Figure 1

Pre-invasive trajectories of GFP-expressing tachyzoites. (A) Pie graph showing the distribution of each type of pre-invasive motion, the absolute numbers are indicated, (B-C) DIC-GFP merged time lapses showing tachyzoite (B) impulse circular motion on top of HFF cells (top panel), and minimal impulse on top of Ptk-1 (medium panel) and NRK (bottom panel) cells, and (C) circular gliding onto NRK cells (top panel), helical gliding onto Ptk-1 cells (second panel) and twirling gliding onto M2 cells (bottom panel). The blue line reconstitutes the trajectory of the parasite apex; pink arrows define the junction; the last frame of each time lapse attests to tachyzoite entry; graphs show the tachyzoite speed over time and the pink arrows mark the starting point of the penetration event; all scale bars: 5 μm. DIC, differentia interference constrast; HFF, human foreskin fibroblasts; NRK, normal rat kidney fibroblasts; Ptk-1, rat kangaroo kidney epithelial cells.