In vitro effects of sodium selenite supplementation on cell viability of different forms of Trypanosoma cruzi

Selenium is an essential trace element which, at adequate levels, presents different beneficial biological effects, such as cancer regression, tissue development and protection against oxidative damage. The positive effects of this element are related to the expression of selenoproteins and their ability to modulate the immune system and the oxidative stress response. In Chagas disease and sleeping sickness, selenium supplementation has shown blood parasitism reduction and the alleviation of specific aspects of the diseases, such as diminishing anemia in sleeping sickness or minimization of myocardial and right ventricular chamber damage in Chagas disease. Although the influence of selenium in trypanosomiasis has been investigated, the direct effects of sodium selenite supplementation on trypanosome cells are poorly understood. Treatment of Trypanosoma cruzi cultures with low selenium doses demonstrated different results, according to the parasite evolutive form analyzed. Epimastigote cultures supplemented with 100 nM of sodium selenite presented cell growth increment, which varies from 10 to 40% according to the parasite strain assayed. Selenium concentration around 600nM leads to a 30% increase in the amastigote form number, whereas, at the same dose, the mammal host cell presented no cellular growth alteration. For the bloodstream form, the results agree with the literature, and all sodium selenite concentrations tested, demonstrated a reduction in parasite viability. The data suggest that selenium supplementation, under specific conditions, could increase T. cruzi viability, demonstrating that a strategy for using selenium as an adjuvant in Chagas disease treatment requires additional experimentation.

Trypanosoma cruzi: analysis of two different strains after piplartine treatment

ABSTRACT The hemoflagellate protozoan, Trypanosoma cruzi, mainly transmitted by triatomine insects through blood transfusion or from mother-to-child, causes Chagas' disease. This is a serious parasitic disease that occurs in Latin America, with considerable social and economic impact. Nifurtimox and benznidazole, drugs indicated for treating infected persons, are effective in the acute phase, but poorly effective during the chronic phase. Therefore, it is extremely urgent to find innovative chemotherapeutic agents and/or effective vaccines. Since piplartine has several biological activities, including trypanocidal activity, the present study aimed to evaluate it on two T. cruzi strains proteome. Considerable changes in the expression of some important enzymes involved in parasite protection against oxidative stress, such as tryparedoxin peroxidase (TXNPx) and methionine sulfoxide reductase (MSR) was observed in both strains. These findings suggest that blocking the expression of the two enzymes could be potential targets for therapeutic studies.

Satellyptus: analysis and database of microsatellites from ESTs of Eucalyptus

The main goal of our research was to search for SSRs in the Eucalyptus EST FORESTs database (using a software for mining SSR-motifs). With this objective, we created a database for cataloging Eucalyptus EST-derived SSRs, and developed a bioinformatics tool, named Satellyptus, for finding and analyzing microsatellites in the Eucalyptus EST database. The search for microsatellites in the FORESTs database containing 71,115 Eucalyptus EST sequences (52.09 Mb) revealed 20,530 SSRs in 15,621 ESTs. The SSR abundance detected on the Eucalyptus ESTs database (29% or one microsatellite every four sequences) is considered very high for plants. Amongst the categories of SSR motifs, the dimeric (37%) and trimeric ones (33%) predominated. The AG/CT motif was the most frequent (35.15%) followed by the trimeric CCG/CGG (12.81%). From a random sample of 1,217 sequences, 343 microsatellites in 265 SSR-containing sequences were identified. Approximately 48% of these ESTs containing microsatellites were homologous to proteins with known biological function. Most of the microsatellites detected in Eucalyptus ESTs were positioned at either the 5 or 3 end. Our next priority involves the design of flanking primers for codominant SSR loci, which could lead to the development of a set of microsatellite-based markers suitable for marker-assisted Eucalyptus breeding programs