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Estudo da interacção do fungo saprófita Hypholoma fasciculare com microrganismos filamentosos e seu efeito no crescimento de plantas de castanheiro

Pereira, Eric Carvalho
Fonte: Instituto Politécnico de Bragança, Escola Superior Agrária Publicador: Instituto Politécnico de Bragança, Escola Superior Agrária
Tipo: Dissertação de Mestrado
POR
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17.11%
Hypholoma fasciculare é um fungo saprófita-lenhícola muito comum nos povoamentos de Castanea sativa na região do nordeste transmontano. Nos últimos anos, esta espécie tem sido explorada como agente de controlo biológico, por ser muito combativa contra espécies patogénicas. O presente trabalho tem como objectivo geral avaliar o potencial do H. fasciculare como agente de controlo biológico; e o efeito da sua aplicação nos fungos ectomicorrízicos bem como nas plantas de castanheiro e no processo de micorrização pelo Pisolithus tinctorius. A avaliação do potencial do H. fasciculare como agente de controlo biológico, foi efectuada em condições in vitro pelo método da cultura dupla. O fungo H. fasciculare inibiu significativamente o crescimento dos patogéneos Armillaria mellea e Phytophthora cambivora, e dos fungos micorrízicos Suillus luteus e Pisolithus tinctorius. Os mecanismos adoptados pelo H. fasciculare foram “antagonismo e agonismo à distância”, respectivamente para as espécies patogénicas e micorrízicas. Neste processo parecem intervir enzimas líticas, como a amilase, celulase, lacase e lipase, produzidas pelo H. fasciculare. Observaram-se ainda alterações morfológicas no H. fasciculare possivelmente com o intuito de se tornar mais resistente à invasão da espécie interactuante e/ou mais invasivo. Pelo contrário...

Identificação de proteínas secretadas por duas espécies de Leptospira, uma patogênica e uma saprófita.; Identification of secreted proteins of two species of Leptospira, one pathogenic and one saprophyte.

Ricardi, Ligia Maria Piassi
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/03/2013 PT
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A leptospirose é uma zoonose de distribuição mundial causada por espiroquetas patogênicas do gênero Leptospira. Resultados experimentais demonstraram que a patogênese pode estar relacionada com a capacidade destas bactérias em aderir a proteínas da matriz extracelular, escapar da resposta imune do hospedeiro e de produzir toxinas. Este trabalho teve como objetivo identificar proteínas secretadas por Leptospira interrogans sorovar Pomona estirpe Fromm kennewicki (patogênica) e Leptospira biflexa sorovar Patoc estirpe Patoc I (saprófita), através de análise proteômica. As leptospiras foram cultivadas em meio EMJH suplementado com soro de coelho ou albumina bovina. Os sobrenadantes foram filtrados, dialisados e liofilizados para aplicação das tecnologias de análise proteômica utilizando gel bidimensional e análise em solução. A análise dos peptídeos obtidos, nos dois procedimentos, foi realizada utilizando-se LC/MS/MS. Foi possível a identificação de 159 proteínas diferentes nas amostras de L.interrogans, entre as quais 64 foram positivas em pelo menos uma das ferramentas usadas para a predição. Em L. biflexa, 104 proteínas diferentes foram identificadas, entre elas 43 proteínas foram positivas pela análise in silico. Entre as proteínas identificadas...

Relação patógeno-hospedeiro : análise bioquímica e proteômica da interação do fungo Metarhizium anisopliae e seus hospedeiros artrópodes

Santi, Lucélia
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
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O fungo filamentoso Metarhizium anisopliae é um patógeno capaz de infectar uma grande variedade de artrópodes. A identificação de proteínas e atividades enzimáticas que participem ativamente do processo de infecção é um importante alvo de estudo. Com o objetivo de identificar tais proteínas, uma nova estratégia foi utilizada: imunoproteômica. Estudos relacionados à produção de esporos, formulação e infectividade de M. anisopliae para o controle de Dysdercus peruvianus (Hemiptera: Pyrrhocoridae) foram também realizados. Formulações contendo 10% de óleo de soja adicionado a 108 conídio.mL-¹ foi a mais efetiva para ninfas e adultos, sendo as ninfas mais sensíveis ao fungo. Analisando as proteínas extraídas da superfície do esporo, foram identificadas atividades relacionadas à proteção, nutrição e patogenicidade do fungo, como proteases, quitinases, lipases, fosfolipase C (identificada pela primeira vez em esporos), trealase e enzimas envolvidas na proteção contra espécies reativas de oxigênio. Utilizando a metodologia de imunoproteômica diferencial, foram observadas diferenças na secreção de proteínas de M. anisopliae em relação aos dois hospedeiros testados: D. peruvianus e Rhipicephalus microplus (Acari: Ixodidae). Foram identificadas proteases...

Estresse oxidativo em clones de seringueira sob ataque de antracnose-das-folhas

Fiori, Maíra dos Santos
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: xii, 83 f. : il. color., gráfs., tabs.
POR
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Pós-graduação em Ciência Florestal - FCA; As plantas defendem-se continuamente contra ataques de bactérias, vírus, fungos, invertebrados e outras plantas. O estresse oxidativo é um tipo de resposta fisiológica da planta após o reconhecimento do patógeno, podendo resultar em sintomas diversos, dependendo da sensibilidade, e dos mecanismos de defesa da planta hospedira. Situações de estresse impostas por diversos fatores, como de estresse biótico, que resulta da ação de micro-organismos patogênicos, nematóides e artrópodes e de interações simbióticas bactéria/cianobactéria/fungoplanta, são de enorme relevância para o crescimento, desenvolvimento, produtividade e sobrevivência dos hospedeiros. A antracnose causada por Colletotrichum gloeosporoides, constitui um sério problema para a cultura da seringueira [Hevea brasiliensis (Willd. Ex Adr. De Juss) Müell. Arg.] no Estado de São Paulo. Este fungo ataca diversas partes da planta ou atua como saprófita associado a outros patógenos, prejudicando o crescimento, desenvolvimento e a produtividade. Foram analisadas alterações bioquímicas em folhas de mudas de três clones de seringueira RRIM 600, GT1 e PR255 infectadas pelo fungo C. gloeosporoides, observando os indicadores de estresse oxidativo (lipoperóxidos...

A unique endoglucanase-encoding gene cloned from the phytopathogenic fungus Macrophomina phaseolina.

Wang, H; Jones, R W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1995 EN
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The deduced amino acid sequence derived from a Macrophomina phaseolina beta-1,4-endoglucanase-encoding gene revealed 48% identity (over 119 amino acids) with egl1 from the phytopathogen Pseudomonas solanacearum. Its similarity to saprophyte endoglucanases was not significant. Its minimum substrate size, unlike that of any known saprophyte endoglucanase, was cellopentaose. The unique characteristics of M. phaseolina egl1-encoded endoglucanase suggest that it is phytopathogen specific.

Pathogenesis of tuberculosis in mice exposed to low and high doses of an environmental mycobacterial saprophyte before infection.

Hernandez-Pando, R; Pavön, L; Arriaga, K; Orozco, H; Madrid-Marina, V; Rook, G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1997 EN
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Mycobacteria are ubiquitous in the environment, but they are not part of the normal human microbial flora. It has been suggested that variable contact with mycobacteria can influence susceptibility to mycobacterial pathogens and the efficacy of subsequent Mycobacterium bovis BCG vaccination. To test this, mice were immunized with high or low doses of an environmental saprophyte, M. vaccae, that is intensely immunogenic as an autoclaved preparation. Two months later, they received an intratracheal challenge with M. tuberculosis H37Rv. Recipients of a low Th1-inducing dose (10(7) organisms) were partially protected and maintained a high ratio of interleukin 2 (IL-2)-positive to IL-4-positive cells in the perivascular, peribronchial, and granulomatous areas of the lung, whereas in unimmunized controls the IL-4-positive cells increased markedly between days 21 and 28. In contrast, recipients of the high dose (10(9) organisms), which primes Th2 as well as Th1 cytokine production, died more rapidly than unimmunized controls and showed massive pneumonia from day 7. The ratio of IL-2-positive to IL-4-positive cells in all compartments of the lung rapidly fell to 1 by day 14 for these animals. These events correlated with cytokine mRNA profiles and with increases in the local toxicity of tumor necrosis factor alpha (TNF-alpha)...

MYCOPLASMA INOCUUM SP. N., A SAPROPHYTE FROM CHICKENS

Adler, H. E.; Shifrine, M.; Ortmayer, Herrad
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1961 EN
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Adler, H. E. (University of California, Davis), M. Shifrine, and Herrad Ortmayer. Mycoplasma inocuum sp. n., a saprophyte from chickens. J. Bacteriol. 82:239–240. 1961.—A new species of Mycoplasma was isolated from the infraorbital sinuses of chickens. The organism, a saprophyte, differs from all known mycoplasmas of avian origin. A description of this isolate is given. It has been named Mycoplasma inocuum sp. n.

Utilization of Amino Acids During Growth of Mycobacterium tuberculosis in Rotary Cultures

Lyon, Richard H.; Hall, Wendell H.; Costas-Martinez, Carlos
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1970 EN
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Marked differences were observed in the response of actively growing cells of the saprophyte, Mycobacterium smegmatis 607, and the avirulent human strain, M. tuberculosis (H37Ra), to several different nitrogen sources in aerated (rotary) cultures. The growth-promoting effect and utilization of equimolar concentrations (5 μmoles/ml) of l-alanine, l-aspartic acid, monosodium glutamate, or ammonium chloride were compared with that of l-asparagine, the normal nitrogen source, in Sauton synthetic liquid medium. The saprophyte grew equally well with each nitrogen source. However, marked differences were seen with H37Ra. Based on the rate of growth and cell yield, the relative growth-promoting effect of the amino acids for H37Ra is: alanine ≫ glutamate > asparagine > aspartic. Utilization of alanine, glutamate, and aspartic correlated well with growth. In contrast, utilization of asparagine during early growth of H37Ra was severalfold greater than that of either alanine or glutamate. Extracellular amino acids accumulated during the metabolism of asparagine but not during the utilization of the other nitrogen sources. Balanced metabolism of asparagine does not take place during aerated growth of H37Ra in asparagine media. During the metabolism of l-asparagine by M. tuberculosis (H37Ra) in aerated liquid cultures...

Staphylococci in Competition1: III. Influence of pH and Salt on Staphylococcal Growth in Mixed Populations

Peterson, A. C.; Black, J. J.; Gunderson, M. F.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1964 EN
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Previous results showed definite repressive effects on the growth of staphylococci in mixed cultures due to the competitive growth of psychrophilic saprophytes. This study was continued, and the influence of other environmental factors, pH and salt, on the competition between staphylococci and saprophytes was investigated. Initial pH values varied from 5 to 9. At the extremes of the pH range, staphylococci failed to grow, while the saprophytes grew under all of the conditions tested. At pH 5, the growth curves for the saprophytes were markedly altered from those obtained at neutral pH. The lag phases were greatly lengthened at and below 20 C, but normal numbers of saprophytes were reached in the stationary phase. At pH 6 and 8, staphylococcal growth showed the same inhibition observed at pH 7, at and below 20 C; normal multiplication was observed above this temperature, but with accelerated death phases. Thus, pH did not primarily effect staphylococcal growth through its influence on saprophyte growth and competition, but rather directly affected the growth of Staphylococcus cultures. Salt concentrations from 3.5 to 9.5% were investigated for influence on staphylococcal growth in mixed populations. Above 3.5% salt, staphylococcal inhibition at and above 20 C was not as marked as in the controls...

Staphylococci in Competition1: IV. Effect of Starch and Kind and Concentration of Sugar on Staphylococcal Growth in Mixed Populations

Peterson, A. C.; Black, J. J.; Gunderson, M. F.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1964 EN
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Foods containing large amounts of carbohydrate have frequently been involved in staphylococcal food poisoning. Custard has been considered to be a highly favorable culture medium for staphylococci; however, it may be a selective medium rather than an ideal one. The influence of dextrose, lactose, and sucrose in varying amounts from 0.25 to 18%, and of starch, on the growth of staphylococci in mixed populations with saprophytes was determined. The inhibitory effect of the sugars was much greater on the saprophyte population than on the staphylococci. Of the three sugars, sucrose was most inhibitory to the saprophytes. It greatly decreased their lag periods as the concentration of sugar increased. Dextrose was the least inhibitory; in fact, 0.5% dextrose gave considerable stimulus to saprophyte growth. This sharply repressed staphylococcal growth. Lactose occupied an intermediate position. Rapid onset of the death phase of the staphylococci was observed in all increased sugar concentrations and seemed to be a pH effect rather than a result of competition. Sucrose exerted an inhibitory effect on the growth of saprophytes at and above room temperature. In the presence of 2.5% corn starch, staphylococcal growth in mixed cultures was slightly inhibited...

Comparative and Functional Genomic Analyses of Iron Transport and Regulation in Leptospira spp.▿ †

Louvel, H.; Bommezzadri, S.; Zidane, N.; Boursaux-Eude, C.; Creno, S.; Magnier, A.; Rouy, Z.; Médigue, C.; Girons, I. Saint; Bouchier, C.; Picardeau, M.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
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The spirochetes of the Leptospira genus contain saprophytic and pathogenic members, the latter being responsible for leptospirosis. Despite the recent sequencing of the genome of the pathogen L. interrogans, the slow growth of these bacteria, their virulence in humans, and a lack of genetic tools make it difficult to work with these pathogens. In contrast, the development of numerous genetic tools for the saprophyte L. biflexa enables its use as a model bacterium. Leptospira spp. require iron for growth. In this work, we show that Leptospira spp. can acquire iron from different sources, including siderophores. A comparative genome analysis of iron uptake systems and their regulation in the saprophyte L. biflexa and the pathogen L. interrogans is presented in this study. Our data indicated that, for instance, L. biflexa and L. interrogans contain 8 and 12 genes, respectively, whose products share homology with proteins that have been shown to be TonB-dependent receptors. We show that some genes involved in iron uptake were differentially expressed in response to iron. In addition, we were able to disrupt several putative genes involved in iron acquisition systems or iron regulation in L. biflexa. Comparative genomics, in combination with gene inactivation...

Listeria monocytogenes — from saprophyte to intracellular pathogen

Freitag, Nancy E.; Port, Gary C.; Miner, Maurine D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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Listeria monocytogenes is a bacterium that lives in the soil as a saprophyte but is capable of making the transition into a pathogen following its ingestion by susceptible humans or animals. Recent studies suggest that L. monocytogenes mediates its saprophyte-to-cytosolic-parasite transition through the careful modulation of the activity of a virulence regulatory protein known as PrfA, using a range of environmental cues that include available carbon sources. In this Progress article we describe the regulation of PrfA and its role in the L. monocytogenes transition from the saprophytic stage to the virulent intracellular stage.

Transcription Factor Amr1 Induces Melanin Biosynthesis and Suppresses Virulence in Alternaria brassicicola

Cho, Yangrae; Srivastava, Akhil; Ohm, Robin A.; Lawrence, Christopher B.; Wang, Koon-Hui; Grigoriev, Igor V.; Marahatta, Sharadchandra P.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
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Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC) were nonpathogenic and another gene (AbVf8) caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of Δamr1 and characterized their phenotypes. The Δamr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway...

A complex gene locus enables xyloglucan utilization in the model saprophyte Cellvibrio japonicus

Larsbrink, Johan; Thompson, Andrew J; Lundqvist, Magnus; Gardner, Jeffrey G; Davies, Gideon J; Brumer, Harry
Fonte: BlackWell Publishing Ltd Publicador: BlackWell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
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The degradation of plant biomass by saprophytes is an ecologically important part of the global carbon cycle, which has also inspired a vast diversity of industrial enzyme applications. The xyloglucans (XyGs) constitute a family of ubiquitous and abundant plant cell wall polysaccharides, yet the enzymology of XyG saccharification is poorly studied. Here, we present the identification and molecular characterization of a complex genetic locus that is required for xyloglucan utilization by the model saprophyte Cellvibrio japonicus. In harness, transcriptomics, reverse genetics, enzyme kinetics, and structural biology indicate that the encoded cohort of an α-xylosidase, a β-galactosidase, and an α-l-fucosidase is specifically adapted for efficient, concerted saccharification of dicot (fucogalacto)xyloglucan oligosaccharides following import into the periplasm via an associated TonB-dependent receptor. The data support a biological model of xyloglucan degradation by C. japonicus with striking similarities – and notable differences – to the complex polysaccharide utilization loci of the Bacteroidetes.

The pathogenicity for honey-bee larvae of microorganisms associated with european foulbrood

Bailey, L.
Fonte: INRA - Instituto Nacional de Investigação Agronômica da França Publicador: INRA - Instituto Nacional de Investigação Agronômica da França
Tipo: Journal Article-postprint
EN; ENGLISH
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Tests made on larvae in normal bee colonies with pure cultures of Streptococcus pluton (White), Streptococcus faecalis Andrews and Horder, and Bacillus alvei Cheshire and Cheyne, three bacterial species commonly associated with European foulbrood (EFB), showed that S. pluton was the natural prirnary etiological agent. These results, together with other recent work, indicate that S. pluton is the cause of EFB throughout the world. Of the other associated bacterial species, Bacterium eurydice White, which is the most commnon, and S. faecalis probably have supplementary pathogenic effects. Bacillus alvei and other less common bacilli are saprophytes of the dead larvae.

Identification de composés naturels contre Saprolegnia sp., un champignon pathogène en aquaculture

Faille, Arianne
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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La saprolégniose est une maladie fongique causée par le champignon aquatique Saprolegnia sp. qui affecte les poissons sauvages et ceux provenant des piscicultures. L’apparition de touffes cotonneuses semblables à de la ouate de couleur blanche à grise est souvent la première indication de l’infection. Ce saprophyte ubiquitaire se nourrit habituellement des œufs de poissons morts, mais peut se propager rapidement aux œufs sains causant la mort de ces derniers. La saprolégniose est souvent une infection secondaire, mais des souches virulentes peuvent facilement se développer sur les salmonidés ayant subi un stress ou une mauvaise manipulation. De grandes pertes économiques associées à la saprolégniose sont rapportées chaque année à travers le monde surtout dans l’industrie de la pisciculture. Jusqu’en 2002, le contrôle de la saprolégniose pouvait se faire par l’utilisation du vert de malachite, un colorant organique ayant une grande activité antifongique. Malheureusement, cette molécule a été bannie à cause de ses propriétés cancérigènes. Aucun composé aussi efficace n’est actuellement disponible pour traiter les infections de la saprolégniose. Des molécules ou extraits naturels ayant un potentiel antifongique ont donc été testés à l’aide de deux techniques (par graines de chanvre et par cylindre d’agar). Les molécules d’un extrait de propolis (cire de ruches d’abeilles) démontrant de l’activité anti-Saprolegnia ont été identifiées. De plus...

Invasive pulmonary aspergillosis.; Aspergilose pulmonar invasiva.

Peixinho, P; Serviço de Medicina 2, Hospital de Curry Cabral, Lisboa.; Sabino, T; Duarte, C; Cruz, T; Bragança, N
Fonte: Ordem dos Médicos Publicador: Ordem dos Médicos
Tipo: info:eu-repo/semantics/article; article; article; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em 30/04/2003 POR
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Aspergillosis, the most frequent of pulmonary mycosis, represents a group of varying pathogenesis diseases with the same etiological agent--Aspergillus. This fungus is a saprophyte of normal respiratory airways, but the disease occurs in immunocompromised hosts. There are several anatomo-clinical forms, but it is important to know that some could be fatal, being necessary an early diagnosis and therapy. The authors describe an Invasive Pulmonary Aspegillosis case, in a immunocompromised patient submitted to long term corticotherapy treatment. Was started with liposomal Amphotericin B, discontinued due to nephrotoxicity and substituted by Itraconazol, with clinical, laboratorial and radiologic favourable evolution, as it's proven by imagiological studies.; Aspergillosis, the most frequent of pulmonary mycosis, represents a group of varying pathogenesis diseases with the same etiological agent--Aspergillus. This fungus is a saprophyte of normal respiratory airways, but the disease occurs in immunocompromised hosts. There are several anatomo-clinical forms, but it is important to know that some could be fatal, being necessary an early diagnosis and therapy. The authors describe an Invasive Pulmonary Aspegillosis case, in a immunocompromised patient submitted to long term corticotherapy treatment. Was started with liposomal Amphotericin B...

Inhibition du pathogène des salmonidés Saprolegnia parasitica par des bactéries aquatiques

Domingue Gauthier, Vincent
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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Les maladies constituent présentement la cause la plus importante de perte économique en aquaculture moderne. Chez certaines espèces, notamment les salmonidés (Oncorhynchus sp. et Salmo sp.), on rapporte des pertes annuelles atteignant cinquante pour cent de la production. À l’heure actuelle, les infections fongiques occupent le second rang derrière les maladies bactériennes en fonction de leur importance économique. Ces poissons sont particulièrement vulnérables à une infection fongique causée par Saprolegnia sp. qui infecte habituellement les oeufs morts. Le saprophyte ubiquitaire se propage ensuite aux oeufs sains et aux individus matures. Malheureusement, le traitement efficace de cette infection, souvent primaire et parfois secondaire, est de plus en plus difficile en raison de nouvelles réglementations restrictives entourant le vert de malachite. Jadis, ce colorant constituait le fongicide le plus efficace dans la lutte contre la saprolégniose, mais son potentiel cancérigène en limite maintenant l’utilisation. Jusqu'à présent, aucun traitement disponible n’est aussi efficace que le vert de malachite pour le contrôle de la saprolégniose. Récemment, nous sommes parvenus à isoler trois bactéries capables d’inhiber la croissance de Saprolegnia sp. in vitro. Ces trois Pseudomonas fluorescens proviennent d’une pisciculture dans laquelle survenaient des cas d’infections à Saprolegnia parasitica. En poussant la caractérisation de l’activité grâce à des analyses de chromatographie liquide haute performance et de spectrométrie de masse...

A FURTHER NOTE UPON THE EXPERIMENTAL PRODUCTION OF LEPROSY IN THE MONKEY (MACACUS RHESUS), WITH A CRITICAL STUDY OF THE CULTURE EMPLOYED

Duval, Charles W.; Couret, Maurice
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/03/1912 EN
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Fatal leprosy, with all its clinical and pathological manifestations in man, may be experimentally induced in the monkey (Macacus rhesus) with a pure culture of the acid-fast bacillus cultivated by one of us (Duval) from a leprous lesion in man. To produce the disease experimentally, it seems necessary to give the animal repeated injections of large numbers of leprosy bacilli at given intervals for a period of months. That the infection is more likely to follow where sensitization is first established is definitely proven by the specific experiments that we have carried out upon a variety of laboratory animals. The first injection, we assume, sensitizes the animal and may consist of either killed or viable lepra bacilli. The necessity of first sensitizing the monkey and then giving repeated doses of viable organisms over a long period might explain the relative infrequency of the disease in man; at least, it offers an explanation of the fact that man rarely, if ever, contracts leprosy, although intimately associated for an indefinite period with those afflicted with the disease. The leprous lesions in the monkey are histologically indistinguishable from those in man and do not essentially resemble the specific lesion of tuberculosis...

The dynamics of apoplast phenolics in tobacco leaves following inoculation with bacteria

Baker, Con J.; Mock, Norton M.; Smith, Jodi M.; Aver'yanov, Andrey A.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 20/08/2015 EN
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This study demonstrates that the accumulation of apoplastic phenolics is stimulated in planta in response to bacterial inoculation. Past studies have shown that levels of extracellular phenolics are elicited in plant cell suspensions in response to bacteria, and that tomato plants infected with viroids showed changes in apoplastic phenolics. The method described here monitored changes in apoplastic phenolics in tobacco leaves following bacterial inoculation of the same tissue. Inoculation with a saprophyte, Pseudomonas fluorescens, which does not cause visible symptoms or physical damage, was used to elicit phenolics and examine the effects of variable parameters on phenolic composition. Location of the inoculation on the leaf, position, or developmental age of the leaf on the plant, and inoculum concentration were standardized for further experiments. The patterns of phenolic change in the apoplast were compared for tobacco inoculated with P. syringae pathovars, pv. syringae, which causes a resistant HR reaction within 15 h, and pv. tabaci, which causes a susceptible reaction with delayed visible symptoms. Both pathogens elicited lower increased levels of acetosyringone compared to the saprophyte, P. fluorescens but had greatly increased levels of the chlorogenic acid derivatives. The latter metabolites appear to have come from the intracellular stores...