The Cytostome of Trypanosoma cruzi and T. conorhini*

Milder, Regina Vugman; Deane, Maria P.

doi:10.1111/j.1550-7408.1969.tb02335.x

Cited by 56 publications

(28 citation statements)

References 16 publications

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“…In fact, some of these vesicles were connected with the cytopharynx membrane and contained the endocytic tracer Tf-Au. Although the presence of vesicles near the side of the cytopharynx is documented in the literature (Milder and Deane, 1969;de Souza et al, 1978), the occurrence of endocytosis in this region had never been demonstrated. Therefore, by using a labeled endocytic tracer, we have demonstrated that there is active membrane traffic at the naked side of the cytopharynx.…”

Section: Discussionmentioning

confidence: 99%

“…Since the initial description of the cytostome-cytopharynx complex of T. cruzi epimastigotes (Milder and Deane, 1969), very little further knowledge about this structure was gained, despite its great importance as the main site of endocytosis at this stage of the life cycle. This was due to the difficulty in following this structure in its entirety when using only analyses of two-dimensional (2D) micrographs.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the diameter of the cytopharynx varies along its length. Until now, the cytopharynx was described as having a funnel-shaped openingthe cytostome -followed by a tube-like element with a roughly homogeneous diameter along its length -the cytopharynx properwhich terminates in a bag-shaped structure (Milder and Deane, 1969;de Souza et al, 1978). Based on this description, it was assumed that endocytosis occurred exclusively at the enlarged end of the cytopharynx.…”

Section: Journal Of Cell Sciencementioning

confidence: 99%

“…This domain is characterized by a prominent glycocalyx and is known as the 'preoral ridge' (Martínez-Palomo et al, 1976;Pimenta et al, 1989;VataruNakamura et al, 2005). Also, an uncharacterized set of microtubules and vesicles are aligned with the cytopharynx (Milder and Deane, 1969), but the microtubule arrangement and the origin and function of the aligned vesicles are still unknown.…”

Section: Introductionmentioning

confidence: 99%

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The three-dimensional structure of the cytostome-cytopharinx complex of Trypanosoma cruzi epimastigotes

Alcantara

Vidal

Souza³

et al. 2014

Journal of Cell Science

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Journal Of Cell Sciencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The three-dimensional structure of the cytostome-cytopharinx complex of Trypanosoma cruzi epimastigotes

Alcantara

Vidal

Souza³

et al. 2014

Journal of Cell Science

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“…Trypanosoma cruzi, the causative agent of Chagas disease in Latin America, appears as an attractive model for studies to elucidate the occurrence of lipid rafts and their probable participation in endocytic processes, as T. cruzi epimastigotes have a second specialized endocytic site, the cytostome/ cytopharynx. This is a plasma membrane invagination located at the anterior cell end, which penetrates deeply into the cytoplasm towards the nucleus (Milder & Deane 1969). Uncoated vesicles have been observed budding off from the flagellar pocket membrane (Soares et al 1992) …”

Section: Uptake Of Transferrin By Epimastigote Forms Of the Protozoanmentioning

confidence: 99%

Transferrin uptake may occur through detergent-resistant membrane domains at the cytopharynx of Trypanosoma cruzi epimastigote forms

Corrêa

Atella

Vargas

et al. 2007

Mem. Inst. Oswaldo Cruz

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Uptake of transferrin by epimastigote forms of the protozoan Trypanosoma cruzi occurs mainly through a cytostome/ cytopharynx, via uncoated endocytic vesicles that bud off from the bottom of the cytopharynx. We have here examined whether detergent-resistant membrane (DRM) domains might be involved in this process. Purified whole cell membrane fractions were assayed for cholesterol levels and used in dot blot analyses. Detergent-resistant membrane markers (cholera B toxin and anti-flotillin-1 antibody) presented positive reaction by dot blots in cholesterolrich/ protein-poor membrane sub-fractions. The positive dot blot fraction was submitted to lipid composition analysis, showing composition similar to that of raft fractions described for other eukaryotic cells.Immunofluorescence assays allowed the localization of punctual positive signal for flotillin-1, matching the precise cytostome/ cytopharynx location. These data were confirmed by immunofluorescence assays with the co-localization of flotillin-1 and the transferrin uptake site. Our data suggest that DRM domains occur and are integrated at the cytostome/ cytopharynx of T. cruzi epimastigotes, being the main route for transferrin uptake.Key words: cytopharynx -detergent-resistant membrane -endocytosis -Trypanosoma cruzi -ultrastructure The lipid raft model proposes that cholesterol and sphingolipids of the plasma membrane outer leaflet are not randomly distributed, but rather clustered into micro-domains that float in the lipid bilayer, characterizing detergent-resistant membrane (DRM) domains in eukaryotic cells (Rietveld & Simons 1998, Handcock 2006. Transmembrane proteins (receptors, adhesion molecules, and enzymes) in the lipid bilayer would either reside in, and thus become sorted into transport vesicles, or be excluded from the rafts, depending on partitioning imparted by their physical properties (Harder et al. 1998, Simons & Vaz 2004.Lipid rafts play a role in a wide range of important biological processes, including signal transduction pathways, apoptosis, cell adhesion and migration, organization of the cytoskeleton and protein sorting during both exocytosis and endocytosis (Simons & Toomre 2000, Harris & Siu 2002.Flotillins are cholesterol-binding proteins that associate with a subset of rafts named caveolae, and are frequently used as raft markers. The flotillin protein family consists of the small (45 kDa) proteins flotillin-1 and flotillin-2/ ESA (a close homologue of the epidermal surface antigen). These proteins induce caveolae formation, bind cholesterol, and interact with signaling molecules (Anderson 1998, Kiss et al. 2004. Lipid rafts can exist independently of caveolae, but they must exist prior to formation of caveolae for proper insertion of flotillin into membranes (Graf et al. 1999, Ikonen 2001.Trypanosomatid protozoa have a particular cell body array that allows uptake of nutrients only at a specific membrane site: the flagellar pocket (Morgan et al. 2001). Trypanosoma cruzi, the causative agent of Chagas disease in Latin America, a...

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The Ultrastructure of Pathogenic Flagellates

Vickerman

1974

Novartis Foundation Symposia

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The Cytostome of Trypanosoma cruzi and T. conorhini*

Abstract: SYNOPSIS. A cytostome is described in culture forms and in intracellular stages of Trypanosoma cruzi and in culture forms of T. conorhini. The organelle opens into the flagellar pocket or close to it and runs deeply into the cell.

Cited by 56 publications

References 16 publications

The three-dimensional structure of the cytostome-cytopharinx complex of Trypanosoma cruzi epimastigotes

The three-dimensional structure of the cytostome-cytopharinx complex of Trypanosoma cruzi epimastigotes

Transferrin uptake may occur through detergent-resistant membrane domains at the cytopharynx of Trypanosoma cruzi epimastigote forms

The Ultrastructure of Pathogenic Flagellates

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