Wanderley de Souza

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Epimastigote forms of the pathogenic parasite Trypanosoma cruzi were used to study the endocytic process in a protozoon. These elongated unicellular organisms are highly polarized cells: endocytosis occurs only at the anterior region through the cytostome and the flagellar pocket membrane, areas of the plasma membrane where the cell cytoskeleton, formed by(More)
A major ceramide monohexoside (CMH) was purified from lipidic extracts of Cryptococcus neoformans. This molecule was analyzed by high-performance thin-layer chromatography (HPTLC), gas chromatography coupled with mass spectrometry, and fast atom bombardment-mass spectrometry. The cryptococcal CMH is a beta-glucosylceramide, with the carbohydrate residue(More)
The survival of a eukaryotic protozoan as an obligate parasite in the interior of a eukaryotic host cell implies its adaptation to an environment with a very different ionic composition from that of its extracellular habitat. This is particularly important in the case of Ca2+, the intracellular concentration of which is 3 orders of magnitude lower than the(More)
The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we(More)
A monospecific polyclonal antibody obtained against a cysteine proteinase isolated from epimastigotes of Trypanosoma cruzi was used for the immunocytochemical localization of the protein by electron microscopy and to analyse the role played by cysteine proteinase in the process of T. cruzi-host cell interaction. Cytoplasmic structures that correspond to(More)
a Departamento de Bioquı́mica Médica, Uni6ersidade Federal do Rio de Janeiro, Cidade Uni6ersitária, 21941-590, Rio de Janeiro, RJ, Brazil b Di6isão de Quı́mica, Setor de Quı́mica Orgânica, CENPES, Petrobrás, Cidade Uni6ersitária, 21949-900, Rio de Janeiro, RJ, Brazil c Centro de Biociências e Biotecnologia, Uni6ersidade Estadual do Norte Fluminense, Campos(More)
The paper reviews basic aspects of the biology of Trypanosoma cruzi emphasizing the following topics: (a) developmental stages of the life cycle in the vertebrate and invertebrate hosts; (b) the cytoskeleton of the protozoan, especially the sub-pellicular microtubules; (c) the flagellum, emphasizing its attachment to the protozoan body through specialized(More)
In this work, we describe the ability of living cells of Entamoeba histolytica to hydrolyze extracellular ATP. In these intact parasites, whose viability was determined by motility and by the eosin method, ATP hydrolysis was low in the absence of any divalent metal (78 nmol P(i)/h/10(5) cells). Interestingly, in the presence of 5 mM MgCl(2) an ecto-ATPase(More)
Malaria parasites digest haemoglobin and detoxify the free haem by its sequestration into an insoluble dark-brown pigment known as haemozoin (Hz). Until recently, this pigment could be found only in Plasmodium parasites. However, we have shown that Hz is also present in the midgut of the blood-sucking insect Rhodnius prolixus [Oliveira et al. (1999) Nature(More)