IMSc Webinar

Malaria parasites as a novel model system for chiral active matter

Dr. Pintu Patra

Institute for Theoretical Physics, Heidelberg University

Collective motion of individuals is a remarkable example of self-organization exhibited by diverse systems, ranging from groups of animals to microorganisms to cytoskeletal filaments. Frequently, collective motion is found as a coherent circular or vortical motion of individuals and has been reported in diverse living systems such as fish schools, ant mills, bacterial swarms, as well as in synthetic active systems such as biofilaments driven by molecular motors and self-phoretic colloids. Such a vortical state of motion provides long-lived patterns that can be studied in detail to gain insight into the order and dynamics of individuals in active collectives. Here we show that Plasmodium sporozoites, a crescent-shaped form of malaria parasites, provide a novel and unique model system for active matter that combines the aspects of self-propulsion, curved shape, and mechanical flexibility into one system. First, we discuss their motion in collectives extracted from salivary glands of mosquitoes, a situation in which dozens of sporozoites form rotating vortices. Using quantitative image analysis, we find that single sporozoites within the vortices are sorted according to their curvatures and speeds. Further, we find that the vortices undergo oscillatory breathing in their shape. We explain these intriguing features of sporozoite vortices using agent-based simulations where each agent is represented by an active curved polymer that mimics a motile sporozoite. Next, we focus on the stick-slip motion of individual sporozoites that arises from the interplay between cell motility and surface adhesion. Using a stochastic multi-contact model for surface adhesion, we show the dependence of friction force and torque on their motility. We also connect the stochasticity in the adhesion dynamics to the deviations in the circularity of the motion. In summary, we establish malaria parasites as a new active matter system and provide novel insight into the individual and collective behavior of chiral active particles.

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Meeting ID: 921 7414 3986
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