Over the years, secondary metabolites have proven to be significant in the discovery of novel antibiotics and/or lead compounds. Various secondary metabolites have been reported to be produced by fungus of the genus, Alternaria. Here we report the isolation of secondary metabolites by the bioassay-guided fractionation of the ethyl acetate extract of fermentation cultures of the fungus, Alternaria tenuissima. This fungal strain was isolated from the soil underlying the lichen, Peltigera didactyla; and the lichen was collected from Wapusk National Park, a location in Northern Manitoba. The compounds isolated from the fungus include deoxyphomalone, dimethyl 4-methyl-2,6-pyridinedicarboxylate, stemphyperylenol and N-Methyl pyrrolidinone. Their structures were determined by comprehensive analysis of their spectroscopic data including FT-IR, mass spectrometry, 1D and 2D NMR; and their bioactivities were tested against E. coli cells. Some of the compounds demonstrated some bioactivity. The taxonomic identity of the fungus was confirmed by ITS sequencing of its ribosomal DNA.

Over the years, secondary metabolites have proven to be significant in the discovery of novel antibiotics and/or lead compounds. Various secondary metabolites have been reported to be produced by fungus of the genus, Alternaria. Here we report the isolation of secondary metabolites by the bioassay-guided fractionation of the ethyl acetate extract of fermentation cultures of the fungus, Alternaria tenuissima. This fungal strain was isolated from the soil underlying the lichen, Peltigera didactyla; and the lichen was collected from Wapusk National Park, a location in Northern Manitoba. The compounds isolated from the fungus include deoxyphomalone, dimethyl 4-methyl-2,6-pyridinedicarboxylate, stemphyperylenol and N-Methyl pyrrolidinone. Their structures were determined by comprehensive analysis of their spectroscopic data including FT-IR, mass spectrometry, 1D and 2D NMR; and their bioactivities were tested against E. coli cells. Some of the compounds demonstrated some bioactivity. The taxonomic identity of the fungus was confirmed by ITS sequencing of its ribosomal DNA.

In rural inland, south-eastern Australia, allergy to the fungus Alternaria is prevalent and an important risk factor for asthma. The aim of the thesis was to investigate the distribution and factors influencing allergens of Alternaria in the air. As airborne allergenic spores were thought to arise from harvesting of nearby crops, two towns with different agricultural practices were studied. Moree has two crop harvesting periods in summer and autumn whilst Wagga Wagga has one harvesting period in summer. Over two years, air was sampled daily in Wagga Wagga and Moree using Burkard traps. The reliability of measurements from a single site to represent the distribution of airborne concentrations of spores across each town was examined using data from three traps simultaneously, sited 2.0 to 4.9 km apart, over four weeks. Substantial intra-class correlation coefficients (ICC) were observed between the three sampling sites across both towns (ICC=0.52, 95% CI 0.30-0.71 to 0.76, 95% CI 0.61-0.87) when counts of Alternaria spores were relatively high. The correlation was poor when counts were low. Of more than 365 trap tapes examined, the two microscopic traverses strongly correlated for counts of Alternaria spores (ICC=0.95, 95% CI 0.94-0.96). Alternaria was detected in both towns throughout the two year period with peaks in spore concentrations reflecting the season of crop harvesting in each region. Individual exposure to spores was examined. Thirty three subjects (adults and children from nine families) wore nasal air samplers and personal air samplers both inside and outside their homes. The effects of activity, location, age on the inhalation of Alternaria spores and variation between individuals in the same environment were determined. Every subject inhaled Alternaria spores. Personal exposure to Alternaria in the home environment varied substantially between subjects. Levels of fungal spores inhaled were higher during periods of activity than during rest, and higher while subjects were outdoors than indoors. During outdoor activity, the number of Alternaria spores inhaled ranged from 4 to 794 (median 11) spores/hr. Sources of airborne spores was investigated by sampling air above wheat and cotton crops near the towns during harvesting and non-harvesting periods, in a grain and cotton seed storage shed, and a cotton gin. Substantially higher concentrations were detected above crops during harvesting periods compared to non-harvesting periods. Peaks were associated with harvesting and other activities where plants were manipulated. By regression analysis spore concentrations in both towns were modelled against those detected above crops and with weather variables. Only one crop sampling period (cotton harvest) independently correlated with concentrations in town. Analysis combining all data showed concentrations of spores above crops correlated with spore concentrations in the town when lagged by one day. Variables of rainfall and maximum temperature influenced concentrations in both towns, and wind direction in Wagga Wagga alone. Parents of asthmatic children were asked by questionnaire in which locations symptoms were provoked. Asthma was reported to be exacerbated at grain farms and with disturbance of local vegetation in town and home gardens. Nasal sampling confirmed that activities that disturbed dust or vegetation increased the inhalation of spores. The factors that release allergen from spores were determined in a modified Halogen immunoassay. Approximately 60% of spores released allergen, and the proportion was influenced by isolate, nutrient availability, viability, and not influenced by sunlight or culture age up to 21 days. Germinating the spores significantly increased the proportion that released total allergen and Alt a 1 (p<0.0001). Alt a 1 appears to be a minor contributor to the total allergen released from spores except when spores have germinated. Conclusions: People living in inland rural regions of Australia are exposed to substantial quantities of allergenic spores of Alternaria. Exposure is a highly personal event and is largely determined by disturbance of local vegetation releasing spores such as from nearby crops by wind, harvesting, slashing, transport and processing of produce, and from within town and home gardens. Most spores inhaled are likely to be allergenic, with potency potentially increasing with viability.

Made available in DSpace on 2016-06-02T19:30:12Z (GMT). No. of bitstreams: 1 6721.pdf: 2764879 bytes, checksum: ca82bcb193d5ae0d2e21032afd6ed1dd (MD5) Previous issue date: 2015-03-30 / Financiadora de Estudos e Projetos / The Brazilian savanna holds the richest flora among the tropical savannas, being one of the hot spots for conservation of the biodiversity in the world. However, the chemical potential of its plant species is still underused while deforestation and loss of biodiversity are main issues. In the Brazilian savanna, plants are exposed to environmental pressures (competition, pathogens, drought, injurious UV radiation, etc) that may stimulate the production of secondary metabolites as a defense. These compounds can generally be explored due to their biological properties. The aim of this study was to assess the fungicidal and antioxidant properties of plants from the Brazilian savanna. First a screening was conducted with ethanolic leaf extracts of 28 plant species. There was no activity against Alternaria alternata, a filamentous fungi that causes one of the most severe diseases in tangerines (Alternaria brown spot disease). However, the same extracts presented a high antioxidant potential associated with the phenolic content. Other investigations were made using infusion extractions focusing on the Myrtaceae family, one of the most abundant families of plants in the Brazilian savanna. Most species also presented high antioxidant activity and phenolic content. At last, the extraction of piceid, a compound with high antioxidant activity, was optimized from roots of Psidium laruotteanum. A response surface methodology was applied to assess the influence of solvent, pH, amplitude, cycle, temperature and solvent-solid ratio using an ultrasound extraction. A high amount of piceid was extracted and Psidium laruotteanum root was found to be the most concentrated source of this compound reported up to date. These results point the plant species from the Brazilian savanna as an important source of bioactive compounds, emphasizing the need to preserve and study its biodiversity. / O cerrado possui a flora mais rica entre as savanas tropicais, sendo um dos pontos quentes para conservação da biodiversidade no mundo. No entanto, o potencial químico de suas espécies vegetais é ainda subutilizado, enquanto o desmatamento e a perda de biodiversidade são questões de grande relevância. No cerrado, as plantas estão expostas a pressões ambientais (competição, patógenos, seca, radiação UV nociva, etc) que podem estimular a produção de metabólitos secundários como defesa. Estes compostos geralmente podem ser explorados devido suas propriedades biológicas. O objetivo deste estudo foi avaliar as propriedades fungicidas e antioxidante de plantas do cerrado. Primeiro uma triagem foi realizada com extratos etanólicos de folhas de 28 espécies vegetais. Não houve nenhuma atividade contra Alternaria alternata, um fungo filamentoso que causa uma das doenças mais severas em tangerinas (mancha marrom de Alternaria). No entanto, os mesmos extratos apresentaram um potencial antioxidante elevado associado com o conteúdo fenólico. Outras investigações foram feitas usando extrações por infusão enfocando a família Myrtaceae, uma das famílias mais abundantes de plantas no cerrado. A maioria das espécies apresentou alta atividade antioxidante e alto conteúdo fenólico. Por fim, a extração de piceido, um composto com alta atividade antioxidante, foi otimizada de raízes de Psidium laruotteanum. Uma metodologia de superfície de resposta foi aplicada para avaliar a influência do solvente, pH, amplitude, ciclo, temperatura e razão solvente-sólido usando uma extração de ultrasonido. Uma alta quantidade de piceido foi extraída e a raiz de Psidium laruotteanum se mostrou como sendo a fonte mais concentrada deste composto relatada até hoje. Estes resultados apontam as espécies de plantas do cerrado como uma importante fonte de compostos bioativos, enfatizando a necessidade de preservar e estudar sua biodiversidade.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-23T12:15:14Z No. of bitstreams: 1 Priscilla Anunciada Alves Moreira.pdf: 1192520 bytes, checksum: f783ff4175972095251ac5f078d7fe19 (MD5) / Made available in DSpace on 2017-03-23T12:15:14Z (GMT). No. of bitstreams: 1 Priscilla Anunciada Alves Moreira.pdf: 1192520 bytes, checksum: f783ff4175972095251ac5f078d7fe19 (MD5) Previous issue date: 2008-08-06 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The Alternaria black spot is considered one of the most common and destructive diseases of brassica, and although it may be caused by several species, Alternaria brassicicola is the predominant pathogen in both conventional and organic brassica crops in State of Pernambuco, Brazil. To assess the pathogenic variability of 120 isolates of A. brassicicola, was analyzed the virulence to brassica species, physiology aspects of the pathogen and sensitivity to fungicides. The isolates obtained from conventional and organic crops were inoculated under greenhouse conditions in 40 days old plants of broccoli, cabbage, cauliflower and Chinese cabbage and disease severity was assessed 10 days after the inoculation. Under laboratory conditions the following parameters were evaluated for all isolates: rate of growth mycelial, sporulation, and sensitivity to fungicides iprodione and tebuconazole. Based on the variables analyzed, it was found variability among isolates of A. brassicicola, but there were no significant (P>0.05) correlation among the analyzed variables, regardless of the cultivation system and the original host of each isolate. The variables were useful in distinguishing individual groups of isolated with similarity in virulence to the host, physiological characteristics and sensitivity to fungicides. The cross inoculations and the development of symptoms in brassica highlighted the absence of host specificity. All isolates weresensitive to the fungicides iprodione and tebuconazole. Based on the components of variance analysis, there was no significant effect of the cultivation system on the variables, except for disease severity on Chinese cabbage (P = 0.0391). Most of the variance results from the difference among isolates of A. brassicicola within the cropping systems and the host of origin. In the context multivariate, no effect was found regarding the host of origin of the isolates (P = 0.4993), however, there was great variability (P <0.0001) among isolates within the cropping systems and the host of origin. / A alternariose é considerada uma das doenças mais comuns e destrutivas das brássicas, e embora possa ser causada por várias espécies, Alternaria brassicicola é o agente patogênico predominante nos plantios convencionais e orgânicos de brássicas no Estado de Pernambuco, Brasil. Para avaliar a variabilidade patogênica de 120 isolados de A. brassicicola, foi analisada a virulência a espécies de brássicas, aspectos relacionados à fisiologia do patógeno e sensibilidade a fungicidas. Os isolados obtidos de cultivos convencionais e orgânicos foram inoculados em plantas de brócolis, couve-chinesa, couve-comum e couve-flor com 40 dias de idade, em casa de vegetação, onde a severidade da doença foi avaliada 10 dias após a inoculação. Em condições de laboratório, os isolados foram avaliados quanto a taxa de crescimento micelial, esporulação e sensibilidade aos fungicidas iprodione e tebuconazole. Com base nas variáveis analisadas, foi constatada a existência de variabilidade entre os isolados de A. brassicicola, mas não foram observadas correlações significativas (P=0,05) entre as variáveis avaliadas, independentemente do sistema de cultivo e do hospedeiro de origem dos isolados. As variáveis individuais foram úteis na distinção de grupos de isolados do patógeno com similaridade na virulência às hospedeiras, características fisiológicas e sensibilidade aos fungicidas. As inoculações cruzadas e o desenvolvimento de sintomas nas brássicas evidenciou a inexistência de especificidade por hospedeiro entre os isolados do patógeno. Todos os isolados foram sensíveis aos fungicidas iprodione e tebuconazole. Pela análise dos componentes de variância, não houve efeito significativo do sistema de cultivo sobre as variáveis analisadas, com exceção para severidade em couve-chinesa (P=0,0391). A maior parte da variância foi resultante da diferença entre os isolados de A. brassicicola dentro dos sistemas de cultivo e dos hospedeiros de origem. No contexto multivariado, não se constatou efeito do hospedeiro de origem dos isolados (P=0,4993), porém, houve grande variabilidade (P<0,0001) entre os isolados dentro dos sistemas de cultivo e dos hospedeiros de origem.

Alternaria dauci e A. solani são duas espécies de fungos fitopatogênicos reconhecidamente difíceis de esporular em meio de cultura. Isto dificulta as inoculações artificiais e, conseqüentemente, prejudica o processo de seleção de genótipos de cenoura e tomate resistentes às doenças causadas por estes fungos. Este trabalho teve o objetivo de verificar a influência de alguns fatores, aplicados na incubação, sobre o crescimento micelial e esporulação das duas espécies fúngicas. Diferentes meios de cultura (BDA, aveia e V8), temperatura (15, 20, 25, 30 e 35 &#176;C), comprimentos de onda da luz usada na incubação (amarela, azul, branca, NUV, verde e vermelha), tipos de estresse aplicado à colônia (raspagem, UV, irradiação de microondas e temperatura de 100 &#176;C) e fotoperíodos (luz / escuro, respectivamente, de 24 h / 0 h, 22 h / 2 h, 17 h / 7 h, 12 h / 12 h, 7 h / 17 h, 2 h / 22 e 0 h / 24 h) foram testados. Após a determinação dos melhores fatores, o método desenvolvido neste trabalho foi comparado ao método tradicionalmente utilizado (BDA, 25 &#176;C, 12 h luz branca / 12 h escuro e raspagem da colônia), utilizando diversos isolados de ambas as espécies. Os resultados indicaram o meio V8-ágar e a temperatura de 25 &#176;C como os mais favoráveis ao crescimento e esporulação. Os diferentes comprimentos de onda utilizados tiveram influência marcante na esporulação, sendo o NUV o mais estimulante. Todos os tipos de estresse aplicados induziram esporulação, porém, a raspagem das colônias proporcionou os melhores resultados. O fotoperíodo 12 h luz NUV / 12 h escuro foi o que mais estimulou a esporulação. Observou-se que, de modo geral, períodos de escuro maiores que os períodos de luz aplicados após o estresse da colônia, favoreceram a esporulação. Dessa forma, o processo desenvolvido neste trabalho consistiu de incubação em meio V8-ágar, temperatura de 25 &#176;C, raspagem da colônia e fotoperíodo de 12 h luz NUV / 12 h escuro. Este procedimento mostrou-se nitidamente superior ao tradicionalmente utilizado para crescimento e esporulação de ambas as espécies. / Alternaria dauci e Alternaria solani are two phytopathogenic fungus species known for difficult sporulation in culture media. This hampers artificial inoculations and, consequently, affects the selection process of carrot and tomato genotypes resistant to the diseases caused by these fungi. This study had the objective of verifying the influence of some factors applied during incubation on mycelia growth and sporulation of the two fungus species. Different culture media (BDA, oat and V8), temperature (15, 20, 25, 30 and 35 &#176;C), light wavelengths during incubation (yellow, blue, white, NUV, green, and red), stress types applied to the colony (scratching, UV, microwave irradiation, and temperature of 100 &#176;C) and photoperiods (light / dark, respectively, of 24 h / 0 h, 22 h / 2 h, 17 h / 7 h, 12 h / 12 h, 7 h / 17 h, 2 h / 22 h and 0 h / 24 h) were tested. Upon determination of the best factors, the method developed in this study was compared to the traditional procedure (BDA, 25 &#176;C, 12 h white / 12 h dark light and scratching of the colony), with different isolates of both species. Results indicated the V8-agar media and a temperature of 25 &#176;C as most favorable for growth and sporulation. The different wavelengths had a marked influence on sporulation and NUV was the most stimulating. All applied stress types induced sporulation, but best results were obtained with scratching of the colonies. The 12 h light / 12 h dark photoperiod stimulated sporulation most. In general, longer dark than light periods after the stress of the colony favored sporulation. The procedure developed in this study consisted of incubation in V8-agar media, a temperature of 25 &#176;C, scratching of the colony and a 12 h light / 12 h dark photoperiod. This process is clearly superior to the traditional method for growth and sporulation of both species.

Alternaria dauci e A. solani são duas espécies de fungos fitopatogênicos reconhecidamente difíceis de esporular em meio de cultura. Isto dificulta as inoculações artificiais e, conseqüentemente, prejudica o processo de seleção de genótipos de cenoura e tomate resistentes às doenças causadas por estes fungos. Este trabalho teve o objetivo de verificar a influência de alguns fatores, aplicados na incubação, sobre o crescimento micelial e esporulação das duas espécies fúngicas. Diferentes meios de cultura (BDA, aveia e V8), temperatura (15, 20, 25, 30 e 35 &#176;C), comprimentos de onda da luz usada na incubação (amarela, azul, branca, NUV, verde e vermelha), tipos de estresse aplicado à colônia (raspagem, UV, irradiação de microondas e temperatura de 100 &#176;C) e fotoperíodos (luz / escuro, respectivamente, de 24 h / 0 h, 22 h / 2 h, 17 h / 7 h, 12 h / 12 h, 7 h / 17 h, 2 h / 22 e 0 h / 24 h) foram testados. Após a determinação dos melhores fatores, o método desenvolvido neste trabalho foi comparado ao método tradicionalmente utilizado (BDA, 25 &#176;C, 12 h luz branca / 12 h escuro e raspagem da colônia), utilizando diversos isolados de ambas as espécies. Os resultados indicaram o meio V8-ágar e a temperatura de 25 &#176;C como os mais favoráveis ao crescimento e esporulação. Os diferentes comprimentos de onda utilizados tiveram influência marcante na esporulação, sendo o NUV o mais estimulante. Todos os tipos de estresse aplicados induziram esporulação, porém, a raspagem das colônias proporcionou os melhores resultados. O fotoperíodo 12 h luz NUV / 12 h escuro foi o que mais estimulou a esporulação. Observou-se que, de modo geral, períodos de escuro maiores que os períodos de luz aplicados após o estresse da colônia, favoreceram a esporulação. Dessa forma, o processo desenvolvido neste trabalho consistiu de incubação em meio V8-ágar, temperatura de 25 &#176;C, raspagem da colônia e fotoperíodo de 12 h luz NUV / 12 h escuro. Este procedimento mostrou-se nitidamente superior ao tradicionalmente utilizado para crescimento e esporulação de ambas as espécies. / Alternaria dauci e Alternaria solani are two phytopathogenic fungus species known for difficult sporulation in culture media. This hampers artificial inoculations and, consequently, affects the selection process of carrot and tomato genotypes resistant to the diseases caused by these fungi. This study had the objective of verifying the influence of some factors applied during incubation on mycelia growth and sporulation of the two fungus species. Different culture media (BDA, oat and V8), temperature (15, 20, 25, 30 and 35 &#176;C), light wavelengths during incubation (yellow, blue, white, NUV, green, and red), stress types applied to the colony (scratching, UV, microwave irradiation, and temperature of 100 &#176;C) and photoperiods (light / dark, respectively, of 24 h / 0 h, 22 h / 2 h, 17 h / 7 h, 12 h / 12 h, 7 h / 17 h, 2 h / 22 h and 0 h / 24 h) were tested. Upon determination of the best factors, the method developed in this study was compared to the traditional procedure (BDA, 25 &#176;C, 12 h white / 12 h dark light and scratching of the colony), with different isolates of both species. Results indicated the V8-agar media and a temperature of 25 &#176;C as most favorable for growth and sporulation. The different wavelengths had a marked influence on sporulation and NUV was the most stimulating. All applied stress types induced sporulation, but best results were obtained with scratching of the colonies. The 12 h light / 12 h dark photoperiod stimulated sporulation most. In general, longer dark than light periods after the stress of the colony favored sporulation. The procedure developed in this study consisted of incubation in V8-agar media, a temperature of 25 &#176;C, scratching of the colony and a 12 h light / 12 h dark photoperiod. This process is clearly superior to the traditional method for growth and sporulation of both species.

Resumo: Com o objetivo da redução da aplicação de fungicidas na produção de alho, foram estudados os efeitos dos Microrganismos Eficazes (E.M.-4 e E.M.-5) sobre o controle da mancha púrpura, a produção da cultura e as propriedades físicas, químicas e biológicas do solo. Os experimentos foram conduzidos, em condições de campo, por dois e três anos, na Fazenda de Ensino, Pesquisa e Produção da Unesp em São Manuel, SP. O E.M. foi aplicado nos bulbilhos de alho antes do plantio, adicionado ao material orgânico incorporado ao solo e pulverizado nas plantas após incubação ou não com melaço. A utilização do E.M. + melaço (não incubado) não proporcionou controle da doença nos experimentos. No entanto, com a incubação do E.M. + melaço houve redução na severidade da mancha púrpura em um experimento e incremento na emergência e número de folhas verdes por planta em ambos os experimentos. A altura das plantas, superbrotamento, produção, bulbos de maior valor comercial (classes 5+6+7) e as propriedades físicas (densidade do solo, condutividade hidráulica, estabilidade dos agregados, resistência à penetração e infiltração de tinta), químicas e biológicas do solo (conteúdo de polissacarídeos, carbono da biomassa microbiana do solo e atividade da desidrogenase) não foram alteradas pela utilização do E.M. A adição de material orgânico ao solo promoveu maior agregação do solo (estabilidade dos agregados), independentemente dos tratamentos empregados. No entanto, a densidade do solo, a condutividade hidráulica e a resistência à penetração não sofreram alterações com a adição do material orgânico. / Abstract: With the purpose to reduce fungicides application for garlic production, the effects of Effective Microorganisms (E.M.-4 and E.M.-5) were studied on the control of garlic purple blotch, garlic yield and physical, chemical and biological properties of the utilized planting soil. Experiments were carried out under field conditions, for two and three years, an experimental farm, belonging to São Paulo State University, located in São Manuel, São Paulo, Brazil. E.M. was applied on garlic cloves before planting, additioned to the incorporated organic matter and sprayed on garlic aerial part after incubation or not with molasse. When E.M. plus molasse (not incubated) was utilized the control of purple blotch was not observed in two experiments. However, with the incubation of E.M. with molasse, the results showed a reduction of purple blotch severity in one experiment as well as an increment of seedling emergency and number of green leaves per plant in two experiments. Plant height, bulbil sprouting, yield, bulbs with higher market grades (classes 5+6+7) and soil physical (bulk density, hidraulic conductivity, stable soil aggregates, resistance to soil penetration and tint infiltration) chemical and biological (polyssacharides, carbon of microbial biomass and dehydrogenase content) proprieties were not affected by E.M. utilization. Organic matter addition promoted soil agreggation in all treatments, however, soil bulk density, hidraulic conductivity and resistance to soil penetration was not changed by organic matter addition. / Orientador: Chukichi Kurozawa / Coorientador: Roberto Lyra Villas-Bôas / Banca: Chukichi Kurozawa / Banca: Julio Nakagawa / Banca: Rumy Goto / João Batista Vida / Hasime Tokeshi / Doutor

A ceratite fúngica (CF) é uma micose ocular oportunística, que tem como sítio de infecção a córnea. Não é uma enfermidade de risco de vida, mas de extremo comprometimento visual e dificuldade terapêutica e, em casos graves, podendo levar à cegueira total ou mesmo a perda do globo ocular. O trabalho objetivou identificar os agentes etiológicos causadores da CF, e descrever os critérios terapêuticos empregados. No período de 1998 a 2011 foram estudados 23 casos de CF diagnosticados no Laboratório de Micologia da Irmandade da Santa Casa de Misericórdia de Porto Alegre / RS. Foram analisados os aspectos demográficos, as doenças de base e os fatores associados ao desenvolvimento da doença, assim como os critérios terapêuticos. No presente estudo, a mediana de idade foi 45 anos, com variação entre 15 e 76 anos, com predomínio do gênero masculino. Os fungos filamentosos figuraram em 78% (18/23) dos casos analisados, sendo o gênero Fusarium spp. o agente etiológico de maior frequência. Concluiu-se que uma compreensão epidemiológica local e a identificação dos fatores de risco, agregados ao diagnóstico micológico precoce e eficaz, são fundamentais na prevenção e correta conduta terapêutica da CF no Rio Grande do Sul, sendo que estas práticas evitarão complicações de perda do globo ocular, melhorando o prognóstico oftalmológico do paciente. / The fungal keratitis is an ocular opportunistic mycosis, which has the cornea as site of infection. Isn’t a life-threatening disease, but with extreme visual impairment and therapeutic difficulty, which can lead to total blindness or even loss of the eyeball, in severe cases. The study aimed to identify the etiologic agents causing fungal keratitis, and describe the therapeutic criteria used. In the period 1998 to 2011 were retrospectively studied 23 cases of fungal keratitis diagnosed at the Mycology Laboratory of Irmandade Santa Casa de Misericórdia Hospital of Porto Alegre / RS. We analyzed the demographics, underlying diseases and the factors associated with disease development, as well as therapeutic criteria. In this study, the median age was 45 years old, ranging between 15 to 76 years old, predominantly male. The filamentous fungus corresponded to 78% (18/23) of the cases analyzed, and Fusarium spp. has been the etiologic agent of highest frequency. It was concluded that an understanding of local epidemiological and identification of risk factors, added to the early and effective mycological diagnosis are essential to prevent and correct therapeutic approach for fungal keratitis in Rio Grande do Sul. These practices will prevent complications of loss of the eyeball, improving the ophthalmological prognosis of the patient.

La transmission à et par la semence correspond à une étape critique dans l'épidémiologie de nombreuses maladies et permet aux microorganismes pathogènes de survivre et d'assurer leur dispersion. Afin d'étudier les mécanismes impliqués dans la transmission à et par la semence, deux pathosystèmes modèles ont été mis au point. Deux agents pathogènes, une bactérie (Xanthomonas campestris pv. campestris), et un champignon (Alternaria brassicicola) ont été sélectionnés pour étudier leur transmission à et par la graine de la plante hôte modèle Arabidopsis thaliana. Nous avons montré par microscopie confocale à balayage laser que la colonisation de la hampe florale par X. campestris pv. campestris est strictement confinée aux tissus vasculaires du xylème. Une approche par microscopie électronique à balayage a permis d'identifier les différentes voies de pénétration d'A. brassicicola dans la silique d'A. thaliana et le mode de colonisation des graines. L'un (Xcc2828, xytA) des deux transporteurs TonB-dépendants testés intervient dans la colonisation des valves et graines mais pas dans la colonisation du xylème de la hampe florale montrant une probable spécificité de ce TBDT pour les xylanes des parois primaires. Nous avons montré que deux facteurs o54 (Xcc1935 Xcc2802) régulent différentiellement l'expression de gènes impliqués dans la mobilité et la formation de bio ilms chez X. campestris pv. Campestris, fonctions indispensables à la transmission à et par la graine. D'autre part, une histidine kinase de groupe III osmosenseur, la proteine AbNik1, intervient lors de la colonisation des graines d'A. thaliana par A. brassicicola.