ABSTRACT
In Paracoccidioides brasiliensis, a dimorphic fungus pathogenic for humans, no significant differences were observed in the phospholipid species of both morphological phases. The species observed were phosphatidylcholine (PC, 30-40%), phosphatidylethanolamine (PE, 27-28%), phosphatidylserine (16-19%), phosphatidylinositol (13-17%) and sphingomyelin (3-5%). The main fatty acids found in the yeast (Y) phase were palmitate (56%), linoleate (18%) and oleate (15%), while linoleate predominated (61%) in the mycelial (M) phase, followed by palmitate (27%) and oleate (7%). In the Y phase the main free sterol was ergosta-5,22-dien-3 beta-ol (82%) plus some lanosterol (12%) and ergosterol (6%), while in the M phase, the latter predominated (88%), followed by low levels of ergosta-5,22-dien-3 beta-ol (12%). Ajoene [(E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide], a platelet aggregation inhibitor derived from garlic, induced alterations in phospholipid and fatty acid proportions such that PC was reduced to about 18% in both phases and PE increased to 38% (Y phase) or 44% (M phase), suggesting inhibition of PC synthesis. Ajoene also reduced saturated fatty acids (16:0 and 18:0) from 67 to 35% in the Y phase, with a corresponding increase in the unsaturated components. This effect was not seen in the M phase.
Subject(s)
Antifungal Agents/pharmacology , Disulfides/pharmacology , Paracoccidioides/drug effects , Phosphatidylcholines/biosynthesis , Plant Extracts/pharmacology , Fatty Acids/classification , Fatty Acids/metabolism , Paracoccidioides/growth & development , Paracoccidioides/metabolism , Paracoccidioides/ultrastructure , Phosphatidylcholines/classification , SulfoxidesABSTRACT
To quantify the dimorphic process in wild and mutant strains of Paracoccidioides brasiliensis, we defined a morphology index (Mi) in terms of the maximum cell length (l), maximum cell diameter (d), and septal diameter (s), according to the equation Mi = 2.13 + 1.13 log10 (ls/d2), whose intercept and slope were such that Mi was around 1 for yeast (spherical) cells or 4 for hyphal (elongated) cells. This discriminatory power was used to quantify morphological population mixtures through Mi histograms. During the temperature-induced dimorphic transition (either way), mean Mi (Mi) varied linearly with time, suggesting a continuity in the process. Also, in wild strains and mutants thereof we found an inverse relationship between Mi and content of both cell wall chitin and 1,3-alpha-glucan.
Subject(s)
Paracoccidioides/cytology , Paracoccidioides/growth & development , Cell Wall/chemistry , Chitin/analysis , Glucans/analysis , Morphogenesis , Mutation , Paracoccidioides/genetics , PhenotypeABSTRACT
Se exploró la existencia de factores citoplasmáticos que controlan la síntesis de glucán en Paracoccidioides brasiliensis. Se observó que el sistema estaba regulado por la presencia de proteinasas e inhibidores de proteinasas; diferentes según la fase levaduriforme o micelial del hongo. Con los datos obtenidos se complementa el modelo de dimorfismo en P. brasiliensis postulado anteriormente
Subject(s)
Paracoccidioides/cytologyABSTRACT
La sintesis de glucan in vitro partiendo de preparaciones particuladas de Paracoccidioides brasiliensis cepas IVIC Pb9 e IVIC Pb73 mostraram similitudes en cuanto a requirimientos ionicos, pH y buffer optimos, asi como en cuanto a la incorporacion de glucosa a partir de UDP-glucosa como nucleotido precursor preferencial para la sintesis de beta-glucan. Hubo diferencias en la eficiencia del sistema enzimatico, siendo las preparaciones particulares de la cepa IVIC Pb73. Se observo un efecto estimulador del sobrenadante citoplasmatico sobre la actividad de sintesis de las preparaciones de levaduras. Los resultados obtenidos permiten discutir algunas posibilidades sobre la regulacion de la sintesis de beta-glucan en P. brasiliensis
