CELL-DIFFERENTIATION AND THE CYTOSKELETON IN ACETABULARIA

In multicellular organisms, differentiation of individual cells is typ ically linked to the development of the whole organism. As cells acqui re tissue-specific morphologies and become functionally specialized th ey lose in turn a number of other functions. A free living, single cel led organism, however, maintains all such functions. Compartmentalizat ion and intracellular communication are two basic principles by which expression of specialized features is achieved within a unicell. Both in turn depend on the structure and dynamics of the cytoskeleton. Gian t algal unicells lend themselves as experimental models for the study of the cytoskeleton, because the cytoskeletal arrays inside these cell s become equally enormous in size. Some of these organisms are large e nough to be mistaken for multicellular plants, equipped with holdfast, stem and assimilatory organ. The marine green alga Acetabularia is on e of these giant cells, which has already been well known to phycologi sts and cell biologists for several decades. The current review discus ses recent progress in the study of the cytoskeleton in Acetabularia a nd examines classic concepts of cell morphogenesis from the perspectiv e of cytoskeletal function.