||Collective migration describes the coordinated movement of larger groups of individuals and can be found in various different systems. Popular examples for collective migration can be found in schools of fish or skin cells during wound healing. In our project, we investigate the collective motion of the motile form of the malaria parasite, so-called sporozoites, which are injected into the skin of the host by a mosquito. This stage of a devastating disease, killing around one million people every year, is still not fully understood and thus difficult to treat. Studying the movement of sporozoites will help us to gain a fundamental understanding of their internal organization, way of propagation, and dependencies on the environmental conditions. Especially the high packing density of the sporozoites within the salivary of the mosquito indicates a highly organized sorting process. Thus, it is highly suggestive that interactions of sporozoites are not random, but based on highly directed interactions and unique motility features.
We focus especially on an interesting and novel form of sporozoite migration occurring in freshly prepared salivary glands. Here, the sporozoites move in a highly collective fashion resulting in whirl like structures. The goal is to determine the critical parameters necessary for the appearance of whirl formation and their objective as well as automated characterization. This will improve our understanding of the collective behavior of sporozoites necessary during the complex packing mechanisms inside the salivary glands, but also lead to a functional model system, which can be used to predict possible weak spots to target in drug development.
Here, we present an automated, custom designed and user-friendly image processing strategy for quantitative analysis of time-resolved in vitro image sequences. Image sequences are subsequently analyzed regarding parameters such as number, speed, characteristic trajectories and curvature of the sporozoites in respect to their position within the whirl. As whirls can be observed to exhibit broad morphological variations, we present ideas to substantiate collectivity during the migration process as well as address difficulties associated with whirl characterization.