共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
Almeida AJ Martins M Carmona JA Cano LE Restrepo A Leão C Rodrigues F 《Fungal genetics and biology : FG & B》2006,43(6):401-409
The present work focuses on the analysis of cell cycle progression of Paracoccidioides brasiliensis yeast cells under different environmental conditions. We optimized a flow cytometric technique for cell cycle profile analysis based on high resolution measurements of nuclear DNA. Exponentially growing cells in poor-defined or rich-complex nutritional environments showed an increased percentage of daughter cells in accordance with the fungus' multiple budding and high growth rate. During the stationary growth-phase cell cycle progression in rich-complex medium was characterized by an accumulation of cells with higher DNA content or pseudohyphae-like structures, whereas in poor-defined medium arrested cells mainly displayed two DNA contents. Furthermore, the fungicide benomyl induced an arrest of the cell cycle with accumulation of cells presenting high and varying DNA contents, consistent with this fungus' unique pattern of cellular division. Altogether, our findings seem to indicate that P. brasiliensis may possess alternative control mechanisms during cell growth to manage multiple budding and its multinucleate nature. 相似文献
4.
5.
6.
7.
8.
In its attempt to survive, the fungal cell can change the cell wall composition and/or structure in response to environmental stress. The molecules involved in these compensatory mechanisms are a possible target for the development of effective antifungal agents. In the thermodimorphic fungus Paracoccidioides brasiliensis Pb01, the main polymers that compose the cell wall are chitin and glucans. These polymers form a primary barrier that is responsible for the structural integrity and formation of the cell wall. In this study the behaviour of P. brasiliensis was evaluated under incubation with cell wall stressor agents such as Calcofluor White (CFW), Congo Red (CR), Sodium Dodecyl Sulphate (SDS), NaCl, KCl, and Sorbitol. Use of concentrations at which the fungus is visually sensitive to those agents helped to explain some of the adaptive mechanisms used by P. brasiliensis in response to cell wall stress. Our results show that 1,3-β-D-glucan synthase (PbFKS1), glucosamine-6-phosphate synthase (PbGFA1) and β-1,3-glucanosyltransferase (PbGEL3)as well as 1,3-β-D-glucan and N-acetylglucosamine (GlcNAc) residues in the cell wall are involved in compensatory mechanisms against cell wall damage. 相似文献
9.
Paracoccidioides brasiliensis causes one of the most prevalent systemic mycoses in Latin America--paracoccidioidomycosis. It is a dimorphic fungus that undergoes a complex transformation in vivo, with mycelia in the environment producing conidia, which probably act as infectious propagules upon inhalation into the lungs, where they transform to the pathogenic yeast form. This transition is readily induced in vitro by temperature changes, resulting in modulation of the composition of the cell wall. Notably, the polymer linkages change from beta-glucan to alpha-glucan, possibly to avoid beta-glucan triggering the inflammatory response. Mammalian oestrogens inhibit this transition, giving rise to a higher incidence of disease in males. Furthermore, the susceptibility of individuals to paracoccidioidomycosis has a genetic basis, which results in a depressed cellular immune response in susceptible patients; resistance is conferred by cytokine-stimulated granuloma formation and nitric oxide production. The latency period and persistence of the disease and the apparent lack of efficacy of humoral immunity are consistent with P. brasiliensis existing as a facultative intracellular pathogen. 相似文献
10.
Ladislao Pollak 《Mycopathologia》1971,45(3-4):217-219
In soil extract agar and in Bennett medium abundant aleuriospores ofParacoccidioides brasiliensis have been observed. The possibility that these spores could be the infecting elements for man is discussed.
Resumen Se han observado abundantes aleuriosporas deParacoccidioides brasiliensis en agar extracto de tierra y en medio de Bennett. Se discute la posibilidad de que éstas esporas puedan ser los elementos que infectan al hombre.相似文献
11.
Cell wall composition of the yeast and mycelial forms of Paracoccidioides brasiliensis 总被引:8,自引:7,他引:8 下载免费PDF全文
Isolation and chemical analyses of the cell walls of the yeast (Y form) and mycelial forms (M form) of Paracoccidioides brasiliensis and Blastomyces dermatitidis revealed that their chemical composition is similar and depends on the form. Lipids, chitin, glucans, and proteins are the main constituents of the cell walls of both forms of these fungi. There is no significant difference in the amount of lipids (5 to 10%) and glucans (36 to 47%) contained by the two forms. In both fungi, the Y form has a larger amount of chitin (37 to 48%) than the M form (7 to 18%), whereas the M form has a larger amount of proteins (24 to 41%) than the Y form (7 to 14%). Several properties of the glucan of P. brasiliensis were studied. Almost all of the glucan in the Y form was soluble in 1 n NaOH, was weakly positive in the periodic acid-Schiff reaction, was not hydrolyzed by snail digestive juice, and had alpha-glycosidic linkage. Glucans of the M form were divided into alkali-soluble (60 to 65%) and alkali-insoluble (35 to 40%) types. The alkali-soluble glucan was similar to that of the Y form; the alkali-insoluble glucan was positive in the periodic acid-Schiff reaction and was hydrolyzed by snail digestive juice. 相似文献
12.
13.
A Restrepo 《Sabouraudia》1985,23(5):323-334
Some aspects pertaining to the ecology of the dimorphic fungus, Paracoccidioides brasiliensis, are reviewed. The available facts concerning the interactions among the only known host (man), the environment (limited to certain Latin-American countries) and the parasite (with an unknown habitat), are analysed. Efforts are made to detect clue circumstances which may lead to discovery of the fungus micro-niche. An analysis of P. brasiliensis mycelial form reveals that such a form has the required capabilities to be the natural infectious form. Its requirements for a moist environment in vitro as well as the high relative humidity predominating in the heart of the endemic areas point towards the possibility of an aquatic--or at least, an extremely humid--habitat for P. brasiliensis. 相似文献
14.
Paracoccidioides brasiliensis is a pathogenic dimorphic fungus causing paracoccidioidomycosis, the most widespread systemic mycosis in Latin America. We have studied the structure of the alkali-extracted water-soluble cell wall polysaccharides (F1SS) from both mycelial and yeast phases of this fungus by using chemical analysis and NMR spectroscopic techniques. The F1SS polysaccharide from the mycelial phase consists of a trisaccharidic repeating unit of -->6)-[alpha-Galf -(1-->6)-alpha-Manp-(1-->2)]-alpha-Manp-(1-->. The F1SS polysaccharide of the yeast phase maintains 10% of the structure of the mycelium phase, but the main structure contain a disaccharide repeating unit of -->6)-[-alpha-Manp-(1-->2)]-alpha-Manp-(1-->, alternating with a trisaccharide repeating block of -->6)-[beta-Galf -(1-->6)-alpha-Manp-(1-->2)]-alpha-Manp-(1-->. 相似文献
15.
16.
M B De Albornoz 《Sabouraudia》1971,9(3):248-253
17.
Gioconda San-Blas Françoise Sorais Gustavo Niño-Vega Cioly Méndez Felipe San-Blas 《Current microbiology》1998,37(2):141-143
Cytosolic proteinases were assayed in both morphological phases of Paracoccidioides brasiliensis. Preparations from the mycelial phase were more active in vitro than those from the yeast cells. Optimal proteinase activities
for both phases occurred at pH's between 6.0 and 9.0, and at 45°C. Gelatin-SDS-PAGE electrophoresis separated several bands
(58–112 kDa) in mycelial preparations; a single band (70 kDa) was seen in yeast preparations. Enzymatic activities were inhibited
by antipain, phenyl methyl sulfonyl fluoride (PMSF), and chymostatin, suggestive of serine proteinases. Partial inhibition
of the mycelial enzymes by ethylene diamine tetraacetic acid (EDTA), 1,10-phenanthroline, and iodoacetamide, also suggested
the presence of cysteine- and metallo-proteinases. The enzymatic activity increased in preparations extracted from yeast cells
transforming to mycelia, and decreased in preparations obtained from the reverse process.
Received: 29 September 1997 / Accepted: 19 February 1998 相似文献
18.
Ayako Sano Reiko Tanaka Kazuko Nishimura Cilmery S. Kurokawa Kunie labuki R. Coelho Marcello Franco Mario Rubens Montenegro Makoto Miyaji 《Mycoscience》1997,38(2):117-122
We have studied the physiological and morphological features of 17 isolates ofParacoccidioides brasiliensis in order to define their phenotypes. The isolates were cultured at room temperature on potato dextrose agar (PDA, Difco)
slants for mycelial growth and in 1% dextrose brain heart infusion agar (BHIA, Difco) at 37°C for the study of yeast forms.
Most mycelial and yeast forms grew well between pH 5.6–9.4. In their response to osmotic pressure the isolates were separated
in three groups: intolerant, intermediate and tolerant. They also varied in carbohydrate assimilation tests, which indicated
important metabolic variation. No clear differences were observed in phenol oxidase tests, KNO3, starch, casein and arbutin assimilation tests. Only 1 of the isolates, Bt-19, had gelatinase activity. No correlation was
observed between the above differences and virulence. Two patterns of growth were observed in the mycelial cultures, glabrous
and cottonous, the latter being correlated with increased virulence for ddY mice. Most yeast forms grew as cerebriform colonies,
but Pb-HC and Bt-19 colonies had a cobblestone-like surface. 相似文献
19.