Epixenosomes: Peculiar Epibionts of the Hypotrich Ciliate Euplotidium Itoi Defend Their Host Against Predators

摘要: . Euplotidium itoi harbors on its dorsal surface peculiar episymbionts (referred to as epixenosomes) equipped with a complex extrusive apparatus. In the laboratory. E. stocks without epixenosomes behave and reproduce like symbiotized stocks. hypothesis that play defensive role against predators was tested by comparing behavior of Litonotus lamella when preying upon Euplotes crassus, epixenosomes. discharges toxicysts direct-cell-to cell contact, paralyzes three types prey same efficiency. Nevertheless, can ingest Euplotes, epixenosomes, certain extent, whose ejecting capability has been inhibited. while it never eats unaltered each prey-type, about 60% individuals attacked toxicyst discharge are able recover their normal once transferred into pure sea water. This percentage for eaten predator corresponds probability survival. is lower other two prey-types in which engulfed do not have chance recover. These data support suggest involvement epixenosome's apparatus function.