A diversidade de organismos oriundos do ambiente marinho constitui uma fonte significativa de substâncias estruturalmente inéditas e biologicamente ativas, dentre as quais, diversas inspiraram o desenvolvimento de novas classes de agentes terapêuticos. Neste contexto, macroalgas vermelhas do gênero Bostrychia (Rhodomelaceae) foram coletadas em praias do litoral norte do estado de São Paulo e têm sido objeto de estudos químicos e biológicos, no Laboratório de Química Orgânica do Ambiente Marinho (LQOAM - NPPNS) da FCFRPUSP, sob a supervisão da Profa. Dra. Hosana M. Debonsi. As algas da espécie Bostrychia radicans demonstraram potencial quando avaliadas as atividade citotóxica, tripanocida, leishmanicida e antimicrobiana; além de um perfil químico interessante, evidenciado pelo isolamento de substâncias inéditas na literatura. Neste contexto, o presente trabalho descreve a continuidade do estudo químico da espécie B. radicans, coletada no Manguezal do Rio Escuro, em Ubatuba-SP; bem como o potencial biológico desta espécie, além da avaliação da atividade de enzimas fenolsulfatases na espécie. Ainda, no sentido de explorar novas fontes promissoras para o isolamento de substâncias bioativas, este trabalho descreve o isolamento de micro-organismos endofíticos associados à espécie B. radicans. Foram isoladas 45 linhagens de micro-organismos; dentre as quais foram selecionadas nove linhagens para obtenção de extratos e realização de triagens química e biológica. A partir desta triagem inicial, foi realizado o estudo químico dos fungos Xylaria sp., Penicillium brevicompactum e Phomopsis longicolla. A partir da Xylaria sp. foram isoladas as seguintes substâncias: ácido 2,5-diidroxibenzóico, 8-diidroxinaftol 1-O-a-glucopiranosídeo, 8-metóxi-3-metil-1- isocromanona e ácido pilifórmico. O estudo químico de Penicillium brevicompactum resultou no isolamento das substâncias: ácido micofenólico, asperfenamato, brevianamida A, brevianamida C e brevianamida oxindol, substância inédita como produto natural. A partir de Phomopsis longicolla foi isolado o dicerandrol C. Este trabalho descreve ainda o potencial biológico de algumas destas substâncias isoladas. O estudo químico e biológico de microorganismos realizado no LQOAM estimulou a consolidação de uma colaboração com o Prof. Dr. Isidro C. Gonzalez, através da realização de um estágio de 12 meses no Laboratório Botrytis (Departamento de Química Orgânica, Universidade de Cádiz). Durante este período foi realizado o estudo químico do fitopatógeno Botrytis cinerea, visando o isolamento de novos metabólitos ou toxinas; além do estudo da biogênese destas substâncias, através de ensaios utilizando precursores isotopicamente marcados. / The diversity of organisms from the marine environment is a significant source of structurally novel and biologically active substances, several of which have inspired the development of new classes of therapeutic agents. In this context, red macroalgae belonging to Bostrychia genus (Rhodomelaceae) were collected on beaches of the north coast of São Paulo State and have been studied chemically and biologically in the Laboratory of Organic Chemistry of the Marine Environment - (LQOAM - NPPNS) at FCFRP-USP, under Prof. Hosana M. Debonsi supervision. Algae Bostrychia radicans species showed cytotoxic, trypanocidal, antileishmanial and antimicrobial potential, besides a interesting chemical profile, evidenced by the isolation of new compounds in the literature. In this context, this work describes the sequential chemical study of B. radicans species, collected at the Rio Escuro Mangrove, Ubatuba-SP, as well as the biological potential of this species. Also, the phenolsulphatases enzyme activity was evaluated in this species. Still, in order to explore new promising sources for the isolation of bioactive substances, this study describes the isolation of endophytic microorganisms associated to B. radicans. In this way, 45 strains of microorganisms were isolated and nine strains were selected for extracts preparation; and subsequently chemical and biological screenings. Based on the biological screening and chemical profile analyses, the large-scale fermentation of the endophytic fungi Xylaria sp., Penicillium brevicompactum and Phomopsis longicolla was carried out. The chromatographic purification of the bioactive acethyl acetate extract from Xylaria sp. allowed the isolation of 2,5-dihydroxybenzoic acid, 8- dihydroxynaphtol 1-O-a-glucopyranoside, 8-methoxy-3-methyl-1-isochromanone and piliformic acid. Chemical studies of Penicillium brevicompactum resulted in the isolation of: mycophenolic acid, asperphenamate, brevianamide A, brevianamide C and brevianamide oxindole, isolated for the first time as a natural product. From Phomopsis longicolla was isolated dicerandrol C. This thesis also describes the potential biological of some of these isolated compounds. The chemical and biological studies of microorganisms achieved in LQOAM encouraged the consolidation of a collaboration work with Prof. Dr. Isidro C. Gonzalez, through the completion of a 12-month internship at the Laboratory Botrytis (Department of Organic Chemistry, University of Cádiz). During this period, was conducted the chemical study of plant pathogen Botrytis cinerea, aiming the isolation of new metabolites or toxins, in addition to studying the biogenesis of these substances, through experiments using isotopically labeled precursors.

A diversidade de organismos oriundos do ambiente marinho constitui uma fonte significativa de substâncias estruturalmente inéditas e biologicamente ativas, dentre as quais, diversas inspiraram o desenvolvimento de novas classes de agentes terapêuticos. Neste contexto, macroalgas vermelhas do gênero Bostrychia (Rhodomelaceae) foram coletadas em praias do litoral norte do estado de São Paulo e têm sido objeto de estudos químicos e biológicos, no Laboratório de Química Orgânica do Ambiente Marinho (LQOAM - NPPNS) da FCFRPUSP, sob a supervisão da Profa. Dra. Hosana M. Debonsi. As algas da espécie Bostrychia radicans demonstraram potencial quando avaliadas as atividade citotóxica, tripanocida, leishmanicida e antimicrobiana; além de um perfil químico interessante, evidenciado pelo isolamento de substâncias inéditas na literatura. Neste contexto, o presente trabalho descreve a continuidade do estudo químico da espécie B. radicans, coletada no Manguezal do Rio Escuro, em Ubatuba-SP; bem como o potencial biológico desta espécie, além da avaliação da atividade de enzimas fenolsulfatases na espécie. Ainda, no sentido de explorar novas fontes promissoras para o isolamento de substâncias bioativas, este trabalho descreve o isolamento de micro-organismos endofíticos associados à espécie B. radicans. Foram isoladas 45 linhagens de micro-organismos; dentre as quais foram selecionadas nove linhagens para obtenção de extratos e realização de triagens química e biológica. A partir desta triagem inicial, foi realizado o estudo químico dos fungos Xylaria sp., Penicillium brevicompactum e Phomopsis longicolla. A partir da Xylaria sp. foram isoladas as seguintes substâncias: ácido 2,5-diidroxibenzóico, 8-diidroxinaftol 1-O-a-glucopiranosídeo, 8-metóxi-3-metil-1- isocromanona e ácido pilifórmico. O estudo químico de Penicillium brevicompactum resultou no isolamento das substâncias: ácido micofenólico, asperfenamato, brevianamida A, brevianamida C e brevianamida oxindol, substância inédita como produto natural. A partir de Phomopsis longicolla foi isolado o dicerandrol C. Este trabalho descreve ainda o potencial biológico de algumas destas substâncias isoladas. O estudo químico e biológico de microorganismos realizado no LQOAM estimulou a consolidação de uma colaboração com o Prof. Dr. Isidro C. Gonzalez, através da realização de um estágio de 12 meses no Laboratório Botrytis (Departamento de Química Orgânica, Universidade de Cádiz). Durante este período foi realizado o estudo químico do fitopatógeno Botrytis cinerea, visando o isolamento de novos metabólitos ou toxinas; além do estudo da biogênese destas substâncias, através de ensaios utilizando precursores isotopicamente marcados. / The diversity of organisms from the marine environment is a significant source of structurally novel and biologically active substances, several of which have inspired the development of new classes of therapeutic agents. In this context, red macroalgae belonging to Bostrychia genus (Rhodomelaceae) were collected on beaches of the north coast of São Paulo State and have been studied chemically and biologically in the Laboratory of Organic Chemistry of the Marine Environment - (LQOAM - NPPNS) at FCFRP-USP, under Prof. Hosana M. Debonsi supervision. Algae Bostrychia radicans species showed cytotoxic, trypanocidal, antileishmanial and antimicrobial potential, besides a interesting chemical profile, evidenced by the isolation of new compounds in the literature. In this context, this work describes the sequential chemical study of B. radicans species, collected at the Rio Escuro Mangrove, Ubatuba-SP, as well as the biological potential of this species. Also, the phenolsulphatases enzyme activity was evaluated in this species. Still, in order to explore new promising sources for the isolation of bioactive substances, this study describes the isolation of endophytic microorganisms associated to B. radicans. In this way, 45 strains of microorganisms were isolated and nine strains were selected for extracts preparation; and subsequently chemical and biological screenings. Based on the biological screening and chemical profile analyses, the large-scale fermentation of the endophytic fungi Xylaria sp., Penicillium brevicompactum and Phomopsis longicolla was carried out. The chromatographic purification of the bioactive acethyl acetate extract from Xylaria sp. allowed the isolation of 2,5-dihydroxybenzoic acid, 8- dihydroxynaphtol 1-O-a-glucopyranoside, 8-methoxy-3-methyl-1-isochromanone and piliformic acid. Chemical studies of Penicillium brevicompactum resulted in the isolation of: mycophenolic acid, asperphenamate, brevianamide A, brevianamide C and brevianamide oxindole, isolated for the first time as a natural product. From Phomopsis longicolla was isolated dicerandrol C. This thesis also describes the potential biological of some of these isolated compounds. The chemical and biological studies of microorganisms achieved in LQOAM encouraged the consolidation of a collaboration work with Prof. Dr. Isidro C. Gonzalez, through the completion of a 12-month internship at the Laboratory Botrytis (Department of Organic Chemistry, University of Cádiz). During this period, was conducted the chemical study of plant pathogen Botrytis cinerea, aiming the isolation of new metabolites or toxins, in addition to studying the biogenesis of these substances, through experiments using isotopically labeled precursors.

Le modèle biogéochimique de résolution complexe MIRO a été développé pour étudier la dynamique des efflorescences de Phaeocystis en zone côtière belge (BCZ) en réponse aux apports de nutriments anthropiques délivrés directement par l’Escaut et indirectement par la Seine via les eaux atlantiques entrantes. Le modèle MIRO décrit les cycles du carbone (C), de l’azote (N), du phosphore (P) et de la silice (Si) au travers de 38 compartiments chimiques, planctoniques et benthiques clés de l’écosystème côtier dominé par Phaeocystis. Il a été validé dans une configuration multi boite simple en utilisant des forçages climatologiques pour la période 1989-1999 et sur base d’une comparaison visuelle des simulations de nutriments et des variables planctoniques avec les données récoltées durant cette même période.<p>Le modèle validé a ensuite été utilisé pour étudier le fonctionnement de l’écosystème et les cycles biogéochimiques associés. Plus précisément, les bilans de carbone et de nutriments réalisés sur base des flux biologiques modélisés ont montré que l’écosystème de la BCZ, dominé par les efflorescences de Phaeocystis, se caractérise par une faible efficience trophique, une faible capacité de rétention/élimination des apports de nutriments d’origine anthropique et une faible capacité d’absorption du CO2 atmosphérique. Des scénarios annulant tour à tour l’activité biologique et les apports de carbone par les rivières ont permis de déterminer les rôles respectifs de la température, des processus biologiques et des apports de nutriments et de carbone par les rivières dans l’évolution saisonnière de la pCO2 des eaux de surface.<p>L’effet combiné des apports anthropiques de nutriments et des conditions météorologiques locales (débit, vent, température) a été étudié sur base d’une simulation effectuée pour la période contemporaine (1989-2003) en utilisant les forçages réels mesurés. La comparaison visuelle des simulations et des observations montre que, si le modèle est parfaitement capable de reproduire les successions phytoplanctoniques, il est par contre moins performant en ce qui concerne la reproduction des signaux extrêmes. Il apparaît donc que l’échelle de temps (mensuelle) utilisée pour décrire la variabilité des forçages est trop longue et ne permet pas de capter les variations hydrologiques à court terme résultant du vent et de la marée. <p>De manière à mieux comprendre le lien entre les activités humaines sur le bassin versant et l’eutrophisation des zones côtières, le modèle MIRO a été couplé aux sorties du modèle de rivière RIVERSTRAHLER appliqué à la Seine et à l’Escaut sur une période de 50 ans (1950-1998). Les résultats obtenus montrent que l’importance des efflorescences de diatomées est conditionnée par les apports de PO4, alors que l’importance des Phaeocystis est directement liée à l’importance des apports de NO3. Un bilan établi pour la BCZ montre que plus de 50% des apports annuels de N et 60% des apports annuels de P proviennent des eaux Atlantiques et pointe l‘importance des apports de la Seine pour l’enrichissement de la BCZ. <p>Différents scénarios de réduction des apports de nutriments provenant des rivières ont été réalisés afin de cibler le ou les nutriments à diminuer prioritairement pour réduire les efflorescences de Phaeocystis. Les résultats montrent que, dans les conditions actuelles, seule une réduction des apports de NO3 prédit une diminution des efflorescences de Phaeocystis. De plus, pour avoir un abattement significatif de ces efflorescences, il est nécessaire d’agir de manière conjointe sur les apports de la Seine et de l’Escaut.<p>En vue de l’implémentation du code MIRO dans un modèle 3D hydrodynamique et pour tenir compte de la variabilité spatiale des sédiments dans la zone étudiée, une paramétrisation des flux de nutriments à l’interface eau-sédiment a été recherchée sur base des résultats obtenus avec un modèle diagénétique analytique décrivant la dégradation de la matière organique et les cycles de l’azote et du phosphore dans les sédiments. <p> / Doctorat en sciences, Spécialisation biologie animale / info:eu-repo/semantics/nonPublished

[Truncated abstract] Kelp beds of South-Western Australia have high alpha (within habitat) diversity, through high species turnover at small spatial scales. The E. radiata canopy has a strong negative influence on the diversity of the understorey through intense interspecific competition for light. Literature suggests that when the competitively dominant species such as E. radiata are physically removed, diversity will increase, as less competitive species become more abundant. Apart from disturbance, evidence suggests that reef topography at the 1-10 m vertical scale also has an influence on the structure of the kelp beds, particularly in reference to relative abundance of canopy algae and species richness of the assemblage. In this thesis, I explore the role of algal assemblage recovery from physical disturbance to maintain high diversity. I also investigate the influence of reef structure (in terms of topography at the 1-10 m vertical scale) on assemblage recovery. This thesis provides a valuable functional explanation for the high diversity observed in South-Western algal assemblages. In addition, it explores the influence of reef topography which has received little attention to date . . . Overall, this thesis argues that the high alpha diversity in algal assemblages of South-Western Australia is due to local scale processes including disturbance and assemblage recovery which generate diversity by the creation of species rich gap states and by phase-shifts during the recovery process, creating a mosaic of different patch types. Assemblage recovery is composed of several processes, including survival of juvenile kelp sporophytes and canopy shading, added to macroalgal diversity through spatial and temporal variation in their outcomes. Reef topography contributed to algal diversity by influencing the processes associated with assemblage recovery through alteration of key physical variables including light levels and water motion.

No description available.