Intercellular Migration among Phylogenetically Distant Host Cells by an Ameboid Embryo of a Parasitic Wasp
Abstract: For endoparasitic organisms, entering the host body is essential. During the immature stage of its life cycle, the insect parasitoid Copidosoma floridanum feeds onanother insect. The morula-stage embryos of C. floridanum can move like amoebae and actively invade host embryos by using molecular mimicry. Our previous study showed that cadherins and C-type lectins are involved in this phenomenon. This is the first report showing a receptor–ligand interaction between heterologous multicellular organisms. Electron microscopy analyses of cellular interactions between the extraembryonic syncytium of invading parasitic morula and the host embryonic epithelial cells clearly showed that morula penetration into the host embryo causes no damage to the host cells. Epithelial cells of the host embryo extended microvilli toward invading C. floridanum morula and adjacent host cells in the same way. Shortly after settlement of the morula within the host body cavity, small gap junctions and adherens junctions with host cells were formed. The morula was then surrounded by a cyst comprised of host cells into which host tracheoles were invaginated.
Key words: Parasitic wasps, invasion, self-recognition, cadherin, lectin