An endocytic-secretory cycle participates in Toxoplasma gondii in motility
Fig 7
Uptake of SAG1 was also analysed by TEM. Secondary antibodies were coupled with 15-nm gold beads to label the parasites before incubation at 37 °C with Tf-LPA. (A-D) The three different labels observed by immunofluorescence assays (Fig 6) were also observed by TEM. (A) Parasite with αSAG1 bound to the membrane. (B) Parasite with αSAG1 capped. (C-D) Parasite with αSAG1 endocytosed at different locations. As for the NGP, the gold-coupled antibodies seem to be in translucent vesicles. (E) Transversal cut of a parasite, illustrating that labelling in different parts of the parasite can be observed at the same time even in TEM. Five close-up images are showing the different types of interactions. (1) Beads below the plasma membrane, (2) beads at the surface of the plasma membrane, (3) beads located on a budding vesicle, (4) bead located near the ER, (5) bead in very tight interaction with the membrane. ER, endoplasmic reticulum; NGP, nanogold particle; TEM, transmission electron microscopy; Tf-LPA, Top-Fluor lysophosphatidic acid.