Navegando por Palavras-chave "yeast"

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    Biological activity of Cryptococcus neoformans and Cryptococcus gattii from clinical and environmental isolates
    (Sociedade Brasileira de Patologia ClínicaSociedade Brasileira de PatologiaSociedade Brasileira de Citopatologia, 2013-06-01) Barbosa Junior, Antonio Marcio; Santos, Bruno Fernandes De Oliveira [UNIFESP]; Carvalho, Erick De Oliveira; Mélo, Dângelly Lins Figuerôa Martins De; Trindade, Rita De Cássia; Stoianoff, Maria Aparecida De Resende; Universidade Federal de Sergipe; Universidade Federal de São Paulo (UNIFESP); Instituto Dante Pazzanese; UFSE Applied Microbiology Laboratory; UFMG Mycology Laboratory
    INTRODUCTION: Cryptococcus neoformans and Cryptococcus gattii are encapsulated basidiomycetous yeasts with worldwide distribution. They cause cryptococcosis with features of systemic infection, affecting the central nervous system, lungs and skin in humans and animals. These fungi present numerous virulence factors that allow them to invade the host and multiply, among which extracellular enzyme capacity and microbial adaptation to different temperatures are worth mentioning. OBJECTIVE: To evaluate the production of protease and investigate possible differences in thermotolerance and urease activity in clinical and environmental yeast isolates. MATERIAL AND METHODS: Culture methods and Pz analysis were applied to assess urease and protease, whereas the optical density method was used to analyze biological activity in thermotolerance. RESULTS: There was no significant results as to microbial growth at the tested temperatures (25º, 37º and 42ºC). It was observed that clinical specimens grew better than environmental ones at elevated temperatures. As to C. neoformans, the moderate production of urease enzyme prevailed in both clinical and environmental isolates within 24h or 48h. Moreover, there was significant production on the seventh day of reading. The best reading time for viewing protease production in both isolates and species was the seventh day: 96% clinical samples and 94% environmental isolates. CONCLUSION: Further studies are required in order to investigate the virulence factors of C. neoformans and C. gattii cerebrospinal isolates from patients with meningoencephalitis and environmental samples from Sergipe. Furthermore, a higher technical accuracy and statistical precision are indispensable.
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    Characterization of cerebrosides from the thermally dimorphic mycopathogen Histoplasma capsulatum: expression of 2-hydroxy fatty N-acyl (E)-Delta(3)-unsaturation correlates with the yeast-mycelium phase transition
    (Oxford Univ Press Inc, 2001-02-01) Toledo, Marcos Sergio de [UNIFESP]; Levery, SB; Suzuki, Erika [UNIFESP]; Straus, Anita Hilda [UNIFESP]; Takahashi, Helio Kiyoshi [UNIFESP]; Univ Georgia; Universidade Federal de São Paulo (UNIFESP)
    Cerebroside (monohexosylceramide) components were identified in neutral lipids extracted from both the yeast and mycelial forms of the thermally dimorphic mycopathogen Histoplasma capsulatum. the components were purified from both forms and their structures elucidated by 1- and 2-dimensional nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and low energy tandem collision-induced dissociation mass spectrometry (ESI-MS/CID-MS). Both components were characterized as beta -glucopyranosylceramides (GlcCers) containing (4E,8E)-9-methyl-4,8-sphingadienine as the long-chain base, attached to 18-carbon 2-hydroxy fatty N-acyl components. However, while the fatty acid of the yeast form GlcCer was virtually all N-2'-hydroxyoctadecanoate, the mycelium form GlcCer was characterized by almost exclusive expression of N-2'-hydroxy-(E)-Delta (3)-octadecenoate. These results suggest that the yeast-mycelium transition is accompanied by up-regulation of an as yet uncharacterized ceramide or cerebroside 2-hydroxy fatty N-acyl (E)-Delta (3)-desaturase activity. They also constitute further evidence for the existence of two distinct pathways for ceramide biosynthesis in fungi, since glycosylinositol phosphorylceramides (GIPCs), the other major class of fungal glycosphingolipids, are found with ceramides consisting of 4-hydroxysphinganine (phytosphingosine) and longer chain 2-hydroxy fatty acids, in addition to identification of the major glucocerebroside components, minor components (<5%) detectable by molecular weight differences in the ESI-MS profiles were also characterized by tandem ESI-MS/CID-MS analysis. These minor components were identified as variants differing in fatty acyl chain length, or the absence of the sphingoid 9-methyl group or (E)-(8)-unsaturation, and are hypothesized to be either biosynthetic intermediates or the result of imperfect chemical transformation by the enzymes responsible for these features. Possible implications of these findings with respect to chemotaxonomy, compartmentalization of fungal glycosphingolipid biosynthetic pathways, and regulation of morphological transitions in H.capsulatum and other dimorphic fungi are discussed.
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    Cloning and expression of a functionally active truncated N-glycosylated KSHVORF4/KCP/Kaposica in the methylotrophic yeast Pichia pastoris
    (New York Acad Sciences, 2005-01-01) Pereira, NAG; Juliano, M. A.; Carmona, A. K.; Sturrock, E. D.; Kotwal, G. J.; Lahiri, D. K.; Univ Cape Town; Universidade Federal de São Paulo (UNIFESP)
    Kaposi's sarcoma herpesvirus (KSHV) is a typical DNA virus that is associated with a number of proliferative diseases including Kaposi's sarcoma. the KSHV open reading frame (ORF) 4 encodes a complement regulatory protein (Kaposi complement control protein, KCP) that binds complement components and inhibits the complement-mediated lysis of cells infected by the virus, thus providing a strategy for evasion of the host complement system. Based on primary sequence analysis and comparison with other functionally and structurally similar proteins, oligonucleotide primers were designed to amplify by polymerase chain reaction (PCR) three regions of the predicted ORF 4 from human herpes virus-8 (HHV-8) DNA isolated from a primary effusion lymphoma cell line. the PCR products were inserted by ligation into the expression vector pPIC9 to generate three recombinant plasmids for heterologous expression in the yeast, Pichia pastoris, to produce separately the four N-terminal sushi domains (KCP-S, small), KCP protein lacking the putative transmembrane-binding domain (KCP-M, medium), and the full-length protein (KCP-F, full). Expression of the viral proteins was confirmed by SDSPAGE, immunologic detection, and Western blot analyses using a rabbit polyclonal antibody directed against a selected peptide region that is common to all three recombinant KCPs. KCP-S directly from expression media could inhibit complement-mediated lysis of sensitized sheep erythrocytes by approximately 60% in a hemolysis assay. This result confirms previous reports that recombinant KCP is twice as efficient in inhibiting the classic pathway-mediated lysis of erythrocytes than is the vaccinia virus complement control protein, which also contains four sushi domains.
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    Cytotoxic and genotoxic effects of megazol, an anti-Chagas' disease drug, assessed by different short-term tests
    (Elsevier B.V., 2002-12-01) Poli, P.; Mello, M. A. de; Buschini, A.; Mortara, R. A.; Albuquerque, C. N. de; Silva, S. da; Rossi, C.; Zucchi, TMAD; Univ Parma; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)
    Cyto- and genotoxicity induced by drugs can limit the dose and duration of treatment, can adversely affect patient quality of life, and may be life-threatening. Two drugs are currently being used for treatment of the acute phase of Chagas' disease and both have serious undesirable effects. in this research, cyto- and genotoxic activity of the nitroimidazole-tiadiazole derivative CL 64855 2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole (megazol), a promising alternative drug, was evaluated in vitro with different short-term tests: (a) induction of recombination events and mutation in the yeast Saccharomyces cerevisiae D7 strain, with and without induction of cytochrome P-450; DNA damage (single and double strand breaks, alkali-labile sites, etc.) by the Comet assay in different mammalian cells. S. cerevisiae did not show a significant increase of mutant and recombinant event frequency,,both with and without cytochrome P450. On the other hand, the cytochrome complex appeared to detoxify the drug with respect to cytotoxicity. Results in rat and mouse fresh leukocytes showed a dose-response relation of drug-induced DNA damage. Findings in treated VERO cells suggested a complex treatment time-DNA damage relationship and the possible induction of repair mechanisms. Furthermore, bleomycin effects were increased in rat cells by simultaneous administration of megazol. Megazol shows different biological activity in relation to cellular types and experimental conditions (with or without cytochrome P-450, short/long time of exposure, with or without other genotoxins), thus suggesting a modulation of effectiveness by different physiological/biochemical conditions of cells. the findings could be useful to evaluate new megazol-derived compounds and to assess the risks/benefits relationship for each drug. (C) 2002 Elsevier Science Inc. All rights reserved.
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    Dimorphic expression of cerebrosides in the mycopathogen Sporothrix schenckii
    (Lipid Research Inc, 2000-05-01) Toledo, Marcos S. [UNIFESP]; Levery, Steven B.; Straus, Anita H. [UNIFESP]; Takahashi, Helio K. [UNIFESP]; Univ Georgia; Universidade Federal de São Paulo (UNIFESP)
    Major neutral glycosphingolipid components were extracted from Sporothrix schenckii, a dimorphic fungus exhibiting a hyphal saprophytic phase and a yeast parasitic phase responsible for chronic mycotic infections in mammalian hosts. These components, one from the mycelial form and two from the yeast form, were purified and their structures were elucidated by H-1 nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and tandem ESI-MS/MS, All three were characterized as cerebrosides (monohexosylceramides) containing (4E, 8E)-9-methyl-4,8-sphingadienine as the long-chain base attached to N-2'-hydroxyoctadecanoate and N2'-hydroxy-(E)-Delta(3)-octadecenoate as the fatty acyl components. However, while the mycelial form expressed only beta-glucopyranosylceramide, the yeast form expressed both beta-gluco- and beta-galactopyranosylceramides in approximately equal amounts. In addition, while the glucosylceramides of both mycelial and yeast forms had similar proportions of saturated and (E)-Delta(3) unsaturated 2-hydroxy fatty acid, the galactocerebroside of the yeast form had significantly higher levels of (E)Delta(3) unsaturation. The differences in cerebroside hexose structure represent a novel type of glycosphingolipid dimorphism not previously reported in fungi, Possible implications of these findings with respect to regulation of morphological transitions in S, schenckii and other dimorphic fungi are discussed. Dimorphic expression of cerebrosides in the mycopathogen Sporothrix schenckii.
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    A Novel beta-Glucosidase from Sporidiobolus pararoseus: Characterization and Application in Winemaking
    (Wiley-Blackwell, 2011-09-01) Baffi, Milla Alves; Tobal, Thaise; Lago, Joao Henrique G. [UNIFESP]; Leite, Rodrigo S. R.; Boscolo, Mauricio; Gomes, Eleni; Da-Silva, Roberto; Universidade Federal de Uberlândia (UFU); Universidade Federal de São Paulo (UNIFESP); Univ Fed Grande Dourados UFGD; São Paulo State Univ UNESP
    For the first time, the production of an extracellular beta-glucosidase (Sp-beta-gl) by a Sporidiobolus pararoseus yeast strain is reported. the Sp-beta-gl activity was quantified, characterized, and assessed for its efficiency in releasing aroma-enhancing compounds in wines. the maximum enzymatic synthesis was after 72 h of growth in a complex media with 20 g/L of cellobiose. the optimal pH and temperature were 5.5 and at 50 degrees C, respectively. It showed a wide range of pH stability and exhibited quite high thermostability at low temperatures. in addition, this beta-glucosidase revealed tolerance to wine-associated inhibitory compounds (sugars and ethanol), showing suitable characteristics for all the stages of alcoholic fermentation. the hydrolysis of the glycosidic terpenes by Sp-beta-gl was studied by gas chromatography, and its ability to efficiently release free terpenols has been demonstrated. the concentrations of geraniol, linalool, alpha-terpineol, and nerol were significantly increased in treated wines. These results suggest the potential application of this new yeast beta-glucosidase as an aroma-enhancing enzyme in winemaking.