New ultrastructural observations on the skeletal matrix of Tritrichomonas foetus
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Tritrichomonas foetus, a parasitic protozoon of the urogenital tract in cattle, presents a poorly known cytoskeleton, formed by rootlets and proteinaceous structures, many of which have not yet been characterized. Studies on its skeletal organization sheds light on the evolution of the matrix system, characteristic of higher eukaryotes. The skeletal matrix system of T. foetus in interphasic and dividing cells were studied using whole mount cell procedures observed either in field emission scanning electron microscopy (FESEM) or in transmission electron microscope (TEM) after the cell-sandwich technique, where the plasma membrane was mechanically removed. Three-dimensional-like images of the cell matrix were attained revealing a network of filaments that has not been described previously. Freeze-etching and cytochemistry using acridine orange for TEM, were also used. Membrane–skeleton interactions were examined in the hydrogenosomes, on the nuclear envelope at mitosis and interphase, and in the overall matrix filling of the cytoplasm and nucleoplasm. It was demonstrated that this eukaryote has a complex skeletal matrix other than just the rigid cytoskeletal structures. Our analysis indicated that the nucleus has a defined position, and fibrils perform an anchoring system for the nucleus. The possibility of a mechanism for nuclei fidelity migration during mitosis is discussed.
KeywordsCytoskeleton Nuclear matrix Protist Tritrichomonas foetus Cryotechniques Electron microscopy
This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Programa de Núcleos de Excelência (PRONEX), Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior (CAPES) and Associação Universitária Santa Úrsula (AUSU). The author also thanks the technical support given by William Christian Molêdo Lopes and Elivaldo de Lima.
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