IMMUNOLOCALIZATION OF CENTRIN IN OXYRRHIS-MARINA (DINOPHYCEAE)

A new polyclonal antibody was raised against centrin isolated from the flagellate green alga Spermatozopsis similis (Chlorophyta; anti-SSC). It stains by Immunofluorescence and immunoelectron microscopy well-kn own reference systems for centrin like the nucleus-basal body connecto rs in Chlamydomonas reinhardtii (Chlorophyta) and the system fibers (r hizoplasts) of Scherffelia dubia (Chlorophyta). In addition, it recogn izes in immunoblots a single 20-kDa protein in isolated cytoskeletons of Spermatozopsis similis and Tetraselmis striata (Chlorophyta) as wel l as purified centrin isolated from Tetraselmis striata. Using this an tibody, centrin was localized in whole cells and isolated cytoskeleton s of Oxyrrhis marina Dujardin (Dinophyceae) by immunofluorescence and immunogold electron microscopy. In the flagellar apparatus of O. marin a, five different structures were antigenic. Four short fibers (connec tives 1-4) link the basal bodies to the four major fibrous flagellar r oots, which do not cross-react with anti-centrin. The most prominent o f the labeled structures (connective 5), a crescent-shaped fiber, exte nds from the flagellar canal of the transverse flagellum along the bas e of the tentacle to the flagellar canal of the longitudinal flagellum , interconnecting the distal parts of the microtubular roots/bands in the basad apparatus. For most of its length, it underlies and is conne cted to a transversely oriented subamphiesmal microtubular band. In im munoblot analyses, anti-SSC recognizes only a single 20-kDa protein in cytoskeletons of O. marina. Functional and phylogenetic aspects of ce ntrin-containing structures in dinoflagellates are discussed.