The elemental composition of acidocalcisomes present in Trypanosoma cruzi bloodstream trypomastigotes was analyzed by X-ray microanalysis. Acidocalcisomes appear as electron-dense vesicles dispersed throughout the cytoplasm. X-ray microanalysis of whole cells adhered to Formvar-coated grids showed that they contained C, O, Na, Mg, P, S, Ca and Zn, although in some acidocalcisomes iron was also detected. However, in ultra-thin sections of parasites processed according to routine procedures, most elements were lost. Living parasites were incubated with gold-labeled holo-transferrin to test if the iron was taken up by receptor-mediated endocytosis. After incubation at 4 degrees C, labeling was observed only in the flagellar pocket membrane, showing that receptors to this protein are already present in bloodstream trypomastigotes. In parasites incubated at 28 degrees C no intracellular tracer was observed, despite the labeling in the flagellar pocket membrane. Our data show that some acidocalcisomes of T. cruzi bloodstream trypomastigotes contain iron and that this element was not taken up by receptor-mediated endocytosis.
The caspase-3-cleaved presence was evaluated in this study in the heart of irradiated rats, during the decline of ventricular function. Female Wistar rats were irradiated with a single dose of radiation (15 Gy) delivered directly to the heart and the molecular, histological and physiological evaluations were performed at thirteen months post-irradiation. The expressions of procollagen type I, TGF-ß1 and caspase-3-cleaved were analyzed using Western blotting. Cardiac structural and functional alterations were investigated by echocardiography and electron microscopy. In the irradiated group, the levels of procollagen type I, TGF-ß1 and caspase-3-cleaved are increased. Significant histological changes (degeneration of heart tissue and collagen deposition) and functional (reduced ejection fraction) were observed. Data suggest that the cardiac function decline after exposure to ionizing radiation is related, in part, to increased collagen and increased caspase-3-cleaved.
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