Boothroyd Lab In the Department of Microbiology & Immunology

Toxoplasma Images and Movies

Egress and invasion movie

Download movie [20.5 MB .avi]

This movie shows at 4x real speed, a vauole of Toxoplasma inside a monolayer of human foreskin fibroblasts. Upon addition of a calcium ionophore, the parasites become highly motile and exit the infected cell. You will see them invade nearby cells, especially if you focus on the parasites at "5 o'clock" in the vacuole. Movie shot by Gustavo Arrizabalaga.



Tachyzoite electron micrograph

Tachyzoite electron micrograph

This shows a Toxoplasma tachyzoite that is extracellular and in the primed for invasion, as evidenced by the protruded anterior tip that includes the microtubular "conoid". Micrograph shot by John Boothroyd while on sabbatical in David Ferguson's lab.



The moving junction

moving junction

The four panels are different images of the same parasite that is halfway into a host cell it is invading. During invasion, there is a circular ring of contact between the parasite and host cell plasma membrane. This migrates down the parasite during invasion, and is thus called the moving junction. RON4 precisely colocalizes with the moving junction throughout invasion. E. Phase image. F. Immunofluorescent staining of the surface antigen SAG1 (done prior to permeabilization so only the portion of the parasite that is still outside the host cell is accessible). G. Immunofluorescent staining of the moving junction component RON1 (so-called because it starts life in the RhOptry Necks). H. Merged image of F and G.

Images shot by Dave Alexander and from his paper in PLoS Pathogens in 2005.

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