The role of the cytoskeleton in brown algal physode movement

Phenolic compounds, packaged within vesicles known as physodes, are a major cytoplasmic constituent of eggs and zygotes of the Australasian fucoid Hor mosira banksii. Physode movement in early life stages of Hormosira is descr ibed. We have used the cytoskeletal inhibitors cytochalasin B, latrunculin B and nocodazole added during different stages of development to investigat e the role of the cytoskeleton in movement of these vesicles to regions of active wall formation in the growing rhizoid tip and the plane of cytokines is prior to cell division. Actin inhibition prevented polarization, cross-w all formation and physode movement. When microtubules were disrupted polari zation was still possible, but cross-wall formation and physode movement we re prevented. Both actin microfilaments and microtubules are necessary to m ove physodes to regions of accumulation and active wall formation.