In Brazil, the Trypanosoma sp. 858 was isolated from a toad (Anura: Bufonidae: Rhinella ictericus) and successfully maintained in cultures. We previously demonstrated that this trypanosome is different but tightly clustered phylogenetically with other trypanosomes from anurans. In this study, we addressed the ultrastructural features of cultured epimastigotes of this new trypanosome. Our results showed very long and thin free motile forms exhibiting a long flagellum and remarkable large and loose K-DNA network. In addition, the anterior portion contained many acidocalcisomes and a well-developed spongiome tubules-contractile vacuole system. One of the main morphological features of this anuran trypanosome was the presence of a complex cytostome-cytopharynx with a specialized membrane coating at the entrance, which is often hidden by the flagellum. Other conspicuous features are the presence of lipid-like droplets, lamellar membrane limited inclusions, and one very large reservosome, all at the posterior portion of the cell body. This new trypanosome may constitute an excellent model for organelles studies related to endocytosis and lipid storage, as demonstrated herein using scanning and transmission electron microscopy and three-dimensional models obtained by either electron microscopy tomography or dual-beam slice and view series.
Keywords: Anura; Cytostome-cytopharynx; K-DNA arrangement; Lipids; Organelle evolution; Reservosome; Trypanosoma.
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