Authors

Discussion

Motile forms of apicomplexans are characterised by the presence of a surrounding three-layered pellicle consisting of an outer plasma membrane separated by a space (subplasmalemmal space, SPS) from two inner membranes which constitute the inner membrane complex (IMC).  There is strong evidence that the SPS contains the molecular apparatus enabling an actin-myosin interaction to propel the whole organism forwards during gliding or invasive motility.  Much is now known about the molecular composition of this apparatus ('glideosome'), but an understanding of the motile mechanism needs its visualisation by microscopic methods. A well-defined example of apicomplexan motility is seen in the invasion of red cells by Plasmodium merozoites.  In this presentation we report an electron microscopic study of the dynamic organization of the Plasmodium knowlesi merozoite pellicle during red cell invasion, allowing the creation of a model of directional motility based on interactions between orientated f-actin with fields of randomly orientated myosin assemblies.