Abstract

The kinetoplast is a concatenated network of complex mitochondrial DNA comprising of two different structures, known as minicircles and maxicircles. T. evansi molecular studies have revealed the complete loss of the maxicircles, while T. equiperdum has retained maxicircle fragments. The presence or absence of kinetoplast has been used for comparative studies of trypanosomes from different geographical areas. In this study was analyzed this ultrastructure by transmission electron microscopy of five trypanosoma isolates from two states of Venezuelan plains. T. evansi and T. equiperdum isolates blood samples previously cryopreserved from natural hosts of three horses, one donkey and one capybara (asymptomatic), were employed to induce experimental infections and expand in rats, then parasites were purified by ion exchange chromatography. These parasite sediments were chemically fixed in suspension. Samples were washed and included in agar, then were exposed to an increasing series of ethanol dehydration and included in Polybed epoxy resin. Sections of 60 nm were placed on copper grids with a collodion-carbon film for positive contrasting. Images were obtained and analyzed by observation in a transmission electron microscope. The photomicrographs shown as expected the integrity of kinetoplast in the five trypanosoma isolates studied, revealed the mitochondrial membrane covering the kinetoplast, which is exhibited in a disk form near the flagelar pocket and adjacent to the base of the flagellum. The kinetoplast's ultrastructures of Venezuelan trypanosoma isolates studied were equivalent to Colombian/ Chinese T. evansi and Chinese T. equiperdum isolates, but different to akinetoplastic natural ultrastructures of Brazilian T. evansi isolates.