José Roberto Meyer-Fernandes

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Due to the growing importance of cellular signaling mediated by reactive oxygen species (ROS), proteins that are reversibly modulated by these reactant molecules are of high interest. In this context, protein kinases and phosphatases, which act coordinately in the regulation of signal transduction through the phosphorylation and dephosphorylation of target(More)
The interaction and survival of pathogens in hostile environments and in confrontation with host immune responses are important mechanisms for the establishment of infection. Ectophosphatases are enzymes localized at the plasma membrane of cells, and their active sites face the external medium rather than the cytoplasm. Once activated, these enzymes are(More)
Trypanosoma cruzi virulence factors include molecules expressed on the cell surface as well as those secreted or shed into the extracellular medium. Phosphatase activities modulate different aspects of T. cruzi infection, although no studies to date addressed the presence and activity of phosphatases in vesicles secreted by this parasite. Here, we(More)
The outdated idea that reactive oxygen species (ROS) are only dangerous products of cellular metabolism, causing toxic and mutagenic effects on cellular components, is being replaced by the view that ROS have several important functions in cell signaling. In aerobic organisms, ROS can be generated from different sources, including the mitochondrial electron(More)
Fasting or starvation of 1(st)- and 2(nd)-day fifth instar Manduca sexta larvae leads to rapid activation of fat body glycogen phosphorylase. Under feeding conditions, 21-29% of the phosphorylase was found in the active form. However, after only one hour of starvation, the active form increased to 55-65%. In larvae on the 3(rd)-day there was a slower(More)
Cellular metabolism depends on the appropriate concentration of intracellular inorganic phosphate (Pi). Pi starvation-responsive genes appear to be involved in multiple metabolic pathways, implying a complex Pi regulation system in microorganisms and plants. A group of enzymes is required for absorption and maintenance of adequate phosphate levels, which is(More)
A cell-wall-associated phosphatase in hyphae of Fonsecaea pedrosoi, a fungal pathogen causing chromoblastomycosis, was previously characterized by the authors. In the present work, the expression of an acidic ectophosphatase activity in F. pedrosoi conidial forms was investigated. The surface phosphatase activity in F. pedrosoi is associated with the cell(More)
Leishmania parasites, the causative agent of leishmaniasis, are transmitted through the bite of an infected sand fly. Leishmania parasites present two basic forms known as promastigote and amastigote which, respectively, parasitizes the vector and the mammalian hosts. Infection of the vertebrate host is dependent on the development, in the vector, of(More)
Trypanosoma cruzi, the protozoan responsible for Chagas disease, has a complex life cycle comprehending two distinct hosts and a series of morphological and functional transformations. Hemoglobin degradation inside the insect vector releases high amounts of heme, and this molecule is known to exert a number of physiological functions. Moreover, the absence(More)
Metarhizium anisopliae is an entomopathogenic fungus with the ability to infect a broad range of arthropods, and have evolved distinct strategies for their attachment to hosts. Here, we describe the characterisation of ecto-phosphatase activity on the conidia surface of M. anisopliae and its relevance in the host interaction process. Ecto-phosphatase(More)