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The role of calcium in the invasion of the human erythrocyte by the parasitePlasmodium falciparum was studied. The intraerythrocytic and intraparasitic concentrations of Ca2+ were modified using calcium-ionophore A23187 and the chelator EGTA. The Ca2+ inside the parasite appared to be necessary for the normal completion of invasion. We determined that in(More)
The present study evaluates the expression of genes of Giardia lamblia, one of the most simple and most early diverging eukaryotes, that encode the metabolic enzymes pyruvate: ferredoxin oxidoreductase (PFOR), acetyl-CoA synthetase (ACS), alcohol dehydrogenase E (ADHE) and glutamate dehydrogenase (GDH) and the cyst wall protein (CWP1) gene in trophozoites,(More)
Giardia intestinalis is an intestinal parasite that has sparked considerable interest because of the public health problem it creates and because it is regarded as one of the earliest divergent eukaryotes. The present report describes a new method for quick, clean, and effective isolation of G. intestinalis cysts from fecal samples. The isolated cysts have(More)
Six myosins genes are now annotated in the Plasmodium falciparum Genome Project. Malaria myosins have been named alphabetically; accordingly, we refer to the two latest additions as Pfmyo-E and Pfmyo-F. Both new myosins contain regions characteristic of the functional motor domain of "true" myosins and, unusually for P. falciparum myosins, Pfmyo-F encodes(More)
Giardia intestinalis is a single-cell eukaryotic microorganism, regarded as one of the earliest divergent eukaryotes and thus an attractive model to study the evolution of regulatory systems. Giardia has two different forms throughout its life cycle, cyst and trophozoite, and changes from one to the other in response to environmental signals. The two(More)
The parasite Giardia intestinalis undergoes a differentiation process that allows it to infect its mammal host. That process is excystation. We examined the importance of protein phosphorylation during the passage from cyst to trophozoite. Cysts obtained from patients with giardiasis were excysted in vitro and the soluble cytoplasmic proteins were analyzed(More)
Calmodulin (CaM) is the primary sensor for calcium in the cell. It modulates various functions by activating CaM-binding proteins (CaMBPs). This study examined the calcium/CaM-dependent system in the ancient eukaryote Giardia intestinalis. A specific antibody against the parasite’s CaM was developed; this protein’s expression and location during different(More)
Giardia intestinalis is considered an early-branching eukaryote and is therefore a valuable model for studying primordial cellular processes. This work reports the characterization of the ubiquitin-activating enzyme (E1) during growth and different stages of trophozoite differentiation into cysts. We found that in Giardia E1 expression (both at mRNA and(More)
 Calcium is an important factor in the invasion of the erythrocyte by Plasmodium falciparum. We have proposed that the entrance of the cation into the erythrocyte might be a messenger that triggers a series of molecular events leading to invasion. Other authors have proposed that the site of action of the calcium is extracellular. We show herein that the(More)
INTRODUCTION Plasmodium falciparum is a highly polymorphic parasite, which allows it to evade the host's immune response, spread drug resistance and favours transmission. OBJECTIVES To analyse the genetic diversity of P. falciparum populations in samples from four endemic localities in Colombia. MATERIALS AND METHODS 123 blood samples were collected on(More)