Pharmacodynamic studies are important for the optimal use of antimicrobial agents. Combination antifungal therapy may be one method to improve outcome in invasive Candida infections. An in vitro kinetic model to study the pharmacodynamic effects of a combination of two antifungal agents with different elimination rates was developed and the pharmacodynamics of amphotericin B (AMB), voriconazole (VRC) or the combination was evaluated. Exposure to VRC inhibited the fungicidal activity of sequential doses of AMB against VRC-susceptible strains of C. albicans. The interaction was VRC dose-dependent. AMB activity was regained once VRC was removed or it increased gradually when the concentration of VRC had fallen below the minimum inhibitory concentration (MIC). The VRC-AMB interaction, however, was also present against strains of C. albicans, C. glabrata and C. krusei despite reduced VRC susceptibility. Against these strains the interaction was not predicted by the MIC value, suggesting that mechanisms of resistance may be of importance. Until more data are available, a reasonable recommendation is probably to avoid the sequential use of VRC followed by AMB and to use the combination of VRC and AMB for the treatment of Candida infections with caution. Only the unbound fraction of a drug is generally accepted as pharmacologically active. The activity of posaconazole (POS) with a protein binding of 98-99% was tested in serum against Candida species and compared with the calculated unbound serum concentration in protein-free media. Significant differences emerged at clinically relevant POS serum concentrations of 1.0 and 0.10 mg/l compared with the serum control regimen against one strain of C. lusitaniae. In RPMI 1640 the corresponding calculated unbound concentrations resulted in no effect for the low dose regimen compared with the RPMI 1640 control regimen. Further, against seven additional Candida strains tested, the effect of POS was greater in serum than in RPMI 1640. A flux from serum protein bound to fungal lanosterol 14α-demethylase bound POS may be the explanatory mechanism.

Mirtazapine is an atypical antidepressant employed clinically for the treatment of major depression. As a multipotent antagonist it acts at α2a-adrenergic receptors (α2a -ARs). serotonin type-2A receptors (5-HT2a-Rs) and histamine type-I receptors (H1-Rs). Its actions at the α2a-AR have been proposed to play a role in its putative earlier onset of action. However, it is not known whether mirtazapine is a neutral antagonist or inverse agonist at α2a- ARs. The current study aimed to determine the mode of α2a-AR antagonism by mirtazapine, as well as to investigate in vitro the modulatory effects of mirtazapine pre-treatments on β-adrenergic receptor (β-AR), muscarinic acetylcholine receptor (mAChR) and α2a-AR functions. Chinese hamster ovary (CHO-K1) cells expressing the porcine α2a-AR at high numbers (α2a-H), a constitutively active mutant α2a-AR (α2a--CAM), or mock-transfected control cells (neo) were radio-labelled with [3H]-adenine and concentration-effect curves of mirtazapine, yohimbine, mianserin or idazoxan were constructed, measuring [3H]-cAMP accumulation. In addition human neuroblastoma SH-SY5Y cells and CHO-K1 cells expressing the porcine α2a- AR at low numbers (am-L) were used to investigate the effect of mirtazapine pre-treatments on mAChRs and β-ARS or α2a-ARs respectively. After radio-labelling with myo-[2-3H]-inositol or [2-%]-adenine, radio-label uptake was measured and receptor function was investigated by constructing concentration-effect curves, measuring [3H]-IPx or [3H]-cAMP accumulation respectively. The results from the current study show that mirtazapine binds to the α2a-AR with an affinity value in the lower micromolar range (K1≈ 0.32 µM; pK1 = 6.50 ± 0.07). Mirtazapine is not a partial agonist at α2a-ARs as it does not affect [3H]-cAMP accumulation in α2a-H cells. Preliminary results suggest that mirtazapine displays partial inverse agonism in α2a-CAM cells, while mianserin displays neutral antagonism. Mirtazapine pre-treatment in SH-SY5Y cells does not alter muscarinic receptor function (different from fluoxetine and imipramine), but reduces I-isoproterenol-induced increase in [3H]-cAMP accumulation in SH-SY5Y cells (typically associated with chronic antidepressant activity). Although inconclusive, the data also suggests that mirtazapine may reduce α2a-AR function. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2005.

Mirtazapine is an atypical antidepressant employed clinically for the treatment of major depression. As a multipotent antagonist it acts at α2a-adrenergic receptors (α2a -ARs). serotonin type-2A receptors (5-HT2a-Rs) and histamine type-I receptors (H1-Rs). Its actions at the α2a-AR have been proposed to play a role in its putative earlier onset of action. However, it is not known whether mirtazapine is a neutral antagonist or inverse agonist at α2a- ARs. The current study aimed to determine the mode of α2a-AR antagonism by mirtazapine, as well as to investigate in vitro the modulatory effects of mirtazapine pre-treatments on β-adrenergic receptor (β-AR), muscarinic acetylcholine receptor (mAChR) and α2a-AR functions. Chinese hamster ovary (CHO-K1) cells expressing the porcine α2a-AR at high numbers (α2a-H), a constitutively active mutant α2a-AR (α2a--CAM), or mock-transfected control cells (neo) were radio-labelled with [3H]-adenine and concentration-effect curves of mirtazapine, yohimbine, mianserin or idazoxan were constructed, measuring [3H]-cAMP accumulation. In addition human neuroblastoma SH-SY5Y cells and CHO-K1 cells expressing the porcine α2a- AR at low numbers (am-L) were used to investigate the effect of mirtazapine pre-treatments on mAChRs and β-ARS or α2a-ARs respectively. After radio-labelling with myo-[2-3H]-inositol or [2-%]-adenine, radio-label uptake was measured and receptor function was investigated by constructing concentration-effect curves, measuring [3H]-IPx or [3H]-cAMP accumulation respectively. The results from the current study show that mirtazapine binds to the α2a-AR with an affinity value in the lower micromolar range (K1≈ 0.32 µM; pK1 = 6.50 ± 0.07). Mirtazapine is not a partial agonist at α2a-ARs as it does not affect [3H]-cAMP accumulation in α2a-H cells. Preliminary results suggest that mirtazapine displays partial inverse agonism in α2a-CAM cells, while mianserin displays neutral antagonism. Mirtazapine pre-treatment in SH-SY5Y cells does not alter muscarinic receptor function (different from fluoxetine and imipramine), but reduces I-isoproterenol-induced increase in [3H]-cAMP accumulation in SH-SY5Y cells (typically associated with chronic antidepressant activity). Although inconclusive, the data also suggests that mirtazapine may reduce α2a-AR function. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2005.

The cultivation of flowers is, in Brazil, very recent and little known species have a high ornamental potential, Cartamus is such a species and there are cultivars for the production of oil and as well as for ornamental pourposes. Being a recent crop in Brazil, little is known about its associated diseases, specially those that affect the seeds and the soil borne, such as white mold that causes great losses to several crops. Six experiments were conducted with the objectives of testing the reaction of the crop to isolates of Sclerotinia sclerotiorum, the biocontrol of S. sclerotiorum and of pathogens associated to the seeds, and the effect of the biocontrollers on cartamus plant growth. Isolates of the pathogen from chrisantemum, lettuce, soybean, and carrots, as well as isolates of Trichoderma sp. (ETSR 20 e TC 1.15) and comercial products of Trichoderma spp. (Agrotrich and Trichodel®) were used. In the reaction test, the cartamus crop was more severely attacked by the isolate obtained from lettuce, which when incorporated to commercial substrate did not promote the development of the disease in plant, but reduced plant growth. Trichodel® was the product that promoted the highest growth of plants when incorporated to the substrate, even in the absence of the pathogen. The product more efficient in controlling seed pathogens was Agrotrich. In the growth of seedlings, the isolates ETSR20 and TC1.15 were the best, when applied to the seeds and the latter promoted the best emergency of seeds in commercial substrate. Therefore, the Trichoderma based products can be used in the control of seed pathogens and growth promotion of cartamus plants as seed or substrate treatment. There are differences in disease severity on cartamus among isolates of S. sclerotiorum from different crops and its presence reduces the crop s growth, even in the absence of visible symptoms / A floricultura, no Brasil, é relativamente recente, existindo espécies pouco conhecidas com alto potencial ornamental. O cártamo é uma delas e possui cultivares tanto para a produção de óleo quanto para ornamentação. Por ser uma cultura recente no Brasil, pouco se conhece sobre as doenças associadas a ela, especialmente as que afetam as sementes e as veiculadas pelo solo, como o mofo branco, que causa grandes prejuízos a diversas culturas. Seis experimentos foram conduzidos com o objetivo de testar a reação da cultura a isolados de Sclerotinia sclerotiorum, o biocontrole de patógenos associados às sementes e de Sclerotinia sclerotiorum e o efeito dos biocontroladores no crescimento de plantas de cártamo. Foram utilizados isolados de Sclerotinia sclerotiorum das culturas do crisântemo, alface, soja e cenoura, e isolados de Trichoderma spp. (ETSR 20 e TC 1.15) e formulados comerciais à base de Trichoderma spp. (Agrotrich e Trichodel®). No teste de reação, a cultura do cártamo foi mais severamente atacada pelo isolado proveniente da alface, o qual, quando incorporado ao substrato comercial, não promoveu o desenvolvimento da doença nas plantas, porém prejudicou seu crescimento. Trichodel® foi o produto que maior crescimento proporcionou às plantas quando incorporado ao substrato, mesmo sem a presença do patógeno. O produto mais eficiente no controle dos patógenos das sementes foi o formulado comercial Agrotrich. No crescimento de plântulas, os isolados ETSR 20 e TC 1.15 se sobressaíram quando aplicados às sementes e este obteve melhor resultado na emergência de plântulas em substrato. Assim, os produtos a base de Trichoderma são viáveis para controle de patógenos de sementes e crescimento de plantas tanto no tratamento de sementes como do substrato. Existem diferenças na severidade da doença em cártamo entre isolados de Sclerotinia sclerotiorum oriundos de diferentes culturas e sua presença reduz o crescimento da cultura, mesmo na ausência de sintomas visíveis

Made available in DSpace on 2014-06-11T19:32:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-12Bitstream added on 2014-06-13T21:05:12Z : No. of bitstreams: 1 rodrigues_a_dr_rcla.pdf: 1112229 bytes, checksum: f59b4675edb860a1b20d6b5f1f7e6dc9 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As formigas da tribo Attini são conhecidas pela complexa simbiose que mantêm com fungos, os quais cultivam como alimento. É sabido que além desse fungo, outros microrganismos podem ser encontrados nos ninhos desses insetos e estudos prévios apontaram que alguns microfungos (i.e. leveduras e fungos filamentosos) podem ser importantes nessa simbiose. O objetivo do presente trabalho foi avaliar o papel desses microfungos associados aos jardins dessas formigas. Analisando várias espécies do gênero Acromyrmex do sul do Brasil, demonstrou-se que as formigas importam uma comunidade diversa de microfungos para seus ninhos, provavelmente provenientes do solo e do substrato vegetal que as formigas utilizam para cultivar seu fungo. Num segundo estudo, avaliando formigas Attini da América do Norte (Atta texana, Trachymyrmex septentrionalis e Cyphomyrmex wheeleri) observou-se que a estrutura das comunidades de microfungos nos jardins desses insetos não se correlaciona com a variação sazonal, sugerindo que não existam relações espécie-específicas entre as formigas e os microfungos. Apesar de tais microrganismos não serem especialistas dos jardins desses insetos, é sugerido que os microfungos atuem como antagonistas do fungo simbionte. Ainda, descobriu-se que o parasita especializado Escovopsis spp. parece ser menos freqüente nas populações de formigas da América do Sul em relação as Attini da América Central, porém estudos adicionais são necessários para estabelecer a epidemiologia desse parasita nos ninhos das Attini. Num terceiro estudo, demonstrou-se que leveduras presentes nos jardins de fungos da formiga cortadeira A. texana inibem o crescimento de Escovopsis spp., sugerindo que esses insetos utilizam outros microrganismos, além das bactérias presentes em suas cutículas (Pseudonocardia spp.), para inibir esse parasita. Esse achado traz importantes implicações para essa... / Ants in the tribe Attini are well-known social insects that maintain a symbiotic relationship with fungi which they cultivate as food. Besides of the cultivated fungi, fungus gardens contain several other microorganisms considered to be potential players in this symbiosis. The aim of the present study was to evaluate the possible roles of microfungi (i.e. yeasts and filamentous fungi) in attine gardens. Our microbial profiling of gardens from several species in the genus Acromyrmex from South Brazil revealed that ants can harbor a diverse community of microfungi that probably originated from the surrounding soil or from the substrate used to manure the cultivated fungus. In this sense, additional studies of North American attine species (Atta texana, Trachymyrmex septentrionalis and Cyphomyrmex wheeleri) demonstrated that the structure of microfungal communities in gardens of these ants did not correlate with seasonal changes over a one year period, again suggesting there are no species-specific relationships among ants and microfungi species. Although, the microfungi are not specialized parasites of the attine ant-fungus symbiosis we suggest they can be considered antagonists to the cultivated fungus. Moreover, we demonstrated that the specialized parasite Escovopsis spp. is probably less frequent in South America than in Central America and we reinforce that additional studies are necessary to unravel the epidemiology of this parasite in attine gardens. In another study, we showed that yeasts isolated from gardens of the leafcutter ant A. texana can significantly inhibit the growth of Escovopsis sp. This interesting finding suggests that attine ants may use additional microbes to protect their gardens against Escovopsis spp. and not only actinomycete bacteria (Pseudonocardia spp.) found in their cuticles. Finally, we studied microfungi relationships with female alates (gynes) in two... (Complete abstract click electronic access below)

« Les Shipibo nous doivent un jeu !» - disent les Kakataibo en insistant sur le caractère contraignant du système d'échange de fête dans lequel ils sont engagés aujourd'hui avec leurs anciens ennemis. L'objectif de ce travail est de fournir une ethnographie du rapport antagoniste entre les deux groupes de la famille linguistique pano du bassin de l'Aguaytía, en Amazonie péruvienne. Il entend également d'offrir un nouvel aperçu sur les propositions théoriques concernant la socialité, et plus précisément l'inimitié, dans les basses terres qui dominentl'anthropologie amazoniste depuis plus de vingt ans, en les confrontant avec un matériel ethnographique récent.L'abandon des pratiques guerrières qui étaient jadis le modus operandi privilégié entre les ennemis, ainsi que l'intensification des contacts avec la société nationale et avec les Blancs ont engendré les nouvelles formes du rapport entre les groupes amérindiens. Si la figure de l'ennemi est toujours indispensable dans les constructions identitaires récentes, nous ne sommes plus ici dans la logique de la prédation ontologique. L'exemple de la fête de la communauté native est dece point de vue particulièrement parlant. Une monnaie d'échange entre les chefs de villages adverses, les différentes séquences de la fête laissent entrevoir la pluralité des formes relationnelles que les Kakataibo entretiennent avec leurs différents affins. Tandis que l'idiome sorcellaire qu'ils mobilisent pour parler du football produit l'asymétrie et la distance avec leurs affins potentielles - les Shipibo, la mise en scène d'une femme blanche, belle, intelligente et érotisée par les filles kakataibo lors du concours de beauté a pour effet, au contraire, de séduire les Métis, les affins réels.En analysant les différents types d'interactions que les Kakataibo ont avec leursadversaires, je me propose de saisir l'image qu'ils ont d'eux-mêmes, leur rapport à soi et la manière dont ils se projettent dans le réseaux social de la région. / ‘The Shipibo owe us a game!’ This statement by Kakataibo people expresses the binding character of the ceremonial exchange system in which they participate with their former enemies. The aim of this thesis is to provide an ethnography of the antagonistic relationship between these two groups of the Panoan language family of the Aguaytía basin in Peruvian Amazonia.The abandonment of warrior practices that were formerly the modus operandi privileged between these rivals, as well as the intensification of the contacts with the national society and ‘white people’ engendered new forms of relations between Kakataibo and Shipibo. Even if the figure of the ‘enemy’ remains indispensable for contemporary forms of identity constructions these are nolonger based on a logic of ontological predation. By using new ethnographic material, the thesis offers a new formulation of the theoretical propositions concerning sociality, and more specifically enmity, that has dominated amazonian anthropology for more than twenty years.From this point of view, the example of the native community festival is particularly relevant. A bargaining chip between opposing leaders, the various sequences of the festivity reveal the plurality of the relational forms which Kakataibo maintain with their various affines.On the one hand, the sorcery idiom which they mobilize to speak about football produces asymmetry and distance with their potential affines, such as the Shipibo. On the other, however, the Kakataibo girls performance of a white, beautiful, intelligent and eroticized woman during the beauty contest has the effect to seduce the Mestizos who are their real affines.Through describing various types of interactions the Kaktaibo have with their opponents, I simultaenously analyze the image Kakataibo have of themselves, their relationship to a notion of self, and the way they project themselves into regional social networks.

The banana is a major fruit grown by small and medium producers in the state of Alagoas. Most plantations are located in the region of forest and coastline, with favorable conditions for the development of diseases. This study aimed to make the lifting of the diseases in areas of the banana plantation of Alagoas and evaluate the alternative control of moko (Ralstonia solanacearum). The first stage was conducted during the years 2006 and 2007, making up visits and collection of plant material infected in 60 areas producing of banana, fourteen municipalities in the state. The material collected was subjected to procedures for identification of pathogens associated with plants. Detaching to the diseases caused by fungi and nematodes, and identified Yellow Sigatoka (Pseudocercospora musae); Deightoniella spot (Deightoniella torulosa) and Cordana spot (Cordana musae), a widespread occurrence; Chloridium spot (Chloridium musae), only in areas with shading and combined with other leaf spots; Exosporella spot, observed in Santana do Mundaú; fitonematoses caused by Rhadophulus similis, Helicotylenchus multicinctus and Pratylenchus sp., detected only in some municipalities; Panama disease (Fusarium oxysporum f.sp. cubense ) Found in four areas in the south of the state and Moko (R. solanacearum), in three areas. The alternative control of moko was the second stage of work, bearing in mind the significant losses that this disease causes the production of bananas. In the first experiment, isolates of rizobactérias were confronted, in the BDA, with a isolated of R. solanacearum, the method of streaks and incubated at 28 º C for 72 hours. Isolates RAB7, C110, C25, R14, HLT2, HRT4 and C11 induced a significant reduction in the growth of R. solanacearum. The bacteria selected in vitro were tested in the Banana plantlets, which had its roots wounds and immersed in the suspension of bacteria (108 cfu / mL) for a period of 20 minutes. Then, the seedlings were transplanted into pots with sterile substrate and incubated in a greenhouse, for 48 hours, when infestation of the substrate with a suspension of R. solanacearum (108 cfu / mL). According to statistical analyses the isolated RAB7 proved to be an interesting bacterial antagonist, followed by isolated C110, C25 and HLT2. In the second experiment, initially, it was evaluated different concentrations of essential oils of citronela, eucalyptus citriodora, clove and ginger: 1.25%, 3.5%, 3.75% and 5% and extracts of clove, ginger, cinnamon and melon (são-caetano): 5%, 10%, 15% and 20%, measuring up the halo of inhibition of bacteria after 48 hours of assembly of the experiment. The treatments involving eucalyptus oil and extracts of melon of San Caetano, clove and cinnamon did not differ from the witness. The extract of ginger, oils of citronela, clove and ginger differed significantly the level of 5%, inhibiting the growth of R. solanacearum, in all concentrations tested, stressing that the oil of clove, followed by extracts of ginger. Banana plantlets trees were sprayed with concentrations that showed better performance in vitro: oils of citronela, clove and ginger (3.75%) and extract of ginger (20%) up to 10 ml / plant. Eight days after the plantlets were inoculated with the pathogen (108 cfu / mL). The citronela oil provided the best result, with 100% control of the disease, however, caused fitotoxidez the plants. The oil and ginger extract, were similar in effectiveness to control moko (50%), oil and clove had lower efficiency (25%). In the third experiment, were tested organic residues, 10 and 20% (v / v): cassava raspas, shellfish gravels, chicken litter, banana leaves and ginger. In vitro, cassava raspas (10%) reduced the number of colonies and halos of inhibition. Significant results were further observed with ginger 20%, shellfish gravels, banana leaves (10 and 20%). In the experiment "in vivo" the substrate sterilized was infested with the pathogen (108 cfu / mL), mixed waste selected in vitro and incubated for 20 days. Banana plantlets were transplanted in pots with the treatments. Ginger and banana leaves (10%) had low rates of infection of the plants (25%) while the shellfish gravels (10 and 20%) presented, respectively, 75 and 50% symptoms of wilt. / Fundação de Amparo a Pesquisa do Estado de Alagoas / Doenças da bananeira (musa spp.) no estado de Alagoas e controle alternativo do moko (Ralstonia solanacearum (Smith) Yabuuchi et al.). A banana é uma das principais frutas cultivadas por pequenos e médios produtores no estado de Alagoas. A maioria dos plantios está localizada na zona da mata e litoral, com condições favoráveis ao desenvolvimento de doenças. Este trabalho teve como objetivos realizar o levantamento das doenças da bananeira em áreas de plantio de Alagoas e avaliar o controle alternativo do moko (Ralstonia solanacearum). A primeira etapa foi conduzida durante os anos de 2006 e 2007, fazendo-se visitas e coleta de material vegetal infectado em 60 áreas produtoras de banana, em quatorze municípios do estado. O material coletado foi submetido a procedimentos para identificação dos patógenos associados às plantas. Destacaram-se as doenças causadas por fungos e nematóides, sendo identificadas a sigatoka amarela (Pseudocercospora musae); a mancha de Deightoniella (Deightoniella torulosa); a mancha de Cordana (Cordana musae), todas de ocorrência generalizada; a mancha de Chloridium (Chloridium musae), somente em áreas com sombreamento excessivo e associada a outras manchas foliares; a mancha de Exosporella (Exosporella sp.) observada em baixa freqüência; as fitonematoses causadas por Rhadopholus similis, Helicotylenchus multicinctus e Pratylenchus sp., detectado apenas em alguns municípios; o mal do Panamá (Fusarium oxysporum f. sp. cubense) encontrado somente em quatro áreas no sul do estado e o moko (Ralstonia solanacearum), em três áreas.O controle alternativo do moko constituiu a segunda etapa do trabalho, tendo em vista as perdas significativas que esta doença provoca na produção da banana. No primeiro experimento, isolados de bactérias foram confrontados, em meio BDA, com um isolado de R. solanacearum, pelo método de estrias e incubados a uma temperatura de 28ºC durante 72 horas. Os isolados RAB7, C110, C25, R14, HLT2, HRT4, C11 induziram uma significativa redução do crescimento de R. solanacearum. As bactérias selecionadas in vitro foram testadas em mudas de bananeira, que tiveram suas raízes feridas e imersas na suspensão bacteriana (108 cel/mL), por um período de 20 minutos. Em seguida, as mudas foram transplantadas para vasos com substrato esterilizado e incubadas em casa de vegetação, por 48 horas, quando ocorreu a infestação do substrato com uma suspensão de R. solanacearum (108 cel/mL). De acordo com as análises estatísticas o isolado RAB7 mostrou-se um antagonista bacteriano, seguidos pelos isolados C110, C25 e HLT2. O isolado R14 apresentou a menor porcentagem de redução da severidade da doença. No segundo experimento, inicialmente, foram avaliadas diferentes concentrações de óleos essenciais de citronela, eucalipto citriodora, cravo-da-índia e gengibre: 1,25%; 3,5%; 3,75% e 5% e de extratos de cravo-da-índia, gengibre, canela e melão de São Caetano: 5%, 10%, 15% e 20%, medindo-se o halo de inibição da bactéria após 48 horas. O óleo de eucalipto e os extratos de melão-de-são-caetano, cravo-da-índia e canela não diferiram da testemunha. O extrato de gengibre, os óleos de citronela, de cravo e de gengibre diferiram significativamente da testemunha, inibindo o crescimento de R. solanacearum,em todas as concentrações testadas, destacando-se o óleo de cravo como o melhor tratamento, seguido por extrato de gengibre. Mudas de bananeira foram pulverizadas com as concentrações que apresentaram melhor desempenho in vitro: óleos de citronela e cravo (3,75%), óleo de gengibre (3,75%) e extrato de gengibre (20%), aplicando-se 10 ml da solução por planta. Oito dias após, as mudas foram inoculadas com o patógeno (108 cel/mL). O óleo de citronela proporcionou o melhor resultado, com 100% de controle da doença, porém as folhas das plantas com esse tratamento apresentaram sintomas de fitotoxidez. O óleo e o extrato de gengibre foram semelhantes na eficiência de controle do moko (50%), e o óleo de cravo apresentou menor eficiência (25%). No terceiro experimento foram testados os resíduos orgânicos raspas de mandioca, cascalhos de marisco, cama-de-frango, folhas de bananeira e gengibre nas concentrações de 10 e 20 % v/v. O melhor resultado foi observado no tratamento com raspas de mandioca 10 % com redução no número de colônias e presença de maior número de halos de inibição. Resultados significativos foram, ainda, observados nos tratamentos com gengibre 20% e cascalho de marisco e folhas de bananeira (10 e 20%), onde também houve aparecimento de halos de inibição. No experimento in vivo o substrato esterilizado foi infestado com o patógeno (108 cel/mL), misturado aos resíduos, secos e triturados, selecionados in vitro e incubado por 20 dias, em sacos de polietileno. Mudas de bananeira foram transplantadas para vasos com os tratamentos. Nos substratos contendo raspas de gengibre (10%) e folhas de bananeira (10%v/v) as plantas apresentaram baixos índices de infecção (25%) enquanto que nos tratamentos com cascalhos de marisco (10 e 20 %v/v) apresentaram, respectivamente, 75 e 50% de sintomas de murcha, demonstrando que houve diferença entre as dosagens. O tratamento com raspas de mandioca não diferiu da testemunha, com 100% das mudas apresentando sintomas de murcha e morte.

A total of 30 fungal fruiting bodies were collected from decaying plant materials (barks and litter) from the wild based on morphological variations. Nine of these fungi purified to monoaxenic cultures were included in the present study and also a type strain Ganoderma lucidum ATCC- 32471. These fungi were screened for lignocellulolytic activities, five of these organisms produced ligninolytic enzymes when exposed to two different concentrations of guaiacol (0.02% and 0.2%) on two different media (MEA and PDA). All ten fungal isolates screened for cellulolytic activity were positive for the production of the cellulase enzyme. The fungal isolates were characterised using morphological and molecular methods. Molecular characterization using ITS1 and ITS4 primers was able to identify these fungal isolates to degrees of accuracy ranging from 98% to 100%. The phylogenetic and lineage analysis showed that the species varied amongst phylum Basidiomycota, Ascomycota and early diverging fungal lineages Mucormycotina. Both monocultures and dual cultures of these 10 fungal species were cultivated for the purpose of spectrophotometrically quantifying and evaluating enzyme production on agricultural waste residues; corn cob, sugar cane bagasse and wheat straw. A pattern of antagonistic invasion interaction was identified to demonstrate increased enzyme production on dual cultures. Four of these fungal species, Trichoderma sp. KN10, Rhizopus microsporus KN2, Fomitopsis sp. KN1 and Coriolopsis sp. KN6 demonstrated tendencies of invasion and replacement in co-cultures. The fungi and their dual cultures showed varying levels of enzyme production. Analysis of mean showed dual culture interactions involving KN10 with values for MnP production approximately at 1.46U/ml compared to monoculture of 0.06U/ml. Further, dual laccase values approximately at 0.09U/ml compared to monocultures of 0.05U/ml. Overall the highest enzyme activity was observed using wheat straw. This study demonstrated and proved that agricultural waste residues can be used for lignocellulytic enzyme production and that antagonistic invasion by some fungi (in particular Trichoderma sp. KN10) in co-cultures can increase production of one or more of the three enzyme laccase, lignin peroxidase and manganese peroxidase. / Environmental Sciences / Ph. D. (Environmental Science)

Parmi les stratégies visant à contrôler la croissance de microorganismes pathogènes dans un aliment, la biopréservation qui s’appuie sur l’utilisation des capacités inhibitrices d’autres microorganismes offre une grande diversité d’opportunités. Il est cependant nécessaire de comprendre les mécanismes moléculaires et physiologiques régissant l’antagonisme du microorganisme protecteur vis-à-vis de la bactérie indésirable. L’objectif de cette thèse était de caractériser l’antagonisme de L. garvieae N201, isolé de fromage, vis-à-vis de souches de S. aureus par des approches in vitro : génomique, transcriptomique (ciblée concernant S. aureus, globale concernant L. garvieae) et phénotypique. Un acteur avait déjà été identifié : le peroxyde d’hydrogène (H2O2) produit par L. garvieae sous un niveau d’aération élevé. Lors de ces travaux de thèse, il a été montré que le peroxyde d’hydrogène serait également produit par L. garvieae sous une faible aération en quantité faible (indétectable par spectrophotométrie) mais suffisante pour induire une inhibition de S. aureus. Les gènes de production du H2O2 de L. garvieae (poxB, sodA) seraient exprimés constitutivement quel que soit le niveau d’aération. Les gènes de dégradation du H2O2 (katA, sodA, ahpC / ahpF) seraient plutôt surexprimés sous une faible aération, suggérant leur rôle dans un mode de contrôle de la concentration en H2O2 autogène par L. garvieae. En parallèle, trois autres mécanismes potentiellement impliqués dans l’antagonisme ont été mis en évidence : i) la répression de gènes de réponse au stress (clpC, ctsR, dnaK) de S. aureus par L. garvieae et l’aération, ii) la répression de gènes de division cellulaire de S. aureus (mraZ, mraW, potentiellement le cluster dcw) par L. garvieae, iii) la production d’un effecteur extracellulaire par L. garvieae dont la nature reste à caractériser. Ajouté à cela, la présence de L. garvieae modulerait l’expression des principaux gènes de virulence de S. aureus, réprimant ceux codant pour les entérotoxines sous une faible aération. Ainsi, la souche L. garvieae N201 s’est révélée être une candidate intéressante comme agent de biopréservation. Cependant, son innocuité pour l’Homme devra être vérifiée et son antagonisme sur S. aureus devra être évalué en matrice alimentaire. Les données générées ainsi que la démarche développée pourront être utilisées afin d’étudier des interactions entre d’autres espèces d’intérêt et dans des écosystèmes différents. / Among strategies aiming to control the growth of spoilage microorganisms in food, the biopreservation is based on the inhibitory capacities of other microorganisms and presents a considerable variety of opportunities. A good understanding of the molecular and physiologic mechanisms underlying the antagonism of the preservative microorganism against the spoilage bacterium is also required. This thesis aimed to characterize the antagonism of L. garvieae N201 dairy strain against S. aureus strains combining in vitro strategies: genomic, transcriptomic (targeted concerning S. aureus, global concerning L. garvieae) and phenotypic. The involvement of hydrogen peroxide (H2O2) produced by L. garvieae under high aeration was already known. Although H2O2 concentration was undetectable using spectrophotometry method, it was produced by L. garvieae under low aeration at sufficient concentration to induce S. aureus inhibition. L. garvieae H2O2 -synthesis genes (poxB, sodA) seemed constitutively expressed whatever the aeration level. L. garvieae H2O2-degradation (katA, sodA, ahpC / ahpF) genes were overexpressed under low aeration, suggesting their involvement in control of autogenous H2O2 level. In parallel, three other mechanisms may be involved in this antagonistic relationship: i) the repression of S. aureus stress-response genes (clpC, ctsR, dnaK) by L. garvieae and / or under high aeration, ii) the repression of S. aureus cell-division genes (mraZ, mraW and probably the dcw cluster) by L. garvieae, iii), the production by L. garvieae of an extracellular effector which has to be characterized. Additionally, L. garvieae can modulate the expression of S. aureus major virulence genes, repressing those coding for enterotoxins under low aeration. Thus, L. garvieae N201 turned out to be an interesting candidate for biopreservative applications. However, its safety for humans should be approved and its antagonism against S. aureus has to be investigated in food matrices. The data resulting from this work may be used to study other interactions between other valuable species and in other ecosystems.

L'œuvre de Martín Kohan (Buenos Aires, 1967), écrivain prolifique à la notoriété grandissante au sein de la littérature argentine contemporaine, est l'objet de ce travail de recherche. Nous abordons le corpus – constitué par l'essentiel de l'œuvre : huit romans sur les neuf publiés à ce jour, La pérdida de Laura (1993), El informe. San Martín o el otro cruce de los Andes (1997), Los cautivos. El exilio de Echeverría (2000), Dos veces junio (2002), Segundos afuera (2005), Museo de la Revolución (2006), Ciencias morales (2007), Cuentas pendientes (2010); et deux recueils de nouvelles, Muero contento (1994), et Una pena extraordinaria (1998), principalement – sous l'angle de l'antagonisme, motif essentiel de l'univers fictionnel de Kohan, non seulement sur le plan de la diégèse mais également sur celui de la forme. Ce travail part de l'observation d'une constante au sein d'un corpus pourtant très varié : un rapport dichotomique, fait d'incompréhension et parfois de violence, entre la culture populaire ou la culture de masse, et la culture lettrée. La première partie de la thèse en propose une analyse systématique dans les cinq romans qui abordent explicitement ce type de conflit sous les modalités les plus diverses. La deuxième partie explore d'autres procédés qui tendent à confirmer le rôle structurant de l'antagonisme au sein de l'œuvre : si la mise à mal de l'union amoureuse semble exprimer la fatalité du malentendu, la dévalorisation des personnages du « milieu » et de la figure du consensus d'une part, et l'aspect revigorant des conflits menés à leur dernière extrémité d'autre part, révèlent l'aspect positif et particulièrement dynamique de l'antagonisme. La dernière partie se consacre aux implications de ce motif, omniprésent au point de représenter une nécessité : sur le plan politique – car sans être réaliste, la littérature de Kohan met en action la révolution marxiste en élaborant des figures de contre-pouvoir – ; sur le plan littéraire, où l'antagonisme montre toute sa fécondité. Le rapport hypertextuel, établi notamment avec des textes qui font autorité dans la littérature nationale, en est une expression essentielle ; mais la dichotomie est aussi une composante qui se manifeste à tous les niveaux de l'écriture, de l'unité minimale du mot à l'architecture complexe des romans. À la lutte entre personnages fait écho celle – défi formel le plus ambitieux – qui se joue entre le fond et la forme, source d'inépuisable ambivalence qui constitue l'une des spécificités les plus intéressantes de cet écrivain brillant. / The purpose of this study is to examine the literary work of Martin Kohan (Buenos Aires, 1967), prolific and increasingly renowned writer in contemporary Argentinian literature. We analyse the corpus – made up of the essential of his work: eight novels out of the nine published so far, La pérdida de Laura (1993), El informe. San Martín o el otro cruce de los Andes (1997), Los cautivos. El exilio de Echeverría (2000), Dos veces junio (2002), Segundos afuera (2005), Museo de la Revolución (2006), Ciencias morales (2007), Cuentas pendientes (2010); and two collections of short stories, Muero contento (1994), and Una pena extraordinaria (1998), mainly – from the perspective of antagonism, an essential pattern in terms of diegesis but also in terms of form. The starting point of this study is the observation of a constant within a diverse work: a dichotomous relationship made of incomprehension and sometimes violence between popular culture and literate culture. The first part of the thesis consists of a systematic analysis of the dichotomy in the five novels which explicitly explores this type of conflict. The second part examines other devices that tend to confirm the structuring role of antagonism throughout Kohan's fictions : love's defeat seems to express the fatality of misunderstanding, yet the depreciation of the middle characters and of consensus on the one hand, and the invigorating nature of conflicts when driven to their end on the other hand, reveal the positive and particularly dynamic aspect of antagonism. The last part focuses on the implications of this pattern which perbades to the point of becoming a necessity: on a political level– although Kohan's literature is not realistic, it activates the Marxist revolution by developing counter-power figures –; in literary terms, where antagonism proves a productive force. The hypertextual relation, set up especially with seminal national pieces, is an essential expression of this productivity but the dichotomy also operates at every level of writing, from the minimal unit of the word to the whole architecture of the novels. Echoing the conflicts between the characters is another type of conflic – the utmost formal challenge, that opposing form and content, an inexhaustible source of ambivalence which represents one of the most interesting features of this brilliant author.