Membrane-bound cysteine proteinase isoforms in different developmental stages of Trypanosoma cruzi.

Cysteine proteinase isoforms, immunologically cross-reactive with cruzipain and with a similar apparent molecular mass, have been identified in epimastigotes of Trypanosoma cruzi by extraction and phase partition using the detergent Triton X-114. These isoforms are concentrated in the microsomal fraction obtained after differential centrifugation, which is known to consist essentially of plasma membrane, can be labelled by incubation of live parasites with sulfo-NHS-biotin, and bind to cystatin-sepharose affinity columns. They are present, albeit with a different electrophoretic pattern, in the epimastigote, amastigote and trypomastigote stages of the parasite.Fil:Parussini, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

SUMOylation pathway in Trypanosoma cruzi: Functional characterization and proteomic analysis of target proteins

10.1074/mcp.M110.007369Molecular and Cellular Proteomics1012-MCPO

Trypanosoma cruzi: modification of alkaline phosphatase activity induced by trypomastigotes in cultured human placental villi Trypanosoma cruzi: alteração da atividade de fosfatase alcalina induzida por tripomastigotas em culturas de vilos placentários humanos

Human term placental villi cultured ''in vitro" were maintained with bloodstream forms of Trypanosoma cruzi during various periods of time. Two different concentrations of the parasite were employed. Controls contained no T. cruzi. The alkaline phosphatase activity was determined in placental villi by electron microscopy and its specific activity in the culture medium by biochemical methods. Results showed that the hemoflagellate produces a significant decrease in enzyme activity as shown by both ultracytochemical and specific activity studies and this activity was lower in cultures with high doses of parasites. The above results indicate that the reduction in enzyme activity coincides with the time of penetration and proliferation of T. cruzi in mammalian cells. These changes may represent an interaction between human trophoblast and T. cruzi.<br>Vilos placentários humanos a termo foram mantidos "in vitro" em interação com formas tripomastigotas sangüíneas de Trypanosoma cruzi, durante diversos períodos de tempo. Foram utilizadas concentrações diferentes de parasitas. Os controles não continham T. cruzi. Determinou-se a atividade de fosfatase alcalina em vilos placentários mediante microscopia eletrônica e sua atividade específica no meio de cultura, mediante métodos bioquímicos. Os resultados mostraram que o hemoflagelado produz uma diminuição significante da atividade enzimática tanto pelos estudos ultracitoquímicos como de atividade específica e esta atividade de fosfatase alcalina foi menor em culturas com altas doses de parasitas. Estes resultados são indicadores de que a redução de atividade enzimática coincide com o tempo de penetração e proliferação do T. cruzi nas células. Estas mudanças podem representar uma interação entre o trofoblasto humano e o T. cruzi

Simulating feedback and reversibility in substrate-enzyme reactions

We extend discrete event models (DEM) of substrate-enzyme reactions to include regulatory feedback and reversible reactions. Steady state as well as transient systems are modeled and validated against ordinary differential equation (ODE) models. The approach is exemplified in a model of the first steps of glycolysis with the most common regulatory mechanisms. We find that in glycolysis, feedback and reversibility together act as a significant damper on the stochastic variations of the intermediate products as well as for the stochastic variation of the transit times. This suggests that these feedbacks have evolved to control both the overall rate of, as well as stochastic fluctuations in, glycolysis

Classification and nomenclature of metacaspases and paracaspases: No more confusion with caspases.

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