Immunological comparisons of major cortical cytoskeletal proteins in four entodiniomorphid ciliates

Summary Biochemical and immunological studies of the membrane cytoskeleton were carried out using the entodiniomorphid ciliated protozoa: Entodinium bursa, Eudiplodinium maggii, Epidinium caudatum and Polyplastron multivesiculatum. Immunological cross-reactions within the four ciliates show significant labelling of proteins with the same or different molecular weights among species. Antigenic homologies among cytoskeletal proteins with variable MW suggest that Ophryoscolecidae have maintained both a similar architectural organization and a cytoskeletal function while diversifying the MW of many cytoskeletal proteins. A comparative study of the antigenic relationships points away from an evolutionary lineage from simplest (the ancestral Entodinium) to more complex (the intermediate Eudiplodinium and the more advanced Epidinium and then Polyplastron), and also the linear evolution based on the increasing complexity of the cytoalimentary system. It suggests a bushy evolution by radiation from unknown ancestral forms. This is supported by sequencing of the different entodiniomorphid ribosomal RNAs.