Biomaterial Database

Localization of lectin-binding sites and sugar-binding proteins in tachyzoites of Toxoplasma gondii. 1991

L de Carvalho, and T Souto-Padrón, and W de Souza

Departamento de Parasitologia e Biofísica Celular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil.

Lectins and neoglycoproteins labeled with colloidal gold particles were used for the ultrastructural localization of carbohydrate residues and sugar-binding sites, respectively, in thin sections of tachyzoites of Toxoplasma gondii embedded in the Lowicryl K4M resin. Incubation of the sections in the presence of gold-labeled Canavalia ensiformis (Con A), Arachis hypogaea (PNA), Ricinus communis I (RCA I), Triticum vulgaris (WGA), and Limax flavus (LFA) agglutinins showed significant labeling of the rhoptries. However, no labeling of the parasite's surface was observed. Incubation of tachyzoites in the presence of gold-labeled albumin-N-acetyl-D-glucosamine or albumin-galactose, but not in the presence of albumin-mannose, led to labeling of the rhoptries in a pattern similar to that observed with the lectins. The results obtained are discussed in relation to the possible role played by secretion of rhoptry macromolecules during the process of T. gondii-host cell interaction.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D002241	Carbohydrates	A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of Cn(H2O)n. The largest class of organic compounds, including STARCH; GLYCOGEN; CELLULOSE; POLYSACCHARIDES; and simple MONOSACCHARIDES.	Carbohydrate
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D006651	Histocytochemistry	Study of intracellular distribution of chemicals, reaction sites, enzymes, etc., by means of staining reactions, radioactive isotope uptake, selective metal distribution in electron microscopy, or other methods.	Cytochemistry
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D014122	Toxoplasma	A genus of protozoa parasitic to birds and mammals. T. gondii is one of the most common infectious pathogenic animal parasites of man.	Toxoplasma gondii,Toxoplasma gondius,Toxoplasmas,gondius, Toxoplasma
D037102	Lectins	Proteins that share the common characteristic of binding to carbohydrates. Some ANTIBODIES and carbohydrate-metabolizing proteins (ENZYMES) also bind to carbohydrates, however they are not considered lectins. PLANT LECTINS are carbohydrate-binding proteins that have been primarily identified by their hemagglutinating activity (HEMAGGLUTININS). However, a variety of lectins occur in animal species where they serve diverse array of functions through specific carbohydrate recognition.	Animal Lectin,Animal Lectins,Isolectins,Lectin,Isolectin,Lectin, Animal,Lectins, Animal