The Form and Function of the Cytostome‐Cytopharynx of the Culture Forms of the Elasmobranch Haemoflagellate Trypanosoma raiae Laveran & Mesnil

Abstract

SYNOPSIS. In the culture forms of the elasmobranch trypanosome Trypanosoma raiae is found a prominent cytopharyngeal complex. This consists of a group of 5 or 6 microtubules associated with a deep invagination of the cell membrane which arises from a cytostome near the opening of the flagellar pocket. This structure is a constant feature of the various epimastigote and trypomastigote forms that this flagellate has in culture. Replication of the cytopharyngeal apparatus is completed before cytokinesis. Experiments using ferritin as an electron dense tracer show that endocytosis occurs from the blind ending of the cytopharynx both in the exponential and stationary phases of growth in vitro. Ferritin is transported from the cytopharynx by endocytotic vesicles to large, membrane‐bound vacuoles in the posterior region of the cell. Ultrastructural location of non‐specific acid phosphatase within these digestive vacuoles and also within the Golgi apparatus is reported. Coated vesicles found in association with the flagellar pocket are another route of uptake of ferritin by T. raiae.

Trypanosomes infecting cod Gadus morhua L. in the North Atlantic: a resurrection of Trypanosoma pleuronectidium Robertson, 1906 and delimitation of T. murmanense Nikitin, 1927 (emend.), with a review of other trypanosomes from North Atlantic and Mediterranean teleosts

“…A few species have been cultured (e.g. T. boissoni, T. carassii, T. cobitis, T. granulosum and T. rajae) and the ultrastructure of cultured forms have consequently been studied using the transmission electron microscope (Boisson, Ranque, Mattei, & Manfredi 1967;Davies, Thorborn, Mastri, & Daszak 1999;Lom 1979;Lewis & Ball, 1981;Preston 1969;). An identification of the vector involved, trypanosome vector-phase development and experimental demonstration of the vertebrate host range is an ultimate objective for all trypanosome species, but may be difficult to accomplish in marine environments.…”

Character evolution in heterotrophic euglenids

“…MTR-like structures have been found in a variety of phototrophic euglenids, which implies that they are derived from bacteriotrophic ancestors Wibel 1985a, 1985b;Surek and Melkonian 1986;Owens et al 1988). Current evidence suggests that the MTR is not homologous to the more complex feeding apparatus of rods and vanes as both kinds of apparatus can occur within the same cell (e.g., Dinema) (Farmer and Triemer 1988a;Triemer and Ott 1990;Triemer and Farmer 1991a); in these cases, the MTR is assumed to be vestigial or to function in pinocytosis as it does in trypanosomatids (Preston 1969;Brooker 1971;Lom et al 1980). Thus, there appear to be two unrelated types of feeding apparatuses: the MTR and the rod-and-vane-based apparatus.…”

“…glenids and (2) if so, why? Both kinds of feeding apparatus are present in some euglenids (e.g., Dinema), where the MTR is assumed either to be vestigial or to function in pinocytosis rather than phagotrophy (Preston 1969;Lom et al 1980). The presence of both kinds of apparatus in the same cell implies that the rod-and-vane based apparatus evolved independently from the MTR.…”

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

“…The participation of microtubules in the structuring of the cytostome-cytopharynx complex is a hallmark of trypanosomatids (Steinert and Novikoff, 1960;Preston, 1969) and bodonids (Attias et al, 1996). However, the origin of these microtubules and their exact positioning and arrangement around the cytopharynx remained unclear.…”

“…The existence of a microtubule quartet that is common to both the flagellar pocket and the cytostome-cytopharynx complex led us to question whether these microtubules correspond to a conserved quartet of microtubules that surrounds the flagellar pocket in other trypanosomes (Preston, 1969;Taylor and Godfrey, 1969;Lacomble et al, 2009;Girard-Dias et al, 2012). In T. brucei, this conserved quartet is often referred to as the MtQ (microtubule quartet), and it comprises the only microtubules associated with the flagellar-pocket membrane.…”