Blocking Synthesis of the Variant Surface Glycoprotein Coat in Trypanosoma brucei Leads to an Increase in Macrophage Phagocytosis Due to Reduced Clearance of Surface Coat Antibodies
Fig 8
Motility analyses show an increase in swim velocity in cells where VSG synthesis has been inhibited.
(A) T. brucei swims more persistently in the same direction after VSG synthesis is blocked. Particle motion tracks of cells where VSG221 RNAi was induced for 0 or 8 hours (h). Each track represents the distance travelled by an individual cell over the course of measurement. One image was captured every 200 ms (5 Hz) for 1.7 minutes. Scale bar: 200 μm. (B) There is a significant increase in swim velocity (or directional swimming) after the induction of a VSG synthesis block for 8 hours. Velocity is shown in μm per second (s). The whole population (2500 cells) is compared with 50 bi-flagellated cells from the induced or uninduced population. Statistical significance was determined with Student’s t-test (***P<0.0001). (C) Increase in angular persistence in cells where VSG synthesis has been blocked. The average (av.) angular persistence is shown in either the whole cell population or bi-flagellated cells. Angular persistence is denoted on an arbitrary continuous scale of -1 to 1 where a value of 1 indicates continuous swimming in the same direction as observed after a 2 second period, a value of 0 represents cells moving in a random direction after this time period, and a value of -1 represents a trypanosome observed swimming in the reverse direction after 2 seconds. 1500 cells from the whole population (pop.) and 50 bi-flagellated cells are analysed. The observed change in motility after the induction of a VSG synthesis block was highly significant (***P<0.0001). (D) Histogram distribution showing an increase in persistent directional swimming in cells where VSG synthesis was blocked. The data is from 1500 cells from the whole population (either untreated or where VSG221 RNAi has been induced for 8 hours) which are also analysed in panel (C).