Species-Specific Adaptations of Trypanosome Morphology and Motility to the Mammalian Host
Fig 6
Extended single flagellar beat analysis of trypanosome motility in wet mouse blood.
The graphs plot the velocities produced by single, consecutive flagellar beats (red dots), together with the beat frequency (black dots). The velocities, which were derived from measurement of the translocation of the posterior tip after each flagellar beat (white marks in S8–S16 Videos), are averaged over 5 beats to generate the average directional speeds (blue dots). The red number is the overall observation period (ms). A) Fast type of a T. vivax IL 1392 persistent swimmer with a slim waveform (S8 Video), showing a 30 ms—stop upon mechanical hindrance. The flagellar tip directly hit an erythrocyte, whereupon the trypanosome stopped without flagellar beating being interrupted. Translocation resumed with the next flagellar beat. Note that neither beat frequency nor average velocity (blue line) were markedly changed by this stop. B) Example of a T. vivax IL 1392 normal waveform swimmer revealing a short (< 1 second) period characterised by several base-to-tip beats, resulting in backward movement, i.e. negative speed (S9 Video). C) T. vivax IL 2136 exhibited lower beat frequencies than the IL 1392 strain (S10 Video). D) An intermediate T. brucei ILTat 1.4 swimmer exhibited two persistent swimming stretches interrupted by a short tumbling phase. This was followed by a period of beat reversal and backward swimming (S11 Video). E) A persistently swimming T. evansi parasite (S12 Video) reducing velocity by half, while the flagellar beat frequency remained in a constant range. (F) T. congolense IL 1180 showed a short period of rather fast backward motion (S13 Video). (G) T. congolense KETRI 3827 switching between fast forward and slow backward movement (S14 Video). H) T. congolense KETRI 3827 isolated from infected sheep revealing persistent slow forward motion (S15 Video).