Cytoskeletal Components of an Invasion Machine—The Apical Complex of Toxoplasma gondii
Figure 1
Image and Drawing of T. gondii
(A) Combined DIC and epifluorescence image of human fibroblasts infected with transgenic T. gondii expressing GFP-tubulin (green). Parasitophorous vacuoles containing 1, 2, 4, or 8 parasites are seen.
(B) Drawings of T. gondii (modified from [3] and [68]). Left: a longitudinal section of a dividing cell. Lobes of the dividing nucleus bordered by ER, Golgi (yellow), and developing rhoptry (mauve) are surrounded by the developing daughters' scaffolds (red). Maternal and daughter conoids are shown in green, secretory organelles (rhoptries) in purple. T. gondii has three membranes: a plasma membrane (black) and two additional layers (IMC, red) formed from a patchwork of flattened vesicles. Right: semitransparent view showing subpellicular MT (green).
(C) Enlarged view of the apical complex cytoskeleton, showing the conoid (green), preconoidal, and polar rings (brown), and two intraconoid MT (green). The conoid is formed of 14 fibers of tubulin (not MT), 430 nm long, arranged in a left-handed spiral [10]. Cytoskeletal elements, including the subpellicular MT (green) and a 2-dimensional lattice of intermediate filament-like proteins (not shown), are closely associated with the cytoplasmic face of the IMC.