementos genéticos móveis e genes de patogenicidade na variedade sintomática. Assim, na cultivar Navelina ISA 315, foram diferencialmente expressos mais genes relacionados com a resposta ao estresse, seja detoxificação de espécies reativas do oxigênio ou proteínas chaperonas, assim como uma adesina do tipo hemaglutinina. Isso sugere diferenças na agregação celular e composição do biofilme assim como um maior estresse da bactéria na cultivar tolerante, provocado pelas próprias defesas da planta ou por microrganismos endofíticos que estão competindo com a X. fastidiosa. A técnica de microarranjos foi validada pela RT-qPCR, e apresentou-se como uma ferramenta poderosa na análise das mudanças na expressão gênica da bactéria X. fastidiosa em plantas de laranja doce in vivo, apresentando uma visão mais real da natureza do que os sistemas in vitro, que não a conseguem imitar completamente. Foram levantadas neste trabalho algumas hipóteses sobre os mecanismos de patogenicidade mas no entanto, mais pesquisas ainda são necessárias para lograr melhor compreensão dos mecanismos de patogenicidade e das interações patógeno-hospedeiro / A DNA microarray was constructed containing 2600 ORFs identified by the Genome sequencing project of Xylella fastidiosa 9a5c strain, and used to check global gene expression differences in the bacteria within a susceptible and a tolerant sweet orange plant, the variety Pera and the cultivar Navelina ISA 315, respectively. More genes related to degradation, regulation, membrane components, fimbrial adhesins, transport, genetic mobile elements and patogenicity genes were differentially expressed in Pera variety. On the other hand, in the cultivar Navelina ISA 315, more genes related to stress response, detoxification of oxygen reactive species or other substances, “heat shock” proteins, as well as an adhesin of the hemagglutinin type, suggesting differences in cellular aggregation and biofilm composition, as well as a higher estress of the bacteria in tolerant cultivar, produced either by plant defenses or by endophitic microorganisms which are competing with X. fastidiosa. This “handmade” DNA microchip was validated by RT-qPCR, and has revealed as a powerful technique for the analysis of global changes in gene expression of X. fastidiosa in sweet orange plants in vivo, generating a more real image of what is happening in nature than in vitro systems which would never reproduce nature conditions exactly. Some hypotheses were raised in this study about patogenicity mechanisms, therefore, more research is still necessary to achieve a better understanding of pathogenicity mechanisms and host-pathogen interactions

Made available in DSpace on 2014-06-11T19:32:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-22Bitstream added on 2014-06-13T19:03:37Z : No. of bitstreams: 1 souza_jam_dr_jabo.pdf: 4083420 bytes, checksum: cb86ca179e1196f514509e27854de1c3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O nitrogênio é o nutriente requerido em maior quantidade para a cultura da soja. Avanços nas pesquisas de melhoramento genético vegetal e microbiologia do solo permitiram expandir o uso de inoculantes comerciais contendo estirpes de Bradyrhizobium japonicum e Bradyrhizobium elkanii. Estas bactérias infectam as raízes da planta e induzem a formação de nódulos, que abrigam a forma bacterióide, diferenciada da bactéria, responsável pela fixação simbiótica do nitrogênio. Informações sobre processos bioquímicos envolvidos no metabolismo da relação simbiótica podem ser adquiridas através de análises globais de expressão gênica. Para esta finalidade, destaca-se a tecnologia de microarranjo de DNA para detecção de genes diferencialmente expressos em larga escala. O objetivo geral deste trabalho foi identificar genes diferencialmente expressos, por meio de microarranjos de DNA, em Bradyrhizobium elkanii SEMIA 587 cultivada em diferentes meios de cultura, RDM (Rhizobia Defined Medium), TY (Triptone-Yeast Medium) e YMB (Yeast-Mannitol Medium), e em bacterióides isolados de nódulos de soja em diferentes períodos de desenvolvimento, 13, 28 e 48 dias após inoculação. Para esta finalidade, a partir do seqüenciamento de DNA genômico de B. elkanii, um microarranjo (Be587) foi gerado contendo 2654 genes. Em meio RDM, a bactéria confrontou-se com a necessidade de se adaptar e sintetizar suas subunidades formadoras de macromoléculas a partir de uma única fonte de carbono, refletindo em um metabolismo mais ativo nas fases lag e log. Por outro lado, em meio TY, as células cultivadas na presença de uma boa fonte de carbono e energia cresceram rapidamente esgotando os recursos disponíveis no meio, 8 o que pode ter causado uma situação de estresse que se refletiu na identificação... / Nitrogen is the most required nutrient by soybean culture. Advanced researches in genetic plant breeding and soil microbiology allowed the expansion in commercial inoculants applications containing strains of Bradyrhizobium japonicum and Bradyrhizobium elkanii. These bacteria infect plant roots and induce nodule formation which home the differentiated bacteria, named bacteroid. The bacteroid in turn is responsible for symbiotic nitrogen fixation. Biochemical knowledge about processes of symbiotic regulation can be acquired by global analysis of gene expression. To achieve such information, the DNA microarray technology, used for detection of differentially expressed genes in large scale, was used. The purpose of this work was identificate differentially expressed genes of Bradyrhizobium elkanii SEMIA 587, grown under different media conditions, such as RDM (Rhizobia Defined Medium), TY (Triptone- Yeast Medium) and YMB (Yeast-Mannitol Medium), and in bacteroids from soybean nodules at different developmental stages, 13, 28 e 49 days after inoculation. For this purpose, the DNA microarray Be587 with 2654 genes was generated from B. elkanii genomic DNA. In RDM medium the bacterium was confronted with the need of adaptation and building of macromolecules subunits from a single carbon source, what was reflected in a more active metabolism in lag and log phases. In turn, in TY medium with good carbon and energy sources the cells grew fastly and exhaust the medium sources available. Such condition can submitted the bacterial cells to a stress condition that reflected in the identification of higher number differentially expressed genes. At different bacteroids stages, the analysis detected genes related to nodulation and 10 nitrogen fixation regulation more than structural genes. Inasmuch, an organic nitrogen recycle might be involved... (Complete abstract, click electronic access below)

abstract: Enzymes which regulate the metabolic reactions for sustaining all living things, are the engines of life. The discovery of molecules that are able to control enzyme activity is of great interest for therapeutics and the biocatalysis industry. Peptides are promising enzyme modulators due to their large chemical diversity and the existence of well-established methods for library synthesis. Microarrays represent a powerful tool for screening thousands of molecules, on a small chip, for candidates that interact with enzymes and modulate their functions. In this work, a method is presented for screening high-density arrays to discover peptides that bind and modulate enzyme activity. A viscous polyvinyl alcohol (PVA) solution was applied to array surfaces to limit the diffusion of product molecules released from enzymatic reactions, allowing the simultaneous measurement of enzyme activity and binding at each peptide feature. For proof of concept, it was possible to identify peptides that bound to horseradish peroxidase (HRP), alkaline phosphatase (APase) and â-galactosidase (â-Gal) and substantially alter their activities by comparing the peptide-enzyme binding levels and bound enzyme activity on microarrays. Several peptides, selected from microarrays, were able to inhibit â-Gal in solution, which demonstrates that behaviors selected from surfaces often transfer to solution. A mechanistic study of inhibition revealed that some of the selected peptides inhibited enzyme activity by binding to enzymes and inducing aggregation. PVA-coated peptide slides can be rapidly analyzed, given an appropriate enzyme assay, and they may also be assayed under various conditions (such as temperature, pH and solvent). I have developed a general method to discover molecules that modulate enzyme activity at desired conditions. As demonstrations, some peptides were able to promote the thermal stability of bound enzyme, which were selected by performing the microarray-based enzyme assay at high temperature. For broad applications, selected peptide ligands were used to immobilize enzymes on solid surfaces. Compared to conventional methods, enzymes immobilized on peptide-modified surfaces exhibited higher specific activities and stabilities. Peptide-modified surfaces may prove useful for immobilizing enzymes on surfaces with optimized orientation, location and performance, which are of great interest to the biocatalysis industry. / Dissertation/Thesis / Ph.D. Chemistry 2010

Title: Multidimensional statistics and applications to study genes Author: Mgr. Peter Bubelíny Department: Department of probability and mathematical statistics Supervisor: prof. Lev Klebanov, DrSc., KPMS MFF UK Abstract: Microarray data of gene expressions consist of thousands of genes and just some tens of observations. Moreover, genes are highly correlated between themselves and contain systematic errors. Hence the magnitude of these data does not afford us to estimate their correlation structure. In many statistical problems with microarray data, we have to test some thousands of hypotheses simultaneously. Due to dependence between genes, p-values of these hypotheses are dependent as well. In this work, we compared conve- nient multiple testing procedures reasonable for dependent hypotheses. The common manner to make microarray data more uncorrelated and partially eliminate systematic errors is normalizing them. We proposed some new normalizations and studied how different normalizations influence hypothe- ses testing. Moreover, we compared tests for finding differentially expressed genes or gene sets and identified some interesting properties of some tests such as bias of two-sample Kolmogorov-Smirnov test and interesting behav- ior of Hotelling's test for dependent components of observations. In the end of...

Un système est dit robuste s'il est possible de garantir son bon comportement Le cancer est en passe de devenir la première cause de décès dans le monde avec un nombre de cas de cancer qui a pratiquement doublé sur les trente dernières années. Le diagnostic du cancer est d’autant plus important qu’il est maintenant reconnu que, plus la prise en charge du patient est rapide, plus les traitements thérapeutiques sont efficaces. Ce diagnostic doit être précis, fiable, et établi dans les premiers stades de la maladie afin d’augmenter significativement les chances de succès du/des traitements. Les techniques conventionnelles pour le diagnostic du cancer sont essentiellement basées sur des techniques d’imagerie (radiographies, IRM…) associés à des tests cytologiques et biochimiques. Avec le développement récent des technologies de biologie moléculaire (et notamment en protéomique), de nombreux marqueurs tumoraux ont été identifiés et sont utilisés dans des tests d’immunoassay pour le diagnostic voire pronostic du cancer en oncologie clinique. Cependant, le faible taux de marqueurs tumoraux dans le sérum de patient, ainsi que leur grande diversité, sont un challenge important pour l’établissement d’un diagnostic d’autant plus que les techniques de détection souffrent souvent d’un manque de sensibilité et de sélectivité. De plus, du fait de la diversité et de la variabilité des cancers, aucun marqueur tumoral n’est suffisamment spécifique pour permettre un diagnostic précis. Aussi, afin d’augmenter la fiabilité et la précision du diagnostic, il est nécessaire d’utiliser plusieurs marqueurs tumoraux. Dans ce contexte, grâce à leur capacité d’analyse haut débit en parallèle et le faible volume d’échantillon nécessaire, les technologies de puces à protéines (protein microarray)présentent de nombreux avantages pour l’identification de marqueurs tumoraux associés à la réponse humorale. Comme les marqueurs tumoraux sont souvent présents dans les échantillons en très faible quantité (à l’échelle sub micro-molaire), il y a un besoin urgent de développer des puces à protéines avec une détection ultrasensible de marqueurs tumoraux. La spécificité du diagnostic sera fortement liée au choix des protéines que l’on veut détecter(notées protéines cibles) et par conséquent au choix des protéines sondes que l’on va immobiliser sur le support. Un des paramètres critiques dans le développement de puces à protéines sensibles est la chimie de surface qui détermine le mode d’immobilisation de la protéine sonde sur le support et influence son activité biologique et donc sa capacité à reconnaitre et interagir avec la protéine cible que l’on cherche à détecter. Comme de nombreuses études suggèrent qu’un seul biomarqueur n’est pas suffisamment spécifique et sensible, la recherche d’une combinaison pertinente de biomarqueurs est un axe important pour l’amélioration d’un tel diagnostic. L’objectif de ce travail de thèse est donc le développement d’un outil original basé sur la technologie de puces à protéines fonctionnalisées avec différentes chimies de surface pour la détection sensible et spécifique de biomarqueurs tumoraux afin d’améliorer le diagnostic du cancer. Deux types de puces à protéines seront développés pour des applications différentes. Une première puce, avec comme protéines sondes des anticorps, sera développée pour la détection de biomarqueurs tumoraux impliqués dans le cancer colorectal. Une deuxième puce, où les protéines sondes seront des antigènes, sera étudiée en vue de l’identification de réponses autoimmunes de patientes atteintes d’un cancer du sein. [...] / Protein microarrays are becoming powerful tools to screen and identify tumor markers for cancer diagnosis, because of the multiplex detection and minute volume of sample requirement. Due to the diversity and variation in different cancers, no single tumor marker is sensitive and specific enough to meet strict diagnostic criteria. Therefore, a combination of tumor markers is required to increase sensitivity and to establish distinct patterns to increase specificity. To obtain reliable tests, the development of reproducible surface chemistry and immobilization procedure are crucial steps in the elaboration of efficient protein microarrays. In this thesis, 3D micro-structured glass slides were functionalized with various surface chemistries like silane monolayer (amino, epoxy and carboxy), and polymer layers of Jeff amine, chitosan, carboxymethyl dextran (CMD), maleic anhydride-alt-methyl vinyl ether copolymer (MAMVE) for physical adsorption or covalent binding with proteins. Surface characterizations, such as X-ray photoelectron spectroscopy (XPS) and Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), confirmed the monolayer/polymer grafting on the glass slides. Colorimetric assay for determining amine density of three aminated surfaces demonstrated that APDMES had more grafting density than Jeffamine and chitosan. Contact angle measurements show that polymer surfaces were more hydrophilic than monolayer surfaces due to the increasing dosages of polar functional groups. Moreover, the parameters such as additives and pH of spotting buffer, probe concentration, blocking procedures etc, were optimized for tumor marker detection. Under the optimized conditions, antibody microarrays were validated with purified tumor antigens. The best analytical performances obtained for each tumor antigen tested were strongly dependent on functionalized surfaces, e.g. MAMVE exhibited best analytical performances for CEA andHsp60 while NHS leads to best results for PDI and CA19-9. Besides, the implemented antibody microarrays were applied to tumor marker detection from colorectal cancer sera. This evaluation shows the interest to combine several tumor markers on the same surface and the combination of tumor markers on their specific surface lead to remarkably increase the positive responses of tested cancer sera (even up to 100 %). A second type of microarrays (tumor-associated antigens - TAA microarrays) was designed to discriminate breast cancer patients from healthy donors through the detection of tumor autoantibodies. This study included a cohort of 29 breast cancer patients’ and 28 healthy donors’ sera. A panel of fiveTAAs (Hsp60, p53, Her2, NY-ESO-1 and Hsp70) immobilized on their respective optimized surface chemistry allowed to specifically detect over 82% of breast cancer patients.

Orientador: Danilo Moretti-Ferreira / Banca: Claudia Aparecida Rainho / Banca: Ligia Maria Suppo Souza Rúgulo / Banca: Célia Maria Giacheti / Banca: Ester Silveira Ramos / Resumo: A síndrome de Williams-Beuren (SWB) é uma afecção genética rara, com frequência estimada em 1:7500 nascidos vivos, caracterizada por alterações do desenvolvimento associados a deficiência mental moderada, anomalias cardíacas e fácies peculiar, além de um comportamento amigável, alegre e desinibido. O diagnóstico clínico é bastante acurado, porém as diferenças fenotípicas conforme a idade pode dificultar o diagnóstico. O diagnóstico clínico pode ser confirmado pelo diagnóstico molecular, sendo a técnica de FISH, o padrão ouro deste diagnóstico. A SWB tem por etiologia a deleção em 7q11.23, sendo esta ocorrência esporádica. A deleção típica envolve uma região cromossômica de 1.5 Mb ou 1.8 Mb contendo 28 genes denominada de região crítica da SWB. O mecanismo de deleção está ligado as duplicações segmentarias (DSs) ou repetições com baixo números de cópias LCRs. A origem da deleção tem sido atribuída ao rearranjo desigual na meiose devido as recombinações homologas não alélicas (Nonallelic homologous recombination-NAHRs), que pode ocorrer entre regiões repetidas de baixo número de cópias (LCRs). Para termos a indicação ou não da realização do exame de FISH, existem na literatura 3 sistemas de pontuações (escores), publicados por Lowery et al,1997, AAP, 2001 e Sugayama et al, 2007. O presente estudo teve como um dos seus objetivos a verificação da especificidade e da sensibilidade dentre os 3 sistemas publicados, para termos a indicação de qual seria o melhor a ser aplicado. Para tanto foram utilizados um banco de características clínicas com 250 pacientes que já haviam realizados exames da FISH e onde foram aplicados os 3 sistemas de escores. Todos os três sistemas de escores apresentaram alta sensibilidade e baixa especificidade, porém o escore descrito por Lowery et al., 1995 foi ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Williams - Beuren syndrome (WBS ) is a rare genetic disorder , often estimated at 1:7500 live births , characterized by developmental disorders associated with moderate mental retardation , cardiac anomalies and peculiar facies , and a friendly demeanor , cheerful and uninhibited . The clinical diagnosis is fairly accurate, but the phenotypic differences according to age can make diagnosis difficult. The clinical diagnosis can be confirmed by molecular diagnosis, and the technique of FISH, the gold standard for this diagnosis . The SWB is etiology deletion in 7q11.23, which is sporadic. The typical deletion involves a chromosomal region of 1.5 Mb or 1.8 Mb containing 28 genes designated critical region of SWB. The mechanism of deletion is linked to segmental duplications (SDs) or repetitions with low copy numbers of LCRs. The origin of the deletion has been attributed to unequal rearrangement in meiosis because nonallelic homologous recombination (NAHRs), which can occur from repeated regions of low copy number (LCRs). To get an indication whether or not the examination of FISH, in literature there are 3 systems scores (scores), published by Lowery et al, 1997, AAP, 2001 and Sugayama et al, 2007. The present study had as one of its objectives to verify the specificity and sensitivity among 3 systems publish, to terms to indicate what would best be applied. Therefore, we used a database of clinical characteristics of 250 patients who had already performed the FISH tests were applied and where the three scoring systems. All the three scoring systems showed high sensitivity and low specificity, but the score described powder Lowery et al., 1995 was considered the easiest application. The second objective of this study was to evaluate the sizes of the fragments deleted in order to infer the local break points. Thus were studied for the first time in the literature,...(Complete abstract click electronic access below) / Doutor

The mammalian Y chromosome contains genes important for male sexual maturity and reproduction. The mouse Y chromosome long arm harbours a number of multi-copy genes whose absence or reduced representation has been linked to sperm defects and offspring sex ratio distortion in favour of females. Understanding the biological mechanisms of sex ratio distortion and related sperm aberrations could not only result in benefits for fertility research, but also in the development of methods for large scale animal breeding pre-implantation sex selection. The distortion has been linked to an intragenomic conflict between the X and Y chromosomes that impacts spermiogenesis. Since the proportion of X- and Y-bearing sperm does not differ in affected animals, and there is no selective destruction of male embryos post-fertilisation, a functional difference must exist between the X- and Y-bearing sperm. This thesis describes the investigation into the physiological and molecular mechanisms of a large Y-chromosome long arm deletion in the mouse model MF1XYRIIIqdel. The examination of physiological characteristics revealed a distinct sperm morphology within the deletion model. Detailed characterisation of sperm shape demonstrated that aberrations consistently occur within specific regions of the sperm head, linking the distorted morphology to particular maturation stages in the sperm cycle. Using sperm fluorescence in situ hybridisation, a novel and detailed comparison of X- and Y- bearing sperm has shown that a subtle distinction in shape also exists between the X- and Y- bearing sperm in the deletion model. Breeding data were examined and showed a skew towards female offspring and a slightly reduced litter size. Sperm enzyme activity assays did not reveal altered hyaluronidase activity in MF1XYRIIIqdel sperm. Physiological differences between X- and Y- bearing sperm must result from differential gene expression, complicated by the syncitial nature of sperm development. To explore this, a detailed molecular characterisation of the MF1XYRIIIqdel phenotype in developing haploid spermatids was performed. Cellular elutriation and fractionation techniques were employed to separate spermatids at different stages of maturation and isolate different subcellular compartments. Differences in the transcriptional profile between these populations were analysed by microarray and RNA sequencing analysis of total and micro RNA. This work yielded a collection of coding and non-coding transcripts which show distinctive expression and compartmentalisation differences between the deletion model and its wild-type counterpart across several sperm maturation stages. Combining these strategies has led to the identification of several gene products potentially implicated in observed physiological differences and the offspring sex ratio skew, providing candidate genes for further research.

Mesenchymal stem cells are the stem cells that replace the bone, fat and cartilage tissues of the human body. In addition, these cells can form muscles, ligaments and neurons. This wide multipotency has made mesenchymal stem cells of particular interest in the fields of tissue engineering and regenerative medicine. Furthermore, mesenchymal stem cells can modulate the immune system by reducing factors that increase inflammation and immune recognition. This immune recognition suppression has resulted in their application as part of bone marrow transplantation in the prevention of 'graft versus host‘ disease. There are hundreds of on-going clinical trials using these cells for the treatment of autoimmune diseases such as type I diabetes, arthritis and multiple sclerosis. The increasing importance of these cells has brought in to focus the culture methods used to for their expansion and manipulation. Currently, animal derived components are used as surfaces for their growth and as components in the culture media. This exposes these cells to animal pathogens and antigens that can be passed to the recipients of these cells. In the first part of this thesis, polymer microarrays were employed to identify alternatives to the biological surfaces currently used for mesenchymal stem cell culture. This platform allowed hundreds of polyacrylates/acrylamides and polyurethanes to be simultaneously scrutinised to identify surfaces that could support their growth and maintain their stem cell characteristics. Identified polymer surfaces were monitored in long-term culture (10 passages) and were shown to retain the cell phenotype and capacity to differentiate, thus providing chemically defined substrates for long-term mesenchymal stem cell culture. In the second part of this thesis, a 'smart‘ polymer microarray of hydrophilic cross-linked polymers (hydrogels) were used to remove another key biological component of culture, trypsin. These 'smart‘ hydrogels modulated their properties depending on the temperature. Hydrogels that could trigger mesenchymal stem cell release after a reduction in temperature were identified. A unique passaging system using a modest temperature reduction for 1h was developed as a passaging method. Cells were maintained and monitored for 10 passages using this novel enzyme free passaging method. Analysis of the mesenchymal stem cell phenotype and differentiation capacity revealed this method superior than conventional culturing methods. In the final part of this thesis, a 'knowledge-based‘ small molecule library was designed, which could potentially yield small molecules to manipulate/enhance the mesenchymal stem cell state without the use of biological components. The key protein pathways that control the stem cell state were examine with the bioinformatics tool GeneGo was used to identify compounds that affected these pathways, resulting in selection of 200 small molecules. The effect of the small molecules on the mesenchymal phenotype was examined and 5 small molecules were identified that enhanced the phenotype of these cells. The anti-inflammatory properties associated with the hit compounds led to the investigation of their effects on key surface proteins associated with the immune-modulatory state of the cells. In this preliminary study, two of the small molecules, estriol and spermine, increased the expression of a key mesenchymal stem cell marker STRO-1 and down regulated ICAM-1, a critical component of the immune modulation capacity of this cell type.

P. falciparum est le principal responsable des formes graves du paludisme. Le parasiteévolue entre deux hôtes (homme et moustique) qui lui imposent différents environnements; ettout particulièrement, des modifications des pressions partielles d’O2 nécessitant des capacitésd’adaptation surprenantes pour un parasite microaérophile. Chez l’hôte vertébré, lesphénomènes de cytoadhésion, ralentissant la progression du parasite notamment au niveau despoumons, augmentent la durée d’exposition aux conditions hyperoxiques.La dynamique de la réponse parasitaire à l’hyperoxie a été étudiée par une approchecombinée de transcriptomique et de protéomique. Certains mécanismes de défense contre lesespèces réactives d’oxygène ont été appréciés, dont une éventuelle fonction oxydasealternative.L’exposition du parasite à 21% d’O2 induit un retard de croissance au niveau de laschizogonie. Le stress oxydatif induit par l’hyperoxie entraîne des perturbations métaboliquescomme une inhibition de la glycolyse en faveur de la respiration et un ralentissement dumétabolisme de la vacuole digestive. Cette action combinée sur le métabolisme mitochondrialet vacuolaire permet au parasite de s’adapter à un environnement hyperoxydant, en régulant laproduction d’espèces réactives d’oxygène. Nos travaux ont montré qu’un inhibiteur de lafonction oxydase alternative, l’acide salicylhydroxamique ou SHAM, avec un effet mineur surla croissance parasitaire en microaérophilie, avait un effet létal sur les parasites en hyperoxie.Une meilleure compréhension de la biologie parasitaire pourrait contribuer audéveloppement de nouveaux traitements antipaludiques associés à une thérapie hyperbarique. / P. falciparum is the main species responsible for severe case of malaria. The parasiteevolves between two hosts (human and mosquito), imposing to it different environments;especially changes in the O2 pressure, demanding astonishing adaptation skills for amicroaerophilic parasite. In the vertebrate host, the phenomena of cytoadhesion, which slowdown the spread of the parasite among others in the lungs, increase the timing of exposure tohyperoxic conditions.The parasitic response dynamic to hyperoxia has been analysed by a combinedtranscriptomic and proteomic approach. Some of the defense mechanisms against reactiveoxygen species have been evaluated, among which a potential alternative oxidase function.The exposure of the parasite to 21%O2 atmosphere leads to a growth delay atschizogony level. The oxidative stress resulting from the hyperoxia conducts to metabolicalterations, as an inhibition of the glycolysis in favour of respiration and as a slowdown of themetabolism of the digestive vacuole. This combined action on the mitochondrial and vacuolarmetabolisms allows the parasite to adapt itself to hyperoxic environment, by regulatingreactive oxygen species. Our works have shown that an inhibitor of the alternative oxidasefunction, the salicylhydroxamic acid or SHAM, with a minor effect on the parasite growth inmicroaerophily, had letal effect on parasites in hyperoxia.A better understanding of the parasitic biology could contribute to the development ofnew antimalarial treatments, associated with a hyperbaric oxygen therapy.