Free and protein-linked glycoinositolphospholipids in Trypanosoma cruzi

Two glycoinositol phospholipids (GIPL A and GIPL B) have been purified from epimastigotes of Trypanosoma cruzi at the logarithmic phase of growth (2 days). The GIPLs differ mainly in the lipid moiety and are similar to the lipopeptidophosphoglycan (LPPG) previously isolated from epimastigotes at the stationary phase (4-5 days). [3H]-palmitic acid was incorporated into 1-O-hexadecyl-2-O-palmitoylglycerol in GIPL A and into a sphinganine ceramide with palmitic acid and lignoceric acid as the fatty acids in GIPL B. The lipids could be released by incubation with phosphatidylinositol-specific phospholipase C (PI-PLC) or glycosylphosphatidylinositol phospholipase D (GPI-PLD) from rat serum. The oligosaccharides share the common core structure of the glycosylphosphatidilinositol (GPI) membrane anchors. Microheterogeneity was demonstrated, as well as substitution by galactose, which is mainly in the furanose configuration as was previously described for the LPPG. However, methylation analysis indicated that 20 percent of the galactose is present as terminal pyranose units. In infective trypomastigotes, [3H]-palmitic acid was incorporated into the anchor of the Tc-85 glycoprotein. The lipid cleaved by phospholipase C digestion was identified as 1-O-hexadecylglycerol and the main oligosaccharide has the structure of the conserved core of all GPI anchors. [3H]-palmitic acid-labelled Tc-85 released into the culture medium as membrane vesicles showed 80 percent resistance to the action of PI-PLC. However, after mild alkaline hydrolysis, part of the radioactivity was released by the enzyme

Cinetica de incorporacion de glucosa y variacion morfologica del micelio de Ascobolus furfuraceus. / Kinetics of glucose uptake and morphological changes of the mycelium of Ascobulus furfuraceus

La cinetica de incorporacion de glucosa por el micelio de Ascobolus furfuraceus de 13 dias de crecimiento y realimentado con glucosa o con medio fresco total, esta en correlacion con la diferenciacion progresiva de estructuras vesiculares que funcionarian como reservorio de glucogeno

Accion de un polisacarido aislado del hongo Cyttaria johowii sobre el crecimiento del sarcoma 180 en ratones. / Effect of a polysaccharide isolated from the fungus Cyttaria johowii on the growth of sarcoma 180 in mice

Se estudio la actividad antitumoral de un polisacarido homogeneo obtenido del hongo Cyttaria johowii, a traves del efecto inhibitorio que produjo sobre el crecimiento del sarcoma 180 ascitico, inoculado por via intradermica o intraperitoneal en ratones endocriados de la cepa BALB/c. El polisacarido fue inoculado por via intraperitoneal durante 5 dias consecutivos comenzando 24 horas despues del inoculo tumoral. La dosis utilizada fue de 5 y 10 mg/kg raton/dia, para los grupos desafiados con sarcoma 180 intradermico y con sarcoma 180 intraperitoneal, respectivamente. Pudo observarse que el tratamiento con polisacarido produjo disminucion del crecimiento tumoral, maximo al 8o. dia tanto en los ratones inoculados con tumor por via id como ip. Ademas, se comprobo aumento del porcentaje de sobrevivientes y prolongacion de la media de dias de sobrevida, comparado con los animales tratados solo con tumor. Simultaneamente, fue analizada la accion del polisacarido sobre las poblaciones celulares de sangre periferica, observandose una disminucion significativa de linfocitos, maximo en el dia 15 en los ratones inoculados con sarcoma 180 ip, estas variaciones hematologicas no fueron observadas en los ratones desafiados con sarcoma 180 id. Ademas, se comprobo disminucion de la agregacion plaquetaria en los ratones con tumor tratados con polisacarido, respecto a los no tratados