Cell Surface Carbohydrates in Tritrichomonas foetus1

Abstract

The cell surface of Tritrichomonas foetus was characterized by using 18 highly purified lectins with specificities for N-acetyl glucosamine, N-acetyl galactosamine, galactose, mannose, and sialic acid. The specificity of the lectin-induced cell agglutination was verified by inhibition of the agglutination with the specific sugars. By using cytochemical techniques associated with electron microscopy, carbohydrates were detected on the cell surface of T. foetus. The following techniques were used: periodic acid--thiosemicarbazide--silver proteinate, concanavalin A--horseradish peroxidase, and ruthenium red. Anionic sites were detected on the cell surface of the protozoan at pH's 1.8 and 7.2 with the use of colloidal iron hydroxide and cationized ferritin particles, respectively. The binding of colloidal iron particles, as well as the agglutination induced by the lectin from Limulus polyphemus, indicated the presence of sialic acid on the cell surface of T. foetus.

Transient invagination of flagella by Tritrichomonas foetus

“…The size of internalized particles or structures does not necessarily determine which mechanism predominates, although in mammalian macrophages the contribution of phagocytosis generally increases with increasing particle size (Pratten and Lloyd 1986;Koval et al 1998). A very active endocytic machinery exists at the T. foetus cell surface (Benchimol et al 1981(Benchimol et al , 1986(Benchimol et al , 1990(Benchimol et al , 1992Queiroz et al 1991;Aonso et al 1994Aonso et al , 1997Granger and Warwood 1996;Tachezy et al 1996Tachezy et al , 1998, raising the possibility that the¯agella might be laterally internalized by a process akin to receptor-mediated endocytosis. Hypertonic medium inhibits clathrin-mediated endocytosis in mammalian cells by preventing clathrin from interacting with adaptor proteins (Daukas and Zigmond 1985;Hansen et al 1993); these conditions also inhibited¯a-gellar internalization by T. foetus.…”

“…T. foetus exhibits concanavalin A-binding sites uniformly over its surface, including its¯agella (Benchimol et al 1981). Concanavalin A at 250 mg/ml has been shown to inhibit the endocytosis of certain receptors (Pippig et al 1995), but it had no eect on T. foetus¯agellar internalization (although it did inhibit subsequent externalization).…”

Fine structure of Tritrichomonas foetus as seen using cryotechniques

“…Associations of ER and hydrogenosomes were observed as well as transient modifications of membrane organelles. Anterior flagella presented the characteristic rosettes, suggesting that conventional freezefracture studies (Benchimol et al, 1981) showed no artifactual structures.…”

Cell-surface carbohydrates of Entamoeba invadens

“…In general these surface carbohydrate residues resemble many other protozoan cell types, including Tritrichomonas, Herpetomonas, Leishmania, Trypanosoma, and Crithidia, in having saccharide ligands on their plasma membrane as revealed by lectin-agglutination tests (Sixel et al 1978;Pereira et al 1980;Benchimol et al 1981;Esteves et al 1982;Schottelius and Uhlenbruck 1983;Schottelius 1987). In addition, fucose residues were not detected in E. invadens using Ulex europaeus (UEL) and Lotus tetragonolobus (LTL) lectins.…”