title: The three-dimensional structure of the cytostome-cytopharynx complex of Trypanosoma cruzi epimastigotes.
abstract: The cytostome-cytopharynx complex is the main site of endocytosis of Trypanosoma cruzi epimastigotes. Little is known about the detailed morphology of this remarkable structure. We used serial electron tomography and focused-ion-beam scanning electron microscopy to reconstruct the entire complex, including the surrounding cytoskeleton and vesicles. Focusing on cells that had taken up gold-labeled tracers, we produced three-dimensional snapshots of the process of endocytosis. The cytostome cytoskeleton was composed of two microtubule sets--a triplet that started underneath the cytostome membrane, and a quartet that originated underneath the flagellar-pocket membrane and followed the preoral ridge before reaching the cytopharynx. The two sets accompanying the cytopharynx formed a 'gutter' and left a microtubule-free side, where vesicles were found to be associated. Cargo was unevenly distributed along the lumen of the cytopharynx, forming clusters. The cytopharynx was slightly longer during the G2 phase of the cell cycle, although it did not reach the postnuclear region owing to a bend in its path. Therefore, the cytopharynx is a dynamic structure, undergoing remodeling that is likely associated with endocytic activity and the preparation for cell division.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro 21941-902, Brazil.
authors.forename: Carolina L
authors.initials: CL
authors.lastname: Alcantara
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro 21941-902, Brazil.
authors.forename: Juliana C
authors.initials: JC
authors.lastname: Vidal
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro 21941-902, Brazil Diretoria de Metrologia Aplicada às Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia (Inmetro), Rio de Janeiro 20261-232, Brazil.
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro 21941-902, Brazil narcisa@biof.ufrj.br.
authors.forename: Narcisa L
authors.initials: NL
authors.lastname: Cunha-e-Silva
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D055032:Electron Microscope Tomography / Q000379:methods; D004705:Endocytosis; D008870:Microtubules / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000378:metabolism / Q000648:ultrastructure*
keywords: Cytostome; Electron tomography; Endocytosis; Trypanosoma cruzi