Conference Agenda

Almost all cells have a shape, size, and organisation specialised for their functions. During replication, malaria parasites are amorphous and disorganised. By contrast, their host-cell-invading ‘zoite’ stages exhibit extreme apical-basal polarity, with invasion-specialised organelles at their apical end. It is currently unclear when this transition begins, how it is initiated, or what proteins control it.

Using ultrastructure-expansion microscopy, we imaged blood-stage, liver-stage, and mosquito-stage malaria parasites from replication until the completion of zoite formation to identify how this disorganised to hyper-polarised transition occurs. In all three lifecycle stages, the first sign of polarity establishment in the parasite was the anchoring of a structure called the centriolar plaque to the parasite plasma membrane. Subsequently, the parasite would begin to build its invasion-specialised organelles at this site, suggesting that this anchoring event represents the establishment of apical-basal polarity. In blood-stage parasites we observed a dramatic repositioning of the Golgi following centriolar plaque anchoring, providing a potential mechanism for how this event triggers apical organelle biogenesis. Work is currently ongoing to define the centriolar plaque proteins that coordinate the establishment of polarity within the parasite. Collectively, this study provides new insights into the biology of daughter cell formation in malaria parasites.