Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-08-05T10:23:01Z No. of bitstreams: 2 Dissertação - Taise Maria dos Anjos Oliveira - 2016.pdf: 1420716 bytes, checksum: 75628b01c19c9db89c0e4ed2e9469284 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-05T15:03:14Z (GMT) No. of bitstreams: 2 Dissertação - Taise Maria dos Anjos Oliveira - 2016.pdf: 1420716 bytes, checksum: 75628b01c19c9db89c0e4ed2e9469284 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-05T15:03:14Z (GMT). No. of bitstreams: 2 Dissertação - Taise Maria dos Anjos Oliveira - 2016.pdf: 1420716 bytes, checksum: 75628b01c19c9db89c0e4ed2e9469284 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Photodynamic inactivation is a technique based on the synergistic combination of a photosensitizer, light and oxygen, resulting in the generation of reactive oxygen species, which are cytotoxic and cause cell death by apoptosis or necrosis. Bovine herpesvirus 1 is responsible for diseases of the respiratory and reproductive systems, it is estimated to occur an economic loss of a billion dollars a year, due to the action of the virus in the herd. In order to develop new alternatives and /or therapeutic approaches that are effective in viral clearance, we evaluated two photosensitizers, zinc phthalocyanine and aluminum phthalocyanine, the photoinactivation bovine herpesvirus 1. As a control we used irradiated virus without the presence of photosensitizer (light control) viruses incubated with photosensitizers without radiating (photosensitizer control) and viruses without any treatment. The light control showed that the use of light without the presence of photosensitizer does not have phototoxic effect on the virus; control showed that the photosensitizer zinc and aluminum phthalocyanines have no cytotoxicity in the absence of light. Both controls were compared to the virus that received no treatment. To better evaluate the irradiation time and the optimal concentration of the two photosensitizers, viral suspension aliquots containing 105.75 TCID50/mL were used, incubated with photosensitizers at concentrations of 5 and 10 μM and irradiated at 0, 15, 30, 45, 60, 75, and 90 minutes. After irradiation, the sample was added in permissive cell cultures virus, which was analyzed for the presence of cytopathic effect and the results were expressed as viral titers. The zinc phthalocyanine showed better efficiency in photoinactivation bovine herpesvirus 1, wherein the concentration of 10 μM with 30 minutes of irradiation was the most effective. The phthalocyanine aluminum inactivated virus completely after 60 minutes of irradiation, but there was no significant difference between concentrations. These results indicate that both phthalocyanines have a good applicability in photodynamic viral inactivation, but the zinc phthalocyanine has a better efficiency. / A inativação fotodinâmica é uma técnica baseada na combinação sinérgica de um fotossensibilizador, oxigênio e luz, que resulta na geração de espécies reativas do oxigênio, que são citotóxicas e causam a morte celular por apoptose ou necrose. O herpesvírus bovino 1 é responsável por enfermidades no sistema respiratório e reprodutivo, estima-se que ocorra uma perda econômica de um bilhões de dólares por ano, devido à ação do vírus no rebanho. Visando novas alternativas e/ou abordagens terapêuticas que sejam eficazes na eliminação viral, avaliamos dois fotossensibilizadores, ftalocianina zinco e ftalocianina alumínio, na fotoinativação do herpesvírus bovino 1. Como controle foram utilizados vírus irradiado sem a presença do fotossensibilizador (controle da luz), vírus incubado com os fotossensibilizadores sem irradiar (controle do fotossensibilizador) e vírus sem nenhum tratamento. O controle da luz mostrou que o emprego da luz sem a presença do fotossensibilizador não possui efeito fototóxico sobre o vírus, o controle do fotossensibilizador mostrou que as ftalocianinas zinco e alumínio não possuem citotoxidade na ausência da luz. Ambos os controles foram comparados ao vírus que não recebeu nenhum tratamento. Para avaliar o melhor tempo de irradiação e a melhor concentração dos dois fotossensibilizadores, foram utilizadas alíquotas de suspensão viral contendo 105,75 TCID50/mL, incubadas com os fotossensibilizadores nas concentrações de 5 e 10 μM e irradiadas nos tempos 0, 15, 30, 45, 60, 75 e 90 minutos. Após a irradiação a amostra foi adicionada em culturas de células permissíveis ao vírus, onde foi analisada a presença de efeito citopático e os resultados foram expressos em títulos virais. A ftalocianina zinco apresentou melhor eficiência na fotoinativação do herpesvírus bovino 1, sendo a concentração de 10 μM com 30 minutos de irradiação a mais eficaz. A ftalocianina alumínio inativou o vírus totalmente após 60 minutos de irradiação, mas não apresentou diferença significativa entre as concentrações. Estes resultados indicam que ambas ftalocianinas possuem uma boa aplicabilidade na inativação fotodinâmica viral, porém a ftalocianina zinco possui uma melhor eficiência.

Neste trabalho sintetizaram-se novos complexos imínicos e diimínicos de Cu(II) derivados da isatina, um indol endógeno, que foram então extensivamente caracterizados por análise elementar, medidas de condutividade molar, técnicas espectroscópicas: IV, UV/Vis e EPR, e por espectrometria de massa, ESI-MS. Estes compostos apresentaram equilíbrio ceto-enólico em solução, variando a geometria ao redor do íon Cu(II), ao se alterar o pH do meio, indo de tetraédrico em meio ácido à tetragonal em meio básico. Para a elucidação do papel do cobre no mecanismo de oxidação de carboidratos pelo oxigênio molecular, realizaram-se estudos cinéticos tendo como catalisadores estes complexos de cobre. Determinou-se a uma lei cinética global mais abrangente para estas reações, incluindo uma etapa dependente do cobre (a concentrações bem baixas), seguida de outra independente do metal. As etapas no mecanismo proposto, sob condições de pseudo-primeira ordem, combinam transferência eletrônica intramolecular, com provável redução do íon de cobre pelo substrato, levando a espécies muito reativas (OH•-, O2•-, H2O2, CO2•-), responsáveis pelo processo de iniciação e propagação, e a formação de produtos carbonílicos de cadeia curta (glicolato, glicerato e formiato). Para o estudo da interação metal-carboidrato, importante para se entender melhor o papel do cobre frente a este ligante biológico, complexos de Cu(II) com monossacarídeos foram sintetizados e caracterizados por análise elementar e termogravimétrica, medidas de condutividade molar, espectroscopias UV/Vis, IV e EPR, além da espectroscopia Raman, através da qual investigou-se o modo de ligação do carboidrato ao metal em cada um destes complexos. Foram ainda preparados e caracterizados por análise elementar, medidas de condutividade molar, espectroscopias UV/Vis, IV, EPR, ESI-MS e CD dois novos complexos imínicos quirais de Cu(II), com ligantes do tipo aminocarboidrato, e que também foram utilizados para estudos biológicos. Estudos de atividade biológica foram feitos in vitro, usando as linhagens celulares tumorais promonocítica sanguínea U937 e neuroblastoma SH-SY5Y, com os complexos imínicos de cobre, principalmente aqueles derivados da isatina. As células tratadas com os complexos mais ativos sofreram apoptose, verificada por ensaios citofluorimétricos, em que os complexos agiram em diferentes fases do ciclo celular de cada linhagem (fase G1, S ou G2/M). Através da técnica citofluorimétrica foi observada também a geração de radicais livres na célula e, através de ensaios imunológicos, determinou-se a quantidade de proteínas citoplasmáticas carboniladas e glicosiladas, geradas após os tratamentos com os compostos, em diferentes tempos de incubação. De uma maneira geral, estes estudos indicaram modulação da atividade biológica, com um comportamento antiproliferativo muito diferente, indo de baixa eficácia até alta eficiência. Dentre os compostos mais ativos, pode ser observada uma especificidade diferente, tanto com relação ao tipo de célula quanto ao seu modo de ação, evidenciando sua potencial aplicação como agentes antitumorais. / In this work, novel imine and diimine copper(II) complexes with ligands derived from isatin, an endogenous indol, were synthesized, and extensively characterized by elemental analysis, conductivity measurements, spectroscopic techniques (IR, UV/Vis, and EPR), and electrospray mass spectrometry (ESI-MS/MS). These compounds showed a keto-enolic equilibrium in solution, with variations in the geometry around the copper ion with increasing pH, varying from a more tetrahedral configuration in acidic medium to a tetragonal one in basic solution. In order to elucidate the role of copper in the carbohydrate oxidation by molecular oxygen, kinetic studies were performed using these complexes as catalysts. A more comprehensive global rate law was determined for this process, including a copper-dependent pathway (at very low concentrations), in addition to an independent one, both influenced by alkaline medium. The proposed mechanism, under pseudo-first order conditions, combine intramolecular electronic transfer with reduction of the copper ion by the substrate, leading to the formation of intermediary reactive species (OH•-, O2•-, H2O2, CO2•-), responsible for initiation and propagation steps, and of short chain carbonylic products (glycolate, glycerate and formiate ions). To better understanding metal-carbohydrate interactions, copper(II) complexes with simple monosacharides were isolated, and characterized by elemental and thermogravimetric analyses, and spectroscopic techniques (IR, UV/Vis, and EPR), besides Raman spectroscopy, used to investigate the binding mode of the carbohydrate moiety to the copper ion, in each one of these complexes. Additionally, two novel chiral imine copper(II) complexes, derived from aminocarbohydrate ligands, were prepared and characterized by elemental analysis, conductivity measurements, and spectroscopic techniques (IR, UV/Vis, EPR, ESI-MS and CD), and one of them was also used in biological studies. Biological activity studies were carried out with the imine and diimine copper(II) complexes derived from isatin, verifying antiproliferative effect toward some tumor cell lines (promonocite U937 and neuroblastoma SH-SY5Y). Cells treated with the most active complexes were committed by the apoptotic program, as verified by citofluorimetric assays, with the complexes interfering the cell cycle in different ways (G1, G2/M or S phase. Formation of free radicals was detected, and citoplasmatic carbonylated and glycosilated proteins inside the treated cells were determined by imunologic assays. In conclusion, these studies indicated modulation of the biological activity by the imine ligand in the copper(II) complexes, with very different antiproliferative behavior, going from undetectable activity to high efficacy. Among the most active compounds, a different specificity and action mode in both cell type could be observed, evidencing their potential application as antitumoral agents.

Neste trabalho alguns complexos diimínicos de cobre(II) com ligantes do tipo base de Schiff, já estudados em nosso laboratório, além de um novo complexo de zinco foram sintetizados e caracterizados por análise elementar, espectroscopias UV/Vis, Infravermelho e de Ressonância Paramagnética Eletrônica (EPR). Estudos sobre a reatividade destes complexos de cobre(II) frente à oxidação de carboidratos por oxigênio molecular foram então realizados. Estes estudos envolveram várias etapas, com variação das concentrações do catalisador, do substrato e do tampão e variação do pH, verificando-se a influência de cada um destes fatores na cinética de reação. Para tentar entender a interação da albumina bovina (BSA) com os complexos diimínicos de cobre(II) estudados, foram realizados experimentos utilizando-se a técnica de dicroísmo circular e espectroscopia eletrônica. A estabilidade termodinâmica relativa dos vários compostos foi assim determinada, estimando-se os respectivos valores das constantes de estabilidade. Experimentos sobre a atividade oxidante destes complexos frente à albumina bovina, causando danos oxidativos à proteína, também foram efetuados, determinando-se a formação de grupos carbonil na proteína, que foram monitorados espectrofotometricamente, através da obtenção das correspondentes dinitrofenil-hidrazonas, pela reação com dinitrofenil-hidrazina (DNPH). Através da técnica de EPR, foram realizados estudos para a detecção e identificação de espécies radicalares na interação da albumina com os complexos de cobre(II) em presença de peróxido de hidrogênio, com o uso de um captador de spin apropriado. Estudos sobre as possíveis interações dos complexos de cobre(II) com a albumina humana (HSA) e com o plasma sanguíneo foram realizados através das técnicas de EPR e SDS-PAGE. Além disso, a reatividade dos complexos de cobre(II) frente a glutationa, um agente redutor presente em alta concentração no citosol, foi investigada através de experimentos de fluorescência. Finalmente, a influência dos complexos imínicos de cobre(II) sobre a respiração mitocondrial foi investigada, já que estes complexos se mostraram indutores eficientes de apoptose frente a diferentes células tumorais. Para este estudo utilizou-se um oxígrafo para monitorar o consumo de oxigênio durante a respiração mitocondrial, em presença dos complexos de cobre estudados. / In this work some copper(II) complexes with Schiff base ligands, already studied in our laboratory, have been prepared, as well as a new similar zinc complex. After being characterized, especially by spectroscopic techniques (UV/Vis, IR, and EPR), these complexes had their reactivity as catalysts for the oxidation of carbohydrates by molecular oxygen verified. The influence of different factors on the kinetics of reaction, such as variation of the catalyst concentration, substrate concentration, buffer concentration and pH of the solution, was investigated. In order to understand the possible interactions of the copper(II) complexes studied with the protein albumine, studies using CD and electronic spectroscopies were carried out by adding the copper complexes to bovine serum albumine (BSA), and determining the corresponding relative stability constants for each complex. The activity of such copper complexes as oxidant agents toward the protein was also verified, with the formation of carbonyl groups in the protein observed by monitoring spectrophotometrically the corresponding dinitrophenylhydrazones, after reaction with dinitrophenylhydrazine (DNPH). By using EPR spectroscopy and an appropriate spin scavenger, reactive oxygen species were detected and identified as a result of the oxidative damage to the protein occurring in the presence of the copper complexes and hydrogen peroxide. Interactions of the human serum protein (HSA) and human plasma with the copper complexes studied were verified by EPR and SDS-PAGE techniques. Additionally, the reactivity of these complexes toward the reductive agent glutathione, present in the citosol at high concentration, was investigated by fluorescence measurements. Finally, the influence of the complexes in the mitochondrial respiration was verified, since those compounds are able to induce efficiently apoptosis in the presence of different tumoral cells, monitoring the oxygen consumption with a selective oxygen electrode

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-09T12:50:08Z No. of bitstreams: 2 Dissertação - Aline Luciana Rodrigues - 2011.pdf: 1902000 bytes, checksum: f7591f34d543c33bcea4f08d4cb14fa8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-09T14:43:06Z (GMT) No. of bitstreams: 2 Dissertação - Aline Luciana Rodrigues - 2011.pdf: 1902000 bytes, checksum: f7591f34d543c33bcea4f08d4cb14fa8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-09T14:43:06Z (GMT). No. of bitstreams: 2 Dissertação - Aline Luciana Rodrigues - 2011.pdf: 1902000 bytes, checksum: f7591f34d543c33bcea4f08d4cb14fa8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2011-04-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The interest in the preservation of species threatened of extinction has increased the attention for cryopreservation of semen from the epididymis tail of animals that have died. Determination of the time in which the sperm is still viable for preservation represents a benefit for future research and use in animal-assisted breeding programs. In addition, the sperm cryopreservation process results in the production of radical free by the metabolism of the cell causing damage. The objectives of this study were: 1) to determine the viable time interval for cryopreservation of the epididymis tail sperm in cattle, 2) to test the addition of two antioxidants in the freezing media, 3) to determine the viability of semen samples from the tail of the epididymis in the production of embryos by in vitro fertilization. To guarantee the quality of freezing, the parameters: motility, vigor and sperm pathology in the pre-freezing were analyzed. After these assessments the material was divided into three treatments: tris-egg yolk diluent (TTG), Tris-egg yolk diluent catalase (TCAT) and tris-egg yolk diluent trolox (TTROL) and frozen in determined curve by pre-freezing automated process. After thawing, the motility and vigor were evaluated using CASA. Analysis of plasma membrane integrity and acrosome, test resistance thermometer (TTR), thiobarbituric acid reactive substances (TBARS), oxidation of 3,3 'diaminobenzidine (DAB) and in vitro fertilization (IVF) were also evaluated. According to the movement patterns analyzed using CASA, the analysis of data generated by the study allow us to conclude the characteristics of sperm in each treatment and it change on the different times of cooling (0h, 24h, 48h and 72h). In the assessment of integrity (INT) and injured sperm (LS), no statistical differences between the moments or between treatments were observed. Rates of cleavage D7 and D8 were statistically different, at 72 hours the trolox showed negative action. The results shown indicate that this procedure is important for conservation of animals of high genetic value or animals endangered that die suddenly. Further studies should be performed testing associations of antioxidants directly in the middle of fertilization and embryo culture, especially in production systems of embryos with high oxygen tension, as used in this experiment. xxii / O interesse pela preservação de espécies em risco de extinção tem aumentado a atenção pela criopreservação de sêmen da cauda do epidídimo de animais que morrem subitamente. A determinação do momento até quando os espermatozóides estão viáveis para preservação representa um benefício para pesquisas futuras e sua utilização em programas de reprodução animal assistida. Além disso, o processo de criopreservação dos espermatozóides resulta na produção de radicais livres pelo próprio metabolismo desta célula e causando danos. Os objetivos deste estudo foram: 1) determinar o intervalo de viabilidade de resfriamento de espermatozóides da cauda do epidídimo de bovinos, 2) testar o efeito da adição de dois antioxidantes nos meios de congelação, 3) determinar a viabilidade das amostras de sêmen da cauda do epidídimo na produção de embriões por fertilização in vitro. Para garantia da qualidade da congelação foram realizadas análises de motilidade, vigor, patologia espermática, no momento pré-congelação. Após estas avaliações o material foi dividido em três tratamentos: diluente tris-gema-glicerol (TTG), diluente tris-gema-glicerol com catalase (TCAT) e diluente tris-gema-glicerol com trolox (TTROL) e congelados em curva pré-determinada por processo de congelação automatizada. Após a descongelação foram avaliadas a motilidade e vigor com auxílio do CASA, análises de integridade de membrana plasmática e acrossoma, teste de termorresistência (TTR), substâncias reativas ao ácido tiobarbitúrico (TBARs), oxidação da 3,3’ diaminobenzidina (DAB) e fertilização in vitro (FIV). De acordo com os padrões de movimentos observados pelo CASA, a análise dos dados gerados pelo estudo nos possibilitam concluir as características dos espermatozóides em cada tratamento e como se comportaram nos momentos de resfriamento logo após o abate, 24 horas, 48 horas e 72 horas após resfriamento à 5ºC ( 0h, 24h, 48h e 72h). O uso dos antioxidantes não garantiu melhor proteção e nem auxílio na funcionalidade dos espermatozóides do epidídimo nos diferentes períodos de resfriamento. lulas imóveis) não houve diferenças estatísticas. Nas taxas de clivagem D7 e D8 foram observadas diferenças estatísticas, o α-tocoferol no momento 72 h demonstrou ação negativa. Os resultados demonstrados revelaram que tal procedimento é de suma importância para conservação de animais de alto xx valor genético ou animais em risco de extinção que morrem subitamente. Novos estudos devem ser realizados testando associações de antioxidantes ou o uso de antioxidantes diretamente no meio de fecundação e cultivo embrionário, especialmente em sistemas de produção de embriões com alta tensão de oxigênio, como o utilizado neste experimento.

Muitos estudos demonstram que a abertura de canais de K+ mitocondriais sensíveis à ATP (mitoKATP) previnem contra danos promovidos por isquemia/reperfusão em coração. Em geral, esta proteção envolve mudanças no estado redox mitocondrial. Em cérebro, sabe-se que agonistas farmacológicos de mitoKATP também protegem em modelo de isquemia/reperfusão. Entretanto, os mecanismos envolvidos na prevenção de danos em cérebro ainda não estão claros. O objetivo principal deste trabalho é compreender os efeitos de canais de K+ mitocondriais ATP-sensíveis em tecido cerebral e os mecanismos pelos quais a sua ativação pode proteger contra danos promovidos por excitotoxicidade, uma das principais conseqüências de um evento isquêmico em cérebro. Neste contexto, demonstramos a proteção pelo mitoKATP em modelo de excitotoxicidade induzida pela ativação direta de receptores NMDA, utilizando cultura de células granulosas de cerebelo. Paralelamente a essa proteção, verificamos que a ativação de mitoKATP reduz a geração de espécies reativas de oxigênio (ROS). Em mitocôndrias isoladas, observamos que ROS geradas pela mitocôndria ativam mitoKATP cerebral, resultando em um aumento da captação de K+ para a matriz, medida através da técnica de inchamento mitocondrial. Em condições de baixa geração de ROS, a adição de H2O2 exógeno ativa o inchamento mitocondrial em resposta à entrada de K+ de modo prevenido por catalase, assim, confirmando que a atividade desses canais é redox-sensível. A ativação de mitoKATP por agonistas farmacológicos, como diazóxido, também é maior na presença de alta geração de ROS, conforme indicado por uma leve diminuição no potencial de membrana mitocondrial. Interessantemente, a adição de um redutor tiólico, 2-mercaptopropionilglicina (MPG) previne a ativação de mitoKATP. A ativação de mitoKATP não alterou a capacidade de captar Ca2+ pela mitocôndria, demonstrando que este não é o mecanismo pelo qual esses canais previnem morte celular excitotóxica. Não foram observados efeitos desses canais em modelo de excitotoxicidade in vivo e em modelo de doença neurodegenerativa, acidose metilmalônica. Juntos, nossos resultados demonstram que mitoKATP cerebrais agem como sensores de ROS mitocondrial, que quando ativados reduzem a liberação de ROS por um leve desacoplamento, prevenindo morte neuronal por excitotoxicidade NMDA-induzida / Several studies have shown that mitochondrial ATP-sensitive K+ channel (mitoKATP) opening prevents ischemia/reperfusion injuries in heart, in a manner involving changes in redox state. In brain, mitoKATP agonists also protect against ischemia/reperfusion. However, the exactly mechanism that mitoKATP protects the brain is still unclear. The purpose of this work is to understand the effects of mitochondrial ATP-sensitive K+ channels in brain and how this channel can protect against excitotoxic cell death, the main consequence of a cerebral ischemia. In this context, we demonstrate that mitoKATP protects against excitotoxicity promoted by NMDA receptor activation in cultured cerebellar granule cells. In paralell, we verified that mitoKATP activation also decreases reactive oxygen species (ROS). In isolated mitochondria, we observed that mitochondrially-generated ROS can activate brain mitoKATP, resulting in enhanced K+ uptake into the matrix, measured as swelling of the organelle. Under conditions in which mitochondrial ROS release is low, exogenous H2O2 activated swelling secondary to K+ entrance, in a manner prevented by catalase, confirming that the activity of this channel is redox-sensitive. Activation of mitoKATP channels by the pharmacological agonist diazoxide was also improved when endogenous mitochondrial ROS release was enhanced, as indicated by mild decreases in mitochondrial membrane potentials. Interessantly, mitoKATP activation was preveted by the thiol reductant 2-mercaptopropionylglycine (MPG). Mitochondrial Ca2+ uptake was not modified by opening mitoKATP, suggesting that this is not the mechanism through which this channel prevents excitotoxic cell death. In an in vivo excitotoxicity model and also neurodegenerative disease model, methylmalonic acidemia, the effects of mitoKATP agonists were not observed. Together, our results demonstrate that brain mitoKATP acts as a mitochondrial ROS sensor, which, when activated, prevents ROS release by mildly uncoupling respiration from oxidative phosphorylation, decreasing excitotoxic cell death

O nitrogênio é um dos nutrientes que mais altera a produtividade das plantas forrageiras e as formas de fornecimento desse nutriente podem alterar as respostas das plantas. Objetivou-se avaliar as alterações morfogênicas, nutricionais, metabólicas e produtivas do capim tanzânia (Panicum maximum cv. Tanzânia), em função do fornecimento de doses de nitrogênio e proporções de NO3-/NH4+ na solução nutritiva. O experimento foi conduzido em casa de vegetação, com emprego de substrato inerte e avaliando três doses de nitrogênio para fornecer nutrição baixa, intermediária e alta em nitrogênio (3, 15 e 27 mmol L-1) e três proporções de NO3-/NH4+ não fornecendo e até suprindo amônio em relativo excesso (100/0, 70/30 e 40/60). As plantas foram submetidas a dois cortes da parte aérea e as raízes foram coletadas após o segundo corte. Foram avaliados o número de folhas e perfilhos, taxas de aparecimento de folhas e perfilhos, área foliar, produção de massa seca de parte aérea e de raízes, concentrações de nitrogênio total, NO3- e NH4+ nos tecidos vegetais, valor SPAD, concentrações de malondealdeído (MDA) e peróxido de hidrogênio e atividades das enzimas redutase do nitrato, glutamina sintetase, catalase, superóxido dismutase e glutationa redutase. A baixa dose de nitrogênio comprometeu a área foliar e produção de massa seca em ambos os crescimentos do capim tanzânia. O excesso de amônio na solução nutritiva também foi responsável pela área foliar e menor massa de parte aérea e de raízes. Elevadas concentração de MDA e peróxido foram encontrados nos componentes da parte aérea de plantas crescidas sob doses de nitrogênio com proporção de NO3-/NH4+ de 40/60, indicando estresse oxidativo nessas plantas. O estresse ocasionado pelo fornecimento exclusivo da forma nítrica ou pelo excesso de amônio resultou na indução de uma nova banda de SOD no sistema radicular do capim tanzânia, o que sugere que essa enzima tenha sido mais responsiva na eliminação de EROs no sistema radicular. / Nitrogen is one of the nutrients that most improve forage grass productivity and the forms of this nutrient supply may affect plant responses. The objectives were to evaluate morphogenic, nutritional, metabolic and productive changes in tanzânia guineagrass (Panicum maximum cv. Tanzânia), as realated to the supply of nitrogen rates and NO3-/NH4+ proportions in the nutrient solution. The experiment was carried out in a greenhouse, by an inert substrate and testing three nitrogen rates to supply low, intermediate and hight nitrogen nutrition and three NO3-/NH4+ proportions (100/0, 70/30, 40/60) to have no ammonium up to relative excess ammonium. Plants had shoots harvested two times and roots were collected after the second harvest. Plant evaluations included number of leaves and tillers, leaf and tiller appearance rates, leaf area, shoots and roots dry matter production, plant tissue concentrations of total nitrogen, nitrate and ammonium, SPAD value, concentrations of malondialdehyde and hydrogen peroxide, and activities of the enzymes nitrate reductase, glutamine synthase, catalase, superoxide dismutase and glutatione reductase. Low nitrogen dose damaged the leaf area and dry matter production in both growths of tanzânia grass. The excess of ammonium in the nutrient solution was also responsible for leaf area and lower mass of shoots and roots. High concentration of MDA and peroxide were found in the shoot components of grown plants under nitrogen levels ratio of NO3-/NH4+ 40/60, indicating oxidative stress in these plants. The stress caused by the exclusive supply of the ammonium nitrate form, or excess of ammonium resulted in the induction of a new band of SOD on the root system of the tanzânia guineagrass, suggesting that this enzyme has been more responsive in the elimination of ROS in the root system.

Saccharomyces cerevisiae teve seu seqüenciamento genômico finalizado em 1996, sendo composto de cerca de 6600 ORF\'s ( \"open reading frames\", quadros abertos de leitura) das quais aproximadamente 20% estão anotadas como não caracterizadas e de função molecular desconhecida. Com o objetivo de caracterizar algumas dessas ORF\'s relacionadas aos processos antioxidantes, escolhemos a proteína Yjl077cp. Através de nossos experimentos foi possível relacionar a proteína Yjl077cp com a resposta antioxidante, pois a linhagem mutante para o gene YJL077C apresentou letalidade quando exposta por 24 horas a uma concentração de 3mM de peróxido de hidrogênio (H2O2) . Testes de tolerância ao cobre, demonstraram que esse metal na concentração de 10mM, adicionado diretamente ao meio de cultura YPD, após um período de 4 horas de incubação afeta a cinética de crescimento, e após 24 horas de incubação, essa concentração é letal para a linhagem mutante. Observamos que a adição de CuSO4, causa modificação de pH do meio de cultura YPD, foram realizados experimentos para que verificássemos o efeito da acidificação do meio de cultura na viabilidade de Δics3, através de experimentos de tolerância em meio YPD ácido (pH 4.0) e com pH corrigido com adição de CuSO4. De acordo com os resultados obtidos, o efeito da letalidade de 10 mM de CuSO4 observado sem correção de pH, não ocorre quando em meio de cultura com o pH corrigido (pH6.0), demonstrando que, a letalidade da linhagem Δics3 é causada pelo acréscimo do metal e a mudança de pH (ácido, pH4.0). Testes de ICP-AES detectaram uma maior absorção intracelular de cobre na linhagem mutante Δics3, em condições de pH 4.0, quando comparada a absorção desse mesmo metal em condições de pH 6.0, demonstrando que grandes quantidades de cobre, estão sendo incorporadas para o meio intracelular, devido a acidificação do meio, sugerindo o envolvimento de Δics3, às ações das VATP-ases. Em conjunto esses resultados demonstram que o gene ICS3 é importante para a manutenção da viabilidade celular de S. cerevisiae crescida em meio de cultura com pH ácido e em condições de altas concentrações de CuSO4. O objetivo do presente trabalho foi entender a relação de ICS3 na resposta antioxidante e sensibilidade ao cobre através de experimentos de tolerância e em meio YPD ácido (pH 4.5) e com pH corrigido após adição de CuSO4. / Saccharomyces cerevisiae had its genome sequencing completed in 1996, consisting of about 6600 ORF\'s (\"open reading frames\" open reading frames) of which approximately 20% are annotated as uncharacterized and unknown molecular function. In order to characterize some of these ORF\'s related to antioxidants processes, we chose Yjl077cp protein . Through our experiments it was possible to relate the Yjl077cp protein with the antioxidant response, because the mutant strain to YJL077C gene showed lethality when exposed for 24 hours at a concentration of 3 mM hydrogen peroxide (H2O2). Copper tolerance tests demonstrated that this metal at concentration 10mM added directly to the medium YPD culture after a 4-hour period of incubation affects the growth kinetics, and after 24 hours of incubation, these concentration is lethal to mutant strain. We found that the addition of CuSO4, causes pH modification in the YPD culture medium, experiments were conducted to we check the effect of acidification of the culture medium on the viability of Δics3 through experiments of acid tolerance in YPD medium (pH 4.0) and pH adjusted with addition of CuSO4. According to the results, the effect of mortality of 10 mM CuSO4 observed without pH correction, does not occur when the culture medium with the Ph adjusted (pH6.0), demonstrating that the lethality of the strain Δics3 is caused by adding the metal and the change of pH (acid, pH4.0). ICP-OES tests detected greater intracellular uptake of copper in the mutant strain l1ics3 under conditions of pH 4.0 when compared to absorption of the same metal under conditions of pH 6.0, demonstrating that large amounts of copper, are being incorporated into the intracellular medium due to acidification of the medium, suggesting the involvement of Δics3 to the actions of the VATP-ases. Together, these results demonstrate that ICS3 gene is important for maintaining cell viability of S. cerevisiae grown in culture medium at acidic pH, and under conditions of high concentrations of CuSO4. The objective of this study was to understand the relationship ICS3 in antioxidant response and sensitivity to copper through experiments tolerance and YPD medium acid (pH 4.5) and fixed pH after addition of CuSO4.

Law, Sau Kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 111-117). / Abstract also in Chinese. / Thesis Committee --- p.i / Acknowledgements --- p.ii / Contents --- p.iii / Abstract --- p.vii / 論文摘要 --- p.x / Abbreviations --- p.xi / List of Figures --- p.xiii / List of Tables --- p.xxiii / Chapter CHAPTER ONE --- INTRODUCTION / Chapter 1.1 --- Embryonic Stem (ES) Cells / Chapter 1.1.1 --- Characteristics of ES Cells l / Chapter 1.1.2 --- Therapeutic Potential of ES Cells --- p.3 / Chapter 1.1.3 --- Myocardial Infarction and ES cells-derived Cardiomyocytes --- p.4 / Chapter 1.1.4 --- Current Hurdles of Using ES cells-derived Cardiomyocytes for Research and Therapeutic Purposes --- p.6 / Chapter 1.2 --- Transcription Factors for Cardiac Development / Chapter 1.2.1 --- GATA-binding Protein 4 (GATA-4) --- p.8 / Chapter 1.2.2 --- Myocyte Enhancer Factor 2C (MEF2C) --- p.10 / Chapter 1.2.3 --- "NK2 Transcription Factor Related, Locus 5 (Nkx2.5)" --- p.11 / Chapter 1.2.4 --- Heart and Neural Crest Derivatives Expressed 1 /2 (HANDI/2) --- p.11 / Chapter 1.2.5 --- T-box Protein 5 (Tbx5) --- p.13 / Chapter 1.2.6 --- Serum Response Factor (SRF) --- p.14 / Chapter 1.2.7 --- Specificity Protein 1 (Spl) --- p.15 / Chapter 1.2.8 --- Activator Protein 1 (AP-1) --- p.16 / Chapter 1.3 --- Reactive Oxygen Species (ROS) / Chapter 1.3.1 --- Cellular Production of ROS --- p.18 / Chapter 1.3.2 --- Maintenance of Redox balance --- p.18 / Chapter 1.3.3 --- Redox Signaling --- p.19 / Chapter 1.4 --- Nitric Oxide (NO) and NO Signaling --- p.20 / Chapter 1.5 --- Aims of the Study --- p.22 / Chapter CHAPTER TWO --- MATERIALS AND METHODS / Chapter 2.1 --- Mouse Embryonic Fibroblast (MEF) Culture / Chapter 2.1.1 --- Derivation of MEF --- p.23 / Chapter 2.1.2 --- Maintenance of MEF Culture --- p.24 / Chapter 2.1.3 --- Irradiation of MEF --- p.25 / Chapter 2.2 --- Mouse ES Cell Culture / Chapter 2.2.1 --- Maintenance of Undifferentiated Mouse ES Cell Culture --- p.26 / Chapter 2.2.2 --- Differentiation of Mouse ES Cells --- p.26 / Chapter 2.2.3 --- Exogenous addition of hydrogen peroxide (H2O2) and NO --- p.27 / Chapter 2.3 --- ROS Localization Study / Chapter 2.3.1 --- Frozen Sectioning --- p.28 / Chapter 2.3.2 --- Confocal microscopy for ROS detection --- p.28 / Chapter 2.4 --- Intracellular ROS Measurement / Chapter 2.4.1 --- "Chemistry of 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA)" --- p.29 / Chapter 2.4.2 --- Flow Cytometry for ROS Measurement --- p.29 / Chapter 2.5 --- Gene Expression Study / Chapter 2.5.1 --- Primer Design --- p.30 / Chapter 2.5.2 --- RNA Extraction --- p.31 / Chapter 2.5.3 --- DNase Treatment --- p.32 / Chapter 2.5.4 --- Reverse Transcription --- p.32 / Chapter 2.5.5 --- Quantitative Real Time PCR --- p.33 / Chapter 2.5.6 --- Quantification of mRNA Expression --- p.34 / Chapter 2.6 --- Protein Expression Study / Chapter 2.6.1 --- Total Protein Extraction --- p.34 / Chapter 2.6.2 --- Nuclear and Cytosolic Protein Extraction --- p.35 / Chapter 2.6.3 --- Measurement of Protein Concentration --- p.36 / Chapter 2.6.4 --- De-sumoylation Assay --- p.36 / Chapter 2.6.5 --- De-phosphorylation Assay --- p.37 / Chapter 2.6.6 --- De-glycosylation Assay --- p.38 / Chapter 2.6.7 --- Western Blot --- p.39 / Chapter 2.7 --- Statistical Analysis --- p.41 / Chapter CHAPTER THREE --- RESULTS / Chapter 3.1 --- Study of Endogenous ROS / Chapter 3.1.1 --- Level and Distribution of Endogenous ROS --- p.47 / Chapter 3.1.2 --- Quantification of intracellular ROS --- p.48 / Chapter 3.2 --- Effect of Exogenous Addition of Nitric Oxide (NO) on Cardiac Differentiation / Chapter 3.2.1 --- Beating Profile of NO-treated Embryoid Bodies (EBs) --- p.50 / Chapter 3.3 --- Effect of Exogenous Addition of H2O2 on Cardiac Differentiation / Chapter 3.3.1 --- Beating Profile of H2O2-treated EBs --- p.51 / Chapter 3.3.2 --- mRNA Expression of Cardiac Structural Genes --- p.52 / Chapter 3.3.3 --- Protein Expression of Cardiac Structural Genes --- p.54 / Chapter 3.3.4 --- mRNA Expression of Cardiac Transcription Factors --- p.58 / Chapter 3.3.5 --- Protein Expression of Cardiac Transcription Factors --- p.67 / Chapter 3.3.6 --- Post-translational Modifications of Cardiac Transcription Factors --- p.74 / Chapter 3.3.7 --- Translocation of Cardiac Transcription Factors --- p.89 / Chapter CHAPTER FOUR --- DISCUSSION / Chapter 4.1 --- Changes in the Level of Endogenous ROS During Cardiac Differentiation of Mouse ES Cells --- p.96 / Chapter 4.2 --- H2O2 and NO Have Opposite Effects Towards Cardiac Differentiation --- p.97 / Chapter 4.3 --- Exogenous Addition of H2O2 Advances Differentiation of Mouse ES Cells into Cardiac Lineage --- p.99 / Chapter 4.4 --- Possible Role of H2O2 in Mediating Cardiac Differentiation of Mouse ES Cells --- p.103 / Chapter 4.5 --- Future Directions --- p.108 / Conclusions --- p.110 / References --- p.111

Yung, Lai Hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 93-115). / Abstract also in Chinese. / Declaration --- p.i / Acknowledgements --- p.ii / Abbreviations --- p.iii / Abstract in English --- p.v / Abstract in Chinese --- p.ix / Contents --- p.xi / Chapter Chapter I - --- Introduction / Chapter 1.1) --- Endothelial cells function --- p.1 / Chapter 1.2) --- Oxidative stress in the vascular wall --- p.2 / Chapter 1.2.1) --- Sources of ROS --- p.3 / Chapter 1.2.2) --- Actions of ROS --- p.3 / Chapter 1.2.2.1) --- Impaired endothelium-dependent vasodilatation --- p.3 / Chapter 1.2.2.2) --- VSMC migration --- p.4 / Chapter 1.2.2.3) --- Programmed cell death (cell apoptosis) --- p.4 / Chapter 1.3) --- Endothelial cell apoptosis --- p.7 / Chapter 1.3.1) --- Apoptosis and cardiovascular diseases --- p.7 / Chapter 1.3.2) --- Mechanisms of endothelial cells apoptosis --- p.7 / Chapter 1.3.2.1) --- What are caspases? --- p.8 / Chapter 1.3.2.2) --- Death receptor-mediated apoptosis --- p.9 / Chapter 1.3.2.3) --- Mitochondria-dependent pathway --- p.9 / Chapter 1.3.3) --- Regulations of endothelial cells apoptosis --- p.10 / Chapter 1.3.3.1) --- Oxidative stress --- p.10 / Chapter 1.3.3.2) --- Shear Stress --- p.11 / Chapter 1.3.3.3) --- Growth factors --- p.12 / Chapter 1.3.3.4) --- NO --- p.12 / Chapter 1.3.3.5) --- Inflammatory mediators --- p.13 / Chapter 1.4) --- Mitogen activated kinases signaling in apoptosis --- p.15 / Chapter 1.5) --- Bone morphogenic proteins (BMPs) --- p.17 / Chapter 1.5.1) --- BMPs functions and cardiovascular system --- p.17 / Chapter 1.5.2) --- BMPs signaling pathways --- p.18 / Chapter 1.5.2.1) --- Smad-dependent pathway --- p.18 / Chapter 1.5.2.2) --- MAPKs and SAPKs pathways --- p.19 / Chapter 1.5.2.3) --- Antagonists of BMPs signaling --- p.20 / Chapter 1.5.3) --- BMP4 and cardiovascular diseases --- p.20 / Chapter 1.6) --- "Justification, long-term significance and objectives of the present project" --- p.23 / Chapter Chapter II - --- Methods and Materials / Chapter 2.1) --- Animal handling --- p.24 / Chapter 2.2) --- Endothelial cell isolation and culture --- p.24 / Chapter 2.2.1) --- Primary culture of rat endothelial cells --- p.24 / Chapter 2.2.2) --- Culture of human umbilical cord vein endothelial cells… --- p.25 / Chapter 2.3) --- Apoptosis assessment --- p.25 / Chapter 2.3.1) --- Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay --- p.25 / Chapter 2.3.2) --- Cell death detection ELISA kit --- p.26 / Chapter 2.3.3) --- Flow cytometry --- p.27 / Chapter 2.4) --- Western blot analysis --- p.28 / Chapter 2.4.1) --- Sample preparation --- p.28 / Chapter 2.4.2) --- SDS-PAGE and transfer --- p.28 / Chapter 2.5) --- DHE fluorescence --- p.29 / Chapter 2.6) --- "Drugs, chemicals and other reagents" --- p.30 / Chapter 2.6.1) --- Drugs and chemicals used in the present experiments --- p.30 / Chapter 2.6.2) --- Reagents for Western blot analysis --- p.30 / Chapter 2.6.3) --- Primary antibodies --- p.33 / Chapter 2.7) --- Small interfering RNA experiment --- p.34 / Chapter 2.8) --- Statistical analysis --- p.34 / Chapter Chapter III - --- BMP4 induces endothelial cell apoptosis in ROS related p38 MAPK and JNK mediated caspase-3 dependent pathway / Chapter 3.1) --- Introduction --- p.35 / Chapter 3.2) --- Methods and materials --- p.39 / Chapter 3.2.1) --- Isolation and culture of endothelial cells --- p.39 / Chapter 3.2.2) --- Drugs treatment --- p.39 / Chapter 3.2.3) --- Assay for cell apoptosis --- p.40 / Chapter 3.2.3.1) --- Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay --- p.40 / Chapter 3.2.3.2) --- Cell death detection ELISA kit --- p.41 / Chapter 3.2.3.3) --- Flow cytometric analysis --- p.41 / Chapter 3.2.4) --- Western blot analysis --- p.41 / Chapter 3.2.5) --- Dihydroethidium (DHE) staining --- p.42 / Chapter 3.2.6) --- Statistical analysis --- p.42 / Chapter 3.3) --- Results --- p.43 / Chapter 3.3.1) --- Dose- and time-dependent effect of BMP4 --- p.43 / Chapter 3.3.2) --- Role of caspases in apoptosis of RAECs and HUVECs --- p.43 / Chapter 3.3.3) --- Roles of BMP4 and ROS in endothelial cell apoptosis --- p.44 / Chapter 3.3.3.1) --- Noggin antagonism of BMP4-induced effect --- p.44 / Chapter 3.3.3.2) --- NAD(P)H oxidase-mediated ROS production --- p.44 / Chapter 3.3.3.3) --- Inhibition of endothelial cell apoptosis by ROS scavengers --- p.45 / Chapter 3.3.4) --- Roles of MAPKs/SAPKs in BMP4-induced endothelial cell apoptosis --- p.45 / Chapter 3.3.5) --- Relationship between ROS and MAPKs/SAPKs --- p.46 / Chapter 3.3.6) --- Relationship between p38 MAPK and JNK --- p.46 / Chapter 3.4) --- Discussion --- p.82 / Chapter 3.4.1) --- Caspase-dependent pathways --- p.82 / Chapter 3.4.2) --- Oxidative stress --- p.85 / Chapter 3.4.3) --- Role of MAPKs activation in BMP4-induced endothelial cell apoptosis --- p.87 / Chapter 3.4.4) --- ROS mediates BMP4-induced activation of MAPKs --- p.88 / Chapter 3.4.5) --- Role of p38 MAPK in the activation of JNK 1 --- p.89 / Chapter 3.5) --- Concluding remarks --- p.91 / References --- p.93 / Publications and Awards --- p.116

胰臟內分泌細胞分化的調控事件的研究揭示了胰島素分泌細胞的形成。這一原理既有利於體外誘導用於移植的胰島素分泌細胞，又可應用于糖尿病病人自體胰島素分泌細胞的再生。正在發育的組織和器官中，發現了腎素血管緊張素（RAS）成員，揭示了他們在發育過程中的潛在調控作用。另外，對 RAS 信號系統做出應答的活性氧化物質（ROS），被認為是第二信使，通過對轉錄調控因子的氧化還原的修飾促進分化。作為 ROS 的主要來源，NADPH 已被證實在各類細胞和組織中參與了祖細胞的分化。儘管如此，依賴於 NADPH 氧化酶的 ROS對于胰腺內分泌細胞分化的調控作用仍不清楚。基於這個背景，本研究致力於揭示 RAS 和 NADPH 氧化酶依賴性 ROS 在胰腺內分泌細胞分化中的作用。本實驗將在小鼠胰臟原基培養物和尿鏈黴素（STZ）誘導的新生大鼠上進行。 結果顯示，經典 RAS 成員中的血管緊張素 2 型受體（AT₂R）分佈於內分泌祖細胞的細胞核，之後穿梭定位於胰島素分泌細胞的細胞質。阻斷 AT₂R 功能抑制了Ngn3，胰島素的表達以及 β 細胞的增值。在不同的胚胎期 ROS 的水平發生了改變。對于培養的胰臟原基施加適當的外源 ROS，刺激了內分泌細胞的分化。同時，ROS 清除劑減弱了胰島細胞分化和成熟的標記基因的表達。NOX4 以及其相關的亞基 p22phox 是 NADPH 氧化酶成員，其在胰臟發育過程中的變化同 ROS 水平的變化相似，並且持續表達與內分泌細胞系統。在 NGN3 高表達的胚胎期15.5 天，它們定位于表達 NGN3 的細胞；在 NGN3 表達下調，且胰島素表達升高的胚胎期 17.5 天，它們分佈於胰島素表達細胞。而且，NADPH 氧化酶的抑製劑 DPI 削弱了胰臟培養物中的內分泌祖細胞的分化, 外源 H₂O₂ 的加入扭轉了這一現象。 / 另一方面，在 STZ 誘導的新生大鼠的研究中，DPI 負調節 β 細胞的再生。血糖失調，胰島結構毀壞以及血清胰島素匱乏的現象發生在了 DPI 處理組。另外，DPI 減弱了 NGN3 的表達而並非 Ki67, 顯示 β 細胞的分化而並非增值對於 ROS 的刺激進行了應答。在體內和體外的實驗中，DPI 也抑制了 NGN3 的轉綠調控因子 SOX9 在胰腺祖細胞中的表達。有趣的是，過表達 SOX9 可以恢復 DPI 引發的對於 NGN3 的抑制 。結合以上數據，本研究顯示 NADPH 氧化酶依賴性ROS 誘導的信號通路參與了胰腺祖細胞到胰島素分泌細胞的分化。 / Investigations into the regulatory events that modulate pancreatic endocrine cell differentiation shed light on the generation of sufficient insulin-producing cells in vitro for transplantation or regeneration of β cells in patients with diabetes. The expression of renin-angiotensin system (RAS) components has been detected in development tissue and organs, implicating their regulatory role in developmental processes. On the other hand, reactive oxygen species (ROS) are responsive to RAS signaling pathways and act as second messengers to promote differentiation through redox modification of transcriptional factors essential for differentiation. As a major source of ROS, NADPH oxidase has been shown to participate in the progenitor differentiation in a variety of cells and tissues. Despite this finding, the role of NADPH oxidase-dependent ROS in regulating pancreatic endocrine cell differentiation remains ambiguous. Against this background, the study was aimed at elucidating the roles of RAS components and NADPH oxidase-derived ROS during differentiation of pancreatic endocrine cells using mouse pancreatic rudiments and streptozotocin-treated neonatal rats. / Results showed that angiotensin II type 2 receptor (AT₂R), a major component of the classical RAS, was localized within the nuclei of endocrine progenitors in the cultured pancreatic rudiments; following the differentiation of endocrine progenitors into insulin producing cells, it translocated to cytoplasm. Blockade of AT₂R impeded the expression of Ngn3 and insulin as well as proliferation of β-cells. In addition, the dynamic changes of ROS levels were found in mouse pancreata at different embryonic days, concomitant with induction of endocrine cell differentiation induced by modest exogenous ROS in pancreatic rudiment cultures. Moreover, scavenger of ROS diminished the expression of islet cell markers for differentiation and maturation. NOX4 and its associated subunit p22phox, which are the member of NADPH oxidase, exhibited similar changes of expression to that of ROS levels during pancreas development and persisted in the endocrine lineage; they were located in NGN3⁺ cells at E15.5 during the burst of NGN3 expression and then distributed in insulin⁺ cell at E17.5, the latter being the phase that has a decline in NGN3 expression with an increase of insulin. Furthermore, administration of NADPH oxidase inhibitor, diphenylene iodonium (DPI) attenuated the differentiation of endocrine progenitors in rudiment cultures, while exogenous ROS reversed this effect. / On the other hand, studies performed in streptozotocin-induced neonatal rats showed that β cell regeneration was negatively affected by DPI treatments; consistently, impaired blood glucose control, disturbed islet architecture and deficient serum insulin were observed in DPI-treated groups. In addition, DPI treatments blunted NGN3 expression, but not Ki67-labeling beta-cells, suggesting that differentiation beyond proliferation of β-cells was accountable in response to ROS stimulation. Administration of DPI also suppressed the levels of SOX9, a transcriptional regulator of NGN3, in pancreatic progenitor cells, as evidenced by both in vivo and in vitro studies. Interestingly, over-expression of SOX9 could restore the repression of NGN3 induced by DPI. Taken all these data together, our results indicate that NADPH oxidase-dependent ROS-induced signaling pathway is involved in the differentiation of pancreatic endocrine progenitors into insulin-producing β cells. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liang, Juan. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 171-205). / Abstracts also in Chinese.