Flagellar Motility ofTrypanosoma cruziEpimastigotes

Abstract

The hemoflagellate Trypanosoma cruzi is the causative agent of American trypanosomiasis. Despite the importance of motility in the parasite life cycle, little is known about T. cruzi motility, and there is no quantitative description of its flagellar beating. Using video microscopy and quantitative vectorial analysis of epimastigote trajectories, we find a forward parasite motility defined by tip-to-base symmetrical flagellar beats. This motion is occasionally interrupted by base-to-tip highly asymmetric beats, which represent the ciliary beat of trypanosomatid flagella. The switch between flagellar and ciliary beating facilitates the parasite's reorientation, which produces a large variability of movement and trajectories that results in different distance ranges traveled by the cells. An analysis of the distance, speed, and rotational angle indicates that epimastigote movement is not completely random, and the phenomenon is highly dependent on the parasite behavior and is characterized by directed and tumbling parasite motion as well as their combination, resulting in the alternation of rectilinear and intricate motility paths.

Experimental and Mathematical-Modeling Characterization of Trypanosoma cruzi Epimastigote Motility

“…It has been reported [ 12 ], and we have observed it as well, that T. cruzi epimastigotes move along their longitudinal axis, pulled by their flagellum. From this fact, we assumed that, at a given step, the parasite velocity is parallel to its longitudinal axis, and that the orientation of this axis changes from one step to the next.…”

“…However, despite its importance, parasite motility has been mostly disregarded. A previous report by our group [ 12 ] suggests that T. cruzi movements involve a propulsion term, as well as non-propelling fluctuations similar to Brownian motion. Similar studies on a related parasite, T. brucei , studied with more detail its motility.…”

High-speed multifocal plane fluorescence microscopy for three-dimensional visualisation of beating flagella

“…The motility of Trypanosoma cruzi and Leishmania have been less extensively analysed, however flagellum motility is likely similarly multifunctional 14 . Swimming of Leishmania promastigotes and T. cruzi epimastigotes have also been analysed and cell movement and swimming behaviours are somewhat unlike T. brucei 2,15,16 . As for T. brucei, they are not always free in a large fluid volume and, when densely packed, will also likely undergo hydrodynamic coupling of movement which could give collective movement of a population at the macro scale.…”

“…In Leishmania promastigotes and T. cruzi epimastigotes this is near-planar 2,16,17 . These organisms can also switch to a base to tip beat 5,[15][16][17][18] . In T. cruzi epimastigotes and Leishmania promastigotes this reversed beat is asymmetrical (a ciliary type beat) and causes a rotation of cell orientation 15,16,18 .…”

“…These organisms can also switch to a base to tip beat 5,[15][16][17][18] . In T. cruzi epimastigotes and Leishmania promastigotes this reversed beat is asymmetrical (a ciliary type beat) and causes a rotation of cell orientation 15,16,18 . In T. brucei the reversed beat is not so well characterised (outside of mutants with a reversed beat 19 ) but occurs at a lower frequency and with a higher amplitude 5 and can cause slow backwards swimming and 'tumbling' 5 -rapid cell reorientation associated with a contorted cell shape 20 .…”