Immunocytochemical localization of cytoskeletal proteins and electron microscopy of detergent extracted tachyzoites of Toxoplasma gondii.
Actin was located in tachyzoites of Toxoplasma gondii by indirect immunofluorescence using anti-actin antibodies. Fluorescence was seen in the region of the conoid of almost all cells. In about 75% of the cells, the whole anterior region showed fluorescence and in about 25% of the cells fluorescence was seen in the posterior region. No fluorescence was seen when permeabilized parasites were incubated in the presence of NBD-phallacidin which binds to F-actin. This observation, associated to the fact that no microfilaments were seen in transmission electron micrographs of Triton X-100 extracted, tannic acid-glutaraldehyde (TA-GA) fixed cells, indicate that in tachyzoites of T. gondii actin is predominantly in the monomeric form (G-actin). No fluorescence was observed when permeabilized parasites were incubated in the presence of antibodies specific to desmin, vimentin and keratin. Examination of Triton X-100 extracted, TA-GA fixed parasites showed that the outer membrane was partially removed while the inner membrane complex was not, but had a corrugated aspect. Connections between the sub-pellicular microtubules and the inner membrane complex and between the latter and the outer membrane were seen.
D000199:Actins / Q000032:analysis; D000546:Amanitins; D000818:Animals; D003598:Cytoskeletal Proteins / Q000032:analysis*; D003599:Cytoskeleton / Q000648:ultrastructure; D003902:Detergents; D005455:Fluorescent Antibody Technique; D008854:Microscopy, Electron; D014122:Toxoplasma / Q000254:growth & development / Q000648:ultrastructure*
D000199:Actins; D000546:Amanitins; D003598:Cytoskeletal Proteins; D003902:Detergents; C028877:7-nitrobenz-2-oxa-1,3-diazole-phallacidin