A Araucaria angustifólia é uma conífera nativa do Brasil que apresenta sementes recalcitrantes. Devido a sua importância econômica, foi intensamente explorada ao longo dos anos, encontrando-se atualmente classificada como espécie em perigo crítico de extinção pela International Union for Conservation of Nature. A embriogênese somática apresenta-se como uma ferramenta biotecnológica de grande valia na propagação de espécies recalcitrantes e de difícil propagação, com aplicação em programas de conservação, reflorestamento, e melhoramento genético vegetal. Estudos comparativos dos processos de embriogênese somática e zigótica têm permitido o conhecimento dos fatores bioquímicos, fisiológicos e genéticos que controlam o desenvolvimento do embrião, e o estabelecimento as condições artificiais para o correto desenvolvimento embrionário in vitro. O objetivo deste trabalho foi estudar a participação do ácido salicílico como sinalizador do processo de embriogênese zigótica e somática em A. angustifólia. Para tanto foi determinado o conteúdo de ácido salicílico livre e conjugado ao longo da embriogênese zigótica, e o efeito de sua suplementação em culturas embriogênicas com diferentes potenciais para a maturação. Para a embriogênese somática, a presença do ácido salicílico foi correlacionada com a geração de óxido nítrico e espécies reativas de oxigênio , e com a expressão do gene \"Somatic Embryogenesis Receptor Kinase\" (AaSERK). Os resultados obtidos demonstram que: a) ocorre um maior conteúdo de ácido salicílico na forma livre e conjugada nas etapas iniciais da embriogênese zigótica; b) a suplementação de ácido salicílico, nas concentrações de 0,5 a 2 mM, inibiram a indução de culturas embriogênicas; c) culturas embriogênicas incubadas em ácido salicílico apresentaram redução da síntese endógena de espécies reativas de oxigênio e aumento no conteúdo de óxido nítrico; d) a redução de espécies reativas de oxigênio indicou uma relação dose dependente com o ácido salicílico; e) a adição de um doador de óxido nítrico e um sequestrador inibiram a produção de espécies reativas de oxigênio; f) a expressão do gene AaSERK atingiu o maior nível no período de quatro horas de incubação em 0,1 mM de AS / Araucaria angustifolia is a conifer native of Brazil with recalcitrant seeds. Due to its economic importance, the exploration has been extensively over the years, currently this specie is classified as critically endangered by the International Union for Conservation of Nature. Somatic embryogenesis is presented as a biotechnological tool of great value in the propagation of recalcitrant species and difficult to spread, with applications in conservation, reforestation programs, and plant breeding. Comparative studies of the processes of zygotic and somatic embryogenesis has allowed the knowledge of biochemical, physiological and genetic factors that control embryo development, and the establishment artificial conditions for proper embryonic development in vitro. The objective of this work was to study the role of salicylic acid as a marker of zygotic embryogenesis and somatic process in A. angustifolia. Thus, we determined the content of free salicylic acid and conjugated along the zygotic embryogenesis, and the effect of their supplementation with different potential embryogenic cultures for maturation. For somatic embryogenesis, the presence of salicylic acid was correlated with the generation of nitric oxide, reactive oxygen species and in the gene expression \"Somatic embryogenesis Receptor Kinase\" (AaSERK). The results show that: a) there is an increased content of salicylic acid in free and conjugated form in the initial stages of zygotic embryogenesis; b) salicylic acid supplementation, in concentrations from 0.5 to 2 mM, inhibited the induction of embryogenic cultures; c) embryos incubated in salicylic acid decreased endogenous synthesis of reactive oxygen species and increase in content of nitric oxide; d) the reduction of reactive oxygen species indicated a dose-dependent relationship with salicylic acid; e) the addition of a nitric oxide donor and a kidnapper inhibited the production of reactive oxygen species; f) the expression of the gene AaSERK reached the highest level in four hours of incubation in 0.1 mM AS

by Yau Ming Hon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 131-154). / Abstracts in English and Chinese. / Contents --- p.i / Acknowledgements --- p.ix / Abstract --- p.x / 槪論 --- p.xi / List of abbreviations --- p.xii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Reactive oxygen species (ROS) --- p.2 / Chapter 1.1.1 --- Hydrogen peroxide --- p.2 / Chapter 1.1.2 --- Superoxide anion --- p.3 / Chapter 1.1.3 --- Hydroxyl radical --- p.3 / Chapter 1.1.4 --- Carbon centered radical --- p.4 / Chapter 1.1.5 --- Nitric oxide --- p.4 / Chapter 1.2 --- Physiological roles of ROS --- p.5 / Chapter 1.2.1 --- Signal transduction --- p.5 / Chapter 1.2.2 --- Phagocytic activity --- p.6 / Chapter 1.3 --- Defense systems against ROS --- p.7 / Chapter 1.3.1 --- Endogenous antioxidant enzymes --- p.8 / Chapter 1.3.1.1 --- Catalase --- p.8 / Chapter 1.3.1.2 --- Superoxide dismutase --- p.8 / Chapter 1.3.1.3 --- Selenium-glutathione peroxidase --- p.9 / Chapter 1.3.1.4 --- Glutathione reductase --- p.10 / Chapter 1.3.1.5 --- Glutathione-S-transferases --- p.10 / Chapter 1.3.2 --- Non-enzymatic antioxidants --- p.12 / Chapter 1.3.2.1 --- Vitamin E (tocopherols and tocotrienols) --- p.12 / Chapter 1.3.2.2 --- Vitamin C (L-ascorbic acid) --- p.13 / Chapter 1.3.2.3 --- Glutathione --- p.14 / Chapter 1.3.2.4 --- Flavonoids and polyphenols --- p.15 / Chapter 1.3.2.5 --- Uric acid --- p.16 / Chapter 1.4 --- Roles of ROS in pathogenesis --- p.16 / Chapter 1.4.1 --- Liver diseases --- p.17 / Chapter 1.4.2 --- Genital malfunctioning --- p.19 / Chapter 1.5 --- "The traditional Chinese medicinal formula, Wu-zi-yan-zong-wan" --- p.19 / Chapter 1.5.1 --- Pharmacology of individual herbal components --- p.20 / Chapter 1.5.1.1 --- Semen Cuscuta --- p.20 / Chapter 1.5.1.2 --- Fructus Lycii --- p.21 / Chapter 1.5.1.3 --- Fructus Schisandrae --- p.21 / Chapter 1.5.1.4 --- Fructus Rubi --- p.22 / Chapter 1.5.1.5 --- Semen Plantaginis --- p.22 / Chapter 1.5.2 --- Effect of Wu-zi-yan-zong-wan on infertility --- p.23 / Chapter 1.5.3 --- Effect of Wu-zi-yan-zong-wan on liver disease --- p.23 / Chapter 1.6 --- Objectives of the present study --- p.24 / Chapter Chapter 2 --- Antioxidant Activity of Aqueous Extracts of the Herbal Components of Wu-zi-yan-zong-wan in in vitro Free Radical Generating Systems --- p.26 / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.1.1 --- Application of in vitro ROS generating systems --- p.27 / Chapter 2.1.1.1 --- Superoxide generation --- p.27 / Chapter 2.1.1.2 --- Hydroxyl radical generation system --- p.28 / Chapter 2.1.1.3 --- "2,2'-Azobis(2-amidinopropane) dihydrochloride- induced hemolysis" --- p.28 / Chapter 2.1.1.4 --- Bleomycin-iron-dependent DNA damage --- p.28 / Chapter 2.1.2 --- Objective --- p.29 / Chapter 2.2 --- Materials and methods --- p.30 / Chapter 2.2.1 --- Materials --- p.30 / Chapter 2.2.2 --- Preparation of aqueous herbal extracts --- p.30 / Chapter 2.2.3 --- Superoxide-scavenging assay --- p.30 / Chapter 2.2.4 --- Microsome lipid peroxidation inhibition assay --- p.31 / Chapter 2.2.5 --- "2,2'-Azobis(2-amidinopropane) dihydrochloride-induced hemolysis inhibition assay" --- p.32 / Chapter 2.2.6 --- Bleomycin-iron-dependent DNA damage inhibition assay --- p.32 / Chapter 2.2.7 --- Statistical analysis --- p.33 / Chapter 2.3 --- Results --- p.34 / Chapter 2.3.1 --- Extraction yield --- p.34 / Chapter 2.3.2 --- Free radical scavenging activity of Wu-zi-yan-zong-wan extract --- p.34 / Chapter 2.3.3 --- Free radical scavenging activity of FR extract --- p.37 / Chapter 2.3.3.1 --- Superoxide-scavenging activity --- p.37 / Chapter 2.3.3.2 --- Effect on hydroxyl radical-induced lipid peroxidation --- p.37 / Chapter 2.3.3.3 --- Effect on AAPH-induced hemolysis --- p.40 / Chapter 2.3.3.4 --- Effect on bleomycin-iron-dependent DNA damage --- p.40 / Chapter 2.3.4 --- Pro-oxidant activity of FR extract --- p.40 / Chapter 2.3.5 --- Free radical scavenging activity of the remaining herbal extracts --- p.44 / Chapter 2.4 --- Discussion --- p.46 / Chapter Chapter 3 --- Effect of Aqueous Extract of the Herbal Components of Wu- zi-yan-zong-wan on tert-Butyl Hydroperoxide-Induced Oxidative Damage in Primary Rat Hepatocyte --- p.51 / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.1.1 --- Primary rat hepatocyte as pharmacological model --- p.52 / Chapter 3.1.2 --- tert-Butyl hydroperoxide as an oxidative stress inducer --- p.53 / Chapter 3.1.3 --- Detection of ROS --- p.54 / Chapter 3.1.4 --- Objective --- p.55 / Chapter 3.2 --- Materials and methods --- p.56 / Chapter 3.2.1 --- Materials --- p.56 / Chapter 3.2.2 --- Primary rat hepatocyte isolation --- p.56 / Chapter 3.2.2.1 --- Liver perfusion --- p.56 / Chapter 3.2.2.2 --- Collagen pre-coated plates preparation --- p.57 / Chapter 3.2.2.3 --- Hepatocyte culture --- p.58 / Chapter 3.2.3 --- Drug treatment and oxidative stress induction --- p.58 / Chapter 3.2.4 --- Cytotoxicity assessment --- p.58 / Chapter 3.2.4.1 --- Lactate dehydrogenase leakage measurement --- p.59 / Chapter 3.2.4.2 --- MTT assay --- p.59 / Chapter 3.2.5 --- Cellular GSH content determination --- p.59 / Chapter 3.2.6 --- Protein determination by Lowry's method --- p.60 / Chapter 3.2.7 --- MDA measurement --- p.60 / Chapter 3.2.8 --- GSSG measurement --- p.61 / Chapter 3.2.9 --- ROS measurement with fluorescent dye --- p.61 / Chapter 3.2.10 --- "Vitamin C, vitamin E and butylated hydroxytoluene treatment" --- p.62 / Chapter 3.2.11 --- Antioxidant enzyme activity measurement --- p.62 / Chapter 3.2.11.1 --- Catalase activity measurement --- p.62 / Chapter 3.2.11.2 --- Superoxide dismutase activity measurement --- p.63 / Chapter 3.2.11.3 --- Glutathione peroxidase activity measurement --- p.63 / Chapter 3.2.11.4 --- Glutathione-S-transferases activity measurement --- p.63 / Chapter 3.2.11.5 --- Glutathione reductase activity measurement --- p.64 / Chapter 3.2.12 --- Statistical analysis --- p.64 / Chapter 3.3 --- Results --- p.65 / Chapter 3.3.1 --- Cytotoxicity of FR extract on rat hepatocyte --- p.65 / Chapter 3.3.2 --- Effect of tBHP and FR extract on hepatocyte viability --- p.65 / Chapter 3.3.3 --- Time-dependent effect of FR extract on tBHP-induced cytotoxicity --- p.69 / Chapter 3.3.4 --- Effect of tBHP and FR extract on hepatocyte GSH content --- p.69 / Chapter 3.3.5 --- Effect of tBHP and FR extract on GSSG formation in hepatocyte --- p.72 / Chapter 3.3.6 --- Effect of tBHP and FR extract on MDA formation in hepatocyte --- p.72 / Chapter 3.3.7 --- ROS-scavenging activity of FR extract in hepatocyte --- p.77 / Chapter 3.3.8 --- Effect of FR extract on antioxidant enzymes activities --- p.77 / Chapter 3.3.9 --- Comparison between typical antioxidants --- p.77 / Chapter 3.3.10 --- Effect of WZ and remaining herbal extracts on tBHP-induced oxidative damage in hepatocyte --- p.81 / Chapter 3.4 --- Discussion --- p.84 / Chapter Chapter 4 --- Effect of Aqueous Extract of Wu-zi-yan-zong-wan and Fructus Rubi on tert-Buty Hydroperoxide Induced Oxidative Damage in Mouse Model --- p.91 / Chapter 4.1 --- Introduction --- p.92 / Chapter 4.2 --- Materials and methods --- p.93 / Chapter 4.2.1 --- Materials --- p.93 / Chapter 4.2.2 --- Animal treatments --- p.93 / Chapter 4.2.3 --- Serum preparation --- p.94 / Chapter 4.2.4 --- Marker enzyme measurement --- p.94 / Chapter 4.2.5 --- Liver MDA and GSH determination --- p.95 / Chapter 4.2.6 --- Statistical analysis --- p.95 / Chapter 4.3 --- Results --- p.97 / Chapter 4.3.1 --- Effect of tBHP and FR extract on mouse serum ALT and AST activities --- p.97 / Chapter 4.3.2 --- Effect of tBHP and FR extract on mouse liver MDA and GSH content --- p.97 / Chapter 4.3.3 --- Effect of WZ extract on tBHP-induced increase in serum ALT and AST activities --- p.97 / Chapter 4.4 --- Discussion --- p.102 / Chapter Chapter 5 --- Characterization of the Active Antioxidant Principlein Aqueous Extract of FR --- p.105 / Chapter 5.1 --- Introduction --- p.106 / Chapter 5.2 --- Materials and methods --- p.107 / Chapter 5.2.1 --- Materials --- p.107 / Chapter 5.2.2 --- Chemical/physical treatments on FR extract --- p.107 / Chapter 5.2.3 --- Digestion with enzymes --- p.108 / Chapter 5.2.4 --- Antioxidant activity determination --- p.109 / Chapter 5.2.5 --- Chemical composition determination --- p.109 / Chapter 5.2.5.1 --- Uronic acid determination --- p.109 / Chapter 5.2.5.2 --- Hexose determination --- p.109 / Chapter 5.2.5.3 --- Tannin determination --- p.110 / Chapter 5.2.5.4 --- Protein determination --- p.110 / Chapter 5.2.6 --- Column chromatography --- p.110 / Chapter 5.2.6.1 --- Polyamide CC6 resin column chromatography --- p.111 / Chapter 5.2.6.2 --- Sephadex LH-20 gel column chromatography --- p.111 / Chapter 5.2.7 --- Antioxidant activity of commercially available tannin --- p.111 / Chapter 5.2.8 --- Bovine serum albumin precipitation --- p.112 / Chapter 5.2.9 --- Statistical analysis --- p.112 / Chapter 5.3 --- Results --- p.113 / Chapter 5.3.1 --- Effect of chemical/physical treatments on antioxidant activity of FR extract --- p.113 / Chapter 5.3.2 --- Effect of enzyme digestions on antioxidant activity of FR extract --- p.113 / Chapter 5.3.3 --- Chemical composition of FR extract --- p.118 / Chapter 5.3.4 --- Polyamide CC6 resin column chromatography --- p.118 / Chapter 5.3.5 --- Sephadex LH-20 gel column chromatography --- p.118 / Chapter 5.3.6 --- Antioxidant activity of commercially available tannin --- p.123 / Chapter 5.3.7 --- Effect of BSA precipitation on superoxide-scavenging activity --- p.123 / Chapter 5.4 --- Discussion --- p.127 / Conclusion --- p.131 / References --- p.132

Dietas hiperlipídicas e a esteatose hepática são condições extremamente prevalentes. Trabalhos anteriores mostraram que a esteatose está associada a um aumento na geração de espécies reativas de oxigênio (ERO), e que isso pode mediar danos no fígado. Neste trabalho nós investigamos os possíveis mecanismos que desencadeiam os aumentos nas taxas de geração de ERO por meio da administração de dietas hiperlipídicas. Nós descobrimos que mitocôndrias de animais sujeitos a dietas hiperlipídicas não apresentaram diferenças significativas quanto a capacidade respiratória máxima e acoplamento, mas eram capazes de gerar mais ERO especificamente quando usados substratos do metabolismo de ácidos graxos. Além disso, foi observado que muitas isoformas de acil-CoA desidrogenases estavam mais expressas nos fígados de animais alimentados pela dieta hiperlipídica. No entanto, quando realizados ensaios de atividade enzimática apenas a acil CoA desidrogenase de cadeia longa (VLCAD) foi mais ativa. Estudos conduzidos com mitocôndrias permeabilizadas e expostas a grupos acil-CoA de diferentes tamanhos sugerem que a VLCAD pode ser uma fonte da produção aumentada de ERO em animais submetidos a dietas hiperlipídicas. Esta produção foi estimulada pela ausência de NAD+. Concluindo, nossos estudos descobriram uma nova fonte importante na geração de ERO estimulada por dietas hiperlipídicas, a VLCAD / High fat diets and accompanying hepatic steatosis are highly prevalent conditions. Previous work has shown that steatosis occurs concomitantly with enhanced reactive oxygen species (ROS) generation, which may mediate further liver damage. Here we investigated mechanisms leading to enhanced ROS generation following high fat diets (HFD). We found that mitochondria from HFD livers present no differences in maximal respiratory rates and coupling, but generate more ROS specifically when fatty acids are used as substrates. Indeed, many acyl-CoA dehydrogenase isoforms were found to be more highly expressed in HFD livers, although only the very long chain acyl-CoA dehydrogenase (VLCAD) was more functionally active. Studies conducted with permeabilized mitochondria and different chain length acyl-CoA derivatives suggest that VLCAD is a source of enhanced ROS production in mitochondria from HFD animals. This production is stimulated by the lack of NAD+. Overall, our studies uncover VLCAD as a novel, diet-sensitive, source of mitochondrial ROS

Ce travail montre qu’une protéine non encore décrite dans les phagocytes, la PAT1 « Protein interacting with APP Tail 1 », interagit avec la partie cytosolique de la p22phox (composant du cytochrome b558 membranaire de la NADPH oxydase). Nous avons utilisé différentes approches pour montrer cette interaction : le système double hybride, la technique de GST-pull down, la microscopie confocale et la technique de co-immunoprécipitation. De plus, nous avons montré que la PAT1a recombinante augmente l’activité de la NADPH oxydase, in vitro dans un système acellulaire reconstitué, et dans les cellules intactes (monocytes et cellules COS-phox). Cette nouvelle interaction régule donc l’activation de la NADPH oxydase et la production des FRO. Par ailleurs, la liaison de PAT1 aux microtubules pourrait favoriser l’assemblage du complexe NADPH oxydase pendant son activation. Ceci pourrait conduire à l’identification de nouvelles cibles thérapeutiques qui préviennent la survenue des lésions tissulaires dans les maladies inflammatoires. / Reactive oxygen species (ROS) production by the phagocyte NADPH oxidase plays a crucial role in host defenses. NADPH oxidase is composed of the membrane flavocytochrome b558 components (p22phox and gp91phox/NOX2), and cytosolic components (p40phox, p47phox, p67phox and a small GTPase Rac1 or Rac2). In this work we identified PAT1 by double hybrid system as a potential partner of p22phox. The interaction between p22phox and PAT1a was further confirmed by in vitro GST pull-down assay, confocal microscopy and co-immunoprecipitation. Addition of recombinant PAT1a to the cell free-system enhanced NADPH oxidase activation and it’s over-expression in human monocytes and in COSphox cells increased ROS production in resting and fMLP-stimulated cells.These data clearly identify PAT1 as a novel regulator of NADPH oxidase activation in phagocytes.Inhibition of p22phox/PAT1 interaction could be used as new approach to limit ROS production by phagocytes at inflammatory sites.

Les NADPH oxydases constituent une famille d’enzymes dont la fonction est dédiée à la production de formes réactives de l’oxygène. NOX1, un des membres de cette famille, est abondamment exprimée dans le colon et sa dérégulation pourrait être associée aux maladies inflammatoires chroniques de l’intestin. Les mécanismes qui modulent l’activation de NOX1 demeurent mal connus. Au cours de ma thèse je me suis donc intéressée à l’étude de la phosphorylation de NOXA1 et NOXO1, deux sous-unités régulatrices du complexe NOX1 et ai démontré 1) que la phosphorylation de NOXA1 constitue un mécanisme de régulation négative de l’activité de NOX1 en vue de maintenir l’activité constitutive du complexe à un niveau adéquat et non excessif. 2) pour la première fois, que NOXO1β est phosphorylée et que cette phosphorylation entraîne une hyperactivation de NOX1. L’ensemble de ces données montre que NOX1 est finement régulée. Par ce biais, NOX1 pourrait être impliquée dans la défense anti-infectieuse de l’intestin. / The NOX family of NADPH oxidases are enzymes which function is dedicated to the production of reactive oxygen species. NOX1, a member of this family is expressed abundantly in the intestine and its disregulation could be linked to inflammatory diseases such as inflammatory bowel diseases. However, the molecular basis of NOX1 regulation remains unclear. During my thesis, I demonstrated that 1) NOXA1, the activator cytosolic subunit of the NOX1 complex, is phosphorylated and its phosphorylation prevents hyperactivation of NOX1 in order to maintain a constitutive activity which would not be too excessive. 2) phosphorylation of human NOXO1, the organizer subunit of the complex is a prerequisite of full activation of NOX1. Taken together, these results demonstrate that NOX1 is tightly regulated by phosphorylation events. By this mean, NOX1 could be involved in host immune defense of the intestine.

As espécies reativas de oxigênio são fundamentais na fisiologia espermática. No entanto, um desequilíbrio entre a produção e a capacidade antioxidante caracteriza o estresse oxidativo (EO). O espermatozoide é extremamente suscetível ao EO pois, dentre outras características, a membrana plasmática é rica em ácidos graxos poli-insaturados responsáveis por promoverem a fluidez necessária em processos fisiológicos como motilidade e fertilização. Por outro lado, essas insaturações são mais facilmente oxidadas e vulneráveis à peroxidação lipídica. Em função desta susceptibilidade, estas células dependem fortemente de compostos presentes no plasma seminal (PS) para a proteção contra esse evento. Dessa forma, a carnosina, dipeptídeo presente no PS pode ser uma das responsáveis pela proteção contra o acúmulo do MDA. No entanto, durante a criopreservação do sêmen equino é necessário retirar o PS. Em estudo recente, verificamos que esta remoção, torna os espermatozoides sensíveis ao subproduto extremamente deletério da peroxidação lipídica, o malondialdeído (MDA). Como a carnosina é removida junto com o plasma seminal durante a criopreservação, foram desenvolvidos 2 experimentos sequenciais visando a melhora da qualidade do sêmen criopreservado com adição de carnosina. Amostras de sêmen de sete garanhões foram tratadas com concentrações crescentes de carnosina adicionadas ao diluidor (1mM, 50mM e 100mM). Após a descongelação, as amostras foram divididas retrospectivamente em grupos de alta congelabilidade (AC: motilidade maior que 30%) e baixa congelabilidade (BC: motilidade menor que 30%). Amostras tratadas com 50mM apresentaram menor porcentagem de células com lesão de membrana plasmática e, quando tratadas com 100mM, células com maior amplitude do deslocamento lateral de cabeça. Amostras controle BC apresentaram menor porcentagem de células com DNA íntegro em relação às amostras AC. No entanto, houve um leve aumento na porcentagem de células com DNA íntegro em amostras BC com 100mM, não diferindo das amostras AC. Por outro lado, amostras BC criopreservadas com 50mM apresentaram maiores porcentagens de células com escore calculado de potencial de membrana mitocondrial e mais suscetíveis ao EO em relação ao controle. Apesar da proteção parcial, a maior suscetibilidade à peroxidação lipídica torna-se um problema, especialmente pelo fato de que espermatozoides equinos são mais suscetíveis ao MDA. Um motivo para este efeito seria a afinidade da carnosina em reagir com açúcares, o que poderia influenciar negativamente a atividade mitocondrial e o status oxidativo, ao diminuir a produção de piruvato pela via glicolítica. Desta forma, no experimento 2, amostras BC foram tratadas com a combinação de carnosina (0 e 50mM) e piruvato (0 e 5mM) em arranjo fatorial 2x2. Verificou-se que o tratamento com piruvato (5mM) proporcionou menos células com baixa atividade mitocondrial. Por outro lado, a carnosina (50mM), promoveu maior motilidade total, progressiva e células rápidas. Houve uma tendência de aumento nas células com velocidade progressiva e atividade mitocondrial na combinação de tratamentos. Não houve diferença entre os grupos na suscetibilidade ao EO que, no entanto, correlacionou-se negativamente com células móveis, rápidas e integridade de membrana plasmática e acrossomal. Estes resultados indicam que subprodutos da peroxidação lipídica, sendo o principal deles o MDA, podem causar danos ao DNA, às mitocôndrias e à cinética espermática. Neste contexto, a carnosina (100mM) parece ter um leve efeito protetor ao DNA contra o acúmulo de MDA. Além disto, 50mM de carnosina parece auxiliar na manutenção da velocidade progressiva e atividade mitocondrial quando associada ao piruvato (5mM). Assim, a carnosina e o piruvato podem ser utilizados na prevenção de crioinjúrias em amostras de baixa congelabilidade. / Reactive oxygen species (ROS) plays a key role in the sperm physiology. However, an imbalance between ROS production and antioxidant capacity characterize the oxidative stress (OE). The spermatozoa are extremely susceptible to EO because, among other characteristics, the plasma membrane is rich in polyunsaturated fatty acids responsible for promoting fluidity necessary in physiological processes such as motility and fertilization. However, these unsaturations are more easily oxidized and vulnerable to lipid peroxidation. Due to this susceptibility, these cells strongly depend on compounds present in the seminal plasma (SP) to protect against this event. Thus, carnosine, a dipeptide present in SP of stallions, may be a key factor on the protection against MDA accumulation. Nevertheless, during the equine sperm cryopreservation process, SP is removed. In a recent study, we observed that seminal plasma removal led to an increased susceptibility of equine spermatozoa to extremely deleterious product of lipid peroxidation, malondialdehyde (MDA). As the carnosine is removed together with the seminal plasma during cryopreservation, two sequential experiments were developed aiming to improve the quality of stallion cryopreserved semen by means of carnosine therapy. Samples from seven stallions were treated with increasing concentrations of carnosine added to the extender (1mM, 50mM and 100mM) and submitted to cryopreservation. After thawing, samples were classified as high freezeability (HF: total motility greater than 30%) and low freezeability (LF: total motility lower than 30%). Samples treated with 50mM presented lower percentage of sperm showing plasma membrane damage and, when treated with 100mM, a greater amplitude of the lateral head displacement was observed. Untreated LF samples showed a lower percentage of cells showing intact DNA in relation to HF samples. By contrast, when LF samples were treated with 100mM, there was an increase in the percentage of cells with intact DNA, which was similar to the HF samples. On the other hand, LF samples cryopreserved with 50mM had a higher percentage of cells showing high calculated mitochondrial membrane potential score and increased susceptibility to OE in relation to the control. Despite the partial protection, the increased susceptibility to lipid peroxidation is a concern since equine spermatozoa is highly vulnerable to the MDA. Those results could be due to the affinity of carnosine to react with sugars, which could negatively influence mitochondrial activity and an oxidative state by decreasing pyruvate production. Hence, in experiment 2, LF samples were treated with a combination of carnosine (0 and 50mM) and pyruvate (0 and 5mM) in a 2x2 factorial arrangement. We observed that samples treated with pyruvate (5mM) had decreased percentage of cells with low mitochondrial activity. On the other hand, carnosine (50mM) increased total motility, progressive motility and fast cells. We also observed a tendency to increased progressive velocity and mitochondrial activity in the combination of treatments. There was no difference on sperm susceptibility to OE between treatments. However, this variable correlated negatively with the percentage of motile and rapid cells as well as those showing intact membrane and acrosome. These results indicate that the byproduct of lipid peroxidation (MDA) may cause damage to DNA, mitochondria and sperm kinetics. In this context, carnosine (100mM) appears to have a mild protective effect on DNA against the accumulation of MDA. Furthermore, 50mM of carnosine seems to improve progressive velocity and mitochondrial activity when associated with pyruvate (5mM). Thus, carnosine and pyruvate can be used on cryoinjuries prevention in low freezeability samples.

The diagnosis of cancer in early stages is an unmet clinical need, especially in view that current treatments for cancer cannot address metastatic disease. Cancer aberration processes are associated to an increase in the production of reactive oxygen species (ROS). Chemical probes that can specifically detect these species are potentially useful as medical diagnostics and research tools for cancer imaging. One of the aims of my thesis was the design and synthesis of the activatable fluorescent probes based on small molecule fluorophores modified with chemically reactive moieties. The activation of these moieties by defined targets (e.g. ROS) results in the activation of the fluorophore and subsequent emission of a fluorescent signal. Two libraries of fluorescence probes for the detection of ROS have been designed and synthesised: 1) hydrocyanine-based probes as silent fluorophores that can be activated with superoxide ions, 2) coumarin-based hydrogen peroxide probes with red-shifted fluorescent properties and different boronate activatable groups for hydrogen peroxide sensing. We have performed in vitro assays to evaluate the fluorescence response of our probes as well as experiments in relevant live cells to assess their application for detection of ROS in live cells with molecular resolution. Moreover, cancer cells also overexpress Epidermal Growth Factor Receptors (EGFR). Surface-enhanced Raman scattering (SERS) nanotags that can recognize specifically EGFR receptors in cells are promising tools for the enhanced diagnosis of cancer. Two near-infrared cyanine Raman reporters were synthesized with a carboxylic group that was conjugated to cysteamine for derivatization of gold nanoparticles (AuNPs). This work was performed in the CSIR-NIIST (Kerala, India), where I did a 3-month PhD placement. I conjugated the cyanine reporters to spherical AuNPs of 40 nm diameter, and measured their Raman intensity and stability. The best SERS nanotags were selected for encapsulation with PEG and subsequently derivatization with anti-EGFR-EP22 antibodies. In vitro characterization of the SERS nanotags was performed: SERS and absorbance spectra, electron microscopy images as well as SERS imaging experiments in A549 lung cancer cells.

Les biofilms en industries agroalimentaires (IAA) représentent un problème récurrent aux conséquences économiques et de sécurité sanitaire. Le développement de surfaces photoactives aux propriétés antibactériennes pourrait faciliter leur élimination. Une solution serait de déposer une couche mince de dioxyde de titane (TiO2) sur des matériaux rencontrés dans les IAA. Les objectifs de cette thèse ont donc été d’optimiser des couches minces de TiO2 aux propriétés antibactériennes et d’étudier les mécanismes impliqués dans la photocatalyse. Les dépôts sont réalisés par pulvérisation cathodique radiofréquence dans différentes conditions (température, PO2, durée), d’abord sur substrat de verre puis sur acier inoxydable 316La caractérisation des couches minces par microscopie à balayage, diffraction des rayons X, a montré des différences dues au changement de substrat. Les différentes optimisations ont conduit à l’obtention de couches minces possédant une activité photocatalytique et des propriétés antibactériennes sur des souches représentatives de la flore retrouvée dans les IAA de la filière « viande » : L. monocytogenes, Y. enterocolitica et P. fragi. Des diminutions de la population bactérienne entre 1,5Log et 3Log ont été observées. La production d’espèces réactives de l’oxygène (H2O2, ¿OH, O2-¿) a été étudiée par des méthodes spectrocolorimétriques. L’H2O2 à la surface de la couche mince serait converti en ¿OH. L’étude des mécanismes de réponse de L. monocytogenes face à la photocatalyse des couches minces a été initiée par une approche transcriptomique, en suivant l’exp / Biofilms in food industries represent a recurrent problem with economic and health safety implications. The development of photoactive surfaces with antibacterial properties could facilitate their elimination. One solution would be to deposit a thin layer of titanium dioxide (TiO2) on conventional materials used in food plants. The objectives of this thesis were the optimization of thin films of TiO2 with antibacterial properties and to study the mechanisms involved in photocatalysis. Deposits were made by radio-frequency sputtering under different conditions (temperature, oxygen partial pressure, duration), first on a glass substrate and then on 316 stainless steel. Characterization of thin layers by scanning microscopy, diffraction of X-ray, showed differences due to substrate changeTiO2 thin layers obtained either on glass or stainless steel showed photocatalytic and antibacterial properties on representative strains of the flora found in the meat industry: Listeria monocytogenes, Yersinia enterocolitica and Pseudomonas fragi. Decreases in the bacterial population between 1.5Log and 3Log were observed. The production of reactive oxygen species (ROS) was studied by spectrocolorimetric methods. It seems that H2O2 on the surface is converted in another ROS, ¿OH. Finally, the study of the bacterial response mechanisms to photocatalysis, especially for L. monocytogenes, was initiated by a transcriptomic approach by following the expression of genes involved in the response to oxidative stress. However, the method used requires an optimization in order to be used for the bac

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-08-15T11:21:25Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertacao Sebastiao Antonio Mendanha Neto.pdf: 1242328 bytes, checksum: d0f39ae03faaec981292f99cefebb8ea (MD5) / Made available in DSpace on 2014-08-15T11:21:25Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertacao Sebastiao Antonio Mendanha Neto.pdf: 1242328 bytes, checksum: d0f39ae03faaec981292f99cefebb8ea (MD5) Previous issue date: 2010-03-26 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The oxidative stress effects promoted by hydrogen peroxide (H2O2) and 2,2 -Azobis(2- methylpropionamidine)dihydrochloride (AAPH) in proteins and lipids of the erythrocyte membrane were investigated by testing the oxidative hemolysis, the formation of malondialdehyde (MDA) in addition to spectroscopic electron paramagnetic resonance (EPR) of lipid spin label 5-DOXIL stearic acid (5-DSA) and 3-maleimide proxyl (5-MSL) that binds covalently to erythrocyte s membrane proteins. The spectral parameter 2Ak obtained directly from the EPR spectra of spin label 5-DSA structured in the lipid bilayer of the erythrocyte membrane was sensitive to changes in the dynamics of lipids resulting on the oxidation of membrane proteins. The oxidation of proteins observed for very low concentrations of H2O2 (starting at 100 μM) were confirmed with spin label 5-MSL. Lipid peroxidation indicated the oxidative hemolysis and formation of MDA occurred at concentrations of H2O2 about 8 times larger (starting at 800 μM). Ascorbic acid and -tocopherol protect the membrane by hemolysis and MDA tests, but did not prevent the stiffening of the erythrocyte membrane. The spectra of the spin label 5-MSL revealed the existence of two distinct thiol groups in erythrocyte membrane proteins that differ in their structural configurations and sensitivity to oxidative attack. The SH site that has higher exposure to solvent and less reactivity to spin label 5-MSL was the most vulnerable to oxidation. It is well known that upon oxidation hemoglobin binds to the membrane and the results of this study suggest that this effect may be accompanied by a further increase in the parameter 2Ak of the spin label 5-DSA. Catalase present in erythrocytes proved to be an effective protector of lipid peroxidation and oxidation of membrane proteins induced by hydrogen peroxide. / Os efeitos do estresse oxidativo promovido pelo peróxido de hidrogênio (H2O2) e pelo 2,2 -Azobis(2-metilpropanamida) dicloridrato (AAPH) nas prote´ınas e lipídios da membrana de eritrócito foram investigados através do teste da hemólise oxidativa, da formação do malondialde ıdo (MDA) além da espectroscopia de ressonância paramagnética eletrônica (RPE) do marcador de spin lipídico 5-DOXIL estearato (5-DSA) e do marcador de spin 3-maleimida proxil (MAL-5) que se liga covalentemente `as proteínas da membrana de eritrócito. O parâmetro espectral 2Ak obtido diretamente dos espectros de RPE do marcador de spin 5-DSA estruturado na bicamada lipídica da membrana de eritrócito foi sensíıvel `as alterações na dinâmica dos lipídios resultantes da oxidação das proteínas da membrana. A oxidação das proteínas observada para concentrações baixas de H2O2 (a partir de 100 μM) foram confirmadas com o marcador MAL-5. A peroxidação lipídica indicada pela hemólise oxidativa e formação de MDA ocorreu em concentrações de H2O2 cerca de 8 vezes maiores (a partir de 800 μM). O ácido ascórbico e alfa-tocoferol protegem a membrana pelos testes de hemólise e MDA, mas não evitaram o enrijecimento da membrana do eritrócito. Os espectros do marcador MAL-5 revelaram a existência de dois grupos tióis distintos nas proteínas da membrana de eritrócito que diferem quanto a suas configurações estruturais e sensibilidade aos ataques oxidativos. O sítio SH de maior exposiçãoo ao solvente e menor reatividade ao marcador MAL-5 foi o mais vulnerável `a oxidação. É bem conhecido que neste processo oxidativo a hemoglobina se liga à membrana e os resultados deste trabalho sugerem que este efeito pode ser acompanhado por um aumento adicional no parâmetro 2Ak do marcador 5-DSA. A catalase presente nos eritrócitos se revelou como um eficiente protetor da oxidação lipídica e protéica da membrana induzidas por H2O2.

A obesidade desencadeia mudanças estruturais e funcionais no tecido adiposo perivascular (PVAT), levando a um desequilíbrio em favor de substâncias vasoconstritoras e pró- inflamatórias, bem como alterações em suas vias de sinalização no vaso. Um importante mecanismo proposto para explicar a perda do efeito anticontrátil do PVAT na obesidade é o estresse oxidativo. Espécies reativas de oxigênio (EROs) possuem papel importante na modulação da função vascular mediada pelo PVAT. Considerando que a mitocôndria representa fonte potencial de EROs nas células, o presente estudo testou a hipótese que a disfunção mitocondrial no PVAT está envolvida na perda do efeito anticontrátil do PVAT em modelo experimental de obesidade. Este estudo avaliou se a matriz mitocondrial nas células que compõem o tecido adiposo periaórtico representa fonte importante de EROs, e se as mesmas contribuem para as alterações na regulação, pelo PVAT, da reatividade vascular. Nosso estudo demonstrou que animais obesos apresentaram disfunção vascular e perda do efeito anticontrátil do PVAT. O estresse oxidativo está envolvido na disfunção do PVAT, com participação significativa da mitocôndria na geração de EROs, capazes de modular a reatividade vascular. A obesidade favoreceu a disfunção mitocondrial, reduzindo o consumo de oxigênio. Estes eventos favoreceram o aumento na geração de peróxido de hidrogênio mitocondrial no PVAT, o qual prejudica a ação anticontrátil deste tecido por ser ativador direto da via de contração RhoA/Rho cinase / Obesity promotes structural and functional changes in the perivascular adipose tissue (PVAT), favoring the release of vasoconstrictor and proinflammatory substances, as well as altering the vascular signaling pathways activated by PVAT-derived factors. Oxidative stress is an important mechanism proposed to explain the loss of anticontractile effects of the PVAT in obesity. Reactive oxygen species (ROS) play an important role in the modulatory effects of PVAT on vascular function. Considering that mitochondria are a potential source of ROS in the cells, the present study tested the hypothesis that mitochondrial dysfunction leads to the loss of the anticontractile effects of PVAT in obesity. We evaluated whether the mitochondrial matrix of the cells that make up the periaortic fat tissue constitute a major source of ROS, and if mROS contribute to defective regulation of vascular reactivity by the PVAT. Our study shows that obese animals exhibit vascular dysfunction and loss of anticontractile effects of PVAT. Oxidative stress is involved in PVAT dysfunction, with a significant contribution of mitochondria to ROS generation. Obesity promotes mitochondrial dysfunction, reducing oxygen consumption. These events increase the generation of mitochondrial hydrogen peroxide in the PVAT, which impairs the anticontractile effects of this tissue via direct activation of the RhoA / Rho kinase pathway