Immunocytochemical localization of cytoskeletal proteins and electron microscopy of detergent extracted tachyzoites of Toxoplasma gondii

J Submicrosc Cytol. 1985 Oct;17(4):503-8.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / analysis
  • Amanitins
  • Animals
  • Cytoskeletal Proteins / analysis*
  • Cytoskeleton / ultrastructure
  • Detergents
  • Fluorescent Antibody Technique
  • Microscopy, Electron
  • Toxoplasma / growth & development
  • Toxoplasma / ultrastructure*


  • Actins
  • Amanitins
  • Cytoskeletal Proteins
  • Detergents
  • 7-nitrobenz-2-oxa-1,3-diazole-phallacidin