title: Giardia duodenalis: a freeze-fracture, fracture-flip and cytochemistry study.
abstract: The freeze-fracture technique was used to study the structural organization of the membranes of trophozoites of the protozoon Giardia duodenalis. No special array of intramembranous particles was observed in the membrane lining the protozoon body or the flagella. A large globular protuberance located in the ventral region displayed several small circular indentations similar to those seen in the dorsal region. These also occurred on the parasite surface as revealed in fracture-flip replicas. A large number of vesicles were observed below the plasma membrane; they corresponded to an acidic compartment as indicated by fluorescence microscopy of acridine orange-stained cells and contained acid phosphatase as indicated by cytochemistry. In addition, gold-labeled macromolecules (albumin, peroxidase, transferrin, and low-density lipoprotein) accumulated in the vesicles. These observations suggest that the peripheral vesicles of trophozoites are part of the endosomal-lysosomal system of G. duodenalis.
authors.affiliation: Departamento de Parasitologia e Biofísica Celular, Instituto de Biofísica Carlos Chagas Filho, Brazil.
authors.forename: W M
authors.initials: WM
authors.lastname: Kattenbach
authors.forename: P F
authors.initials: PF
authors.lastname: Pimenta
authors.forename: W
authors.initials: W
authors.lastname: de Souza
authors.forename: P
authors.initials: P
authors.lastname: Pinto da Silva
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D005614:Freeze Fracturing; D005872:Giardia / Q000201:enzymology / Q000648:ultrastructure*; D006651:Histocytochemistry; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence
chemical_list: D000135:Acid Phosphatase