CYTOSKELETAL DYNAMICS OF APEDINELLA-RADIANS (PEDINELLOPHYCEAE) .3. POST-DIVISION DEVELOPMENT, MAINTENANCE OF CELL SYMMETRY, AND THE REESTABLISHMENT OF INTERPHASE MORPHOLOGY

The dynamics of the cytoskeletal proteins centrin, actin, and tubulin were investigated during post-division development in the radially sym metrical phytoflagellate Apedinella radians (Pedinellophyceae). Each d aughter cell inherits a triangular arrangement of centrin filamentous bundles that develops, during post-division, into the six-pointed star configuration observed at interphase. This coincides with development al processes including plaque duplication and migration, chloroplast d ivision and migration, and spine-scale deployment. Centrin filamentous bundles appear to be involved in maintaining radial symmetry througho ut the cell cycle and re-establishing interphase morphology. Actin fil amentous bundles, prominent at interphase, depolymerize just prior to mitosis and do not reform until late post-division, indicating they ar e not involved in maintaining cell symmetry during cell division. Alth ough the precise dynamics of microtubular triads and their associated cylindrical caps has not been determined, they may work in concert wit h centrin filamentous bundles in re-establishing interphase morphology . Three centrin, or centrin-like, components in A. radians appear to c oordinate independent architectural events during the cell cycle. The nature of the three centrin components is discussed and compared to th e flagellar roots/pericentriolar material of the eukaryotic centrosome .