The Cytoskeleton Architecture of Algivorous Protoplast Feeders (Viridiraptoridae, Rhizaria) Indicates Actin –Guided Perforation of Prey Cell Walls

We examined the distribution of F–actin and alpha–tubulin in the algivorous, viridiraptorid amoeboflagellates Orciraptor agilis and Viridiraptor invadens over their life histories using phalloidin conjugates and immunolocalization. During attack, both species form distinctive, F–actin–rich structures at the contact zone to the algal prey cell, which exactly match the species–specific cell wall perforations and resemble invadopodia and podosome rosettes of mammalian cells to a certain extent. Furthermore, F–actin is involved in the extraction of plastid material by Orciraptor and in prey cell invasion by Viridiraptor (here, F–actin localizes to a characteristic hyaline channel, which surrounds the streaming cytoplasm). The digestive–reproductive stages of viridiraptorids display a highly ordered microtubular cytoskeleton, whereas distinct phalloidin–positive actin structures could not be detected. We discuss the presumed function of F–actin during perforation and penetration of the algal cell wall by viridiraptorids, and compare the cytoskeleton architecture of these protoplast feeders to amoeboflagellates from different eukaryotic supergroups.

Source: Protist - October 31, 2016 Category: Molecular Biology Source Type: research