γ-tubulin localization during the cell cycle in Sphacelaria rigidula (Phaeophyceae, Sphacelariales) DEMOSTHENES KARYOPHYLLIS, BASIL GALATIS and CHRISTOS KATSAROS* University of Athens, Faculty of Biology, Department of Botany, Athens 15784, Hellas (Greece) Abstract γ-tubulin was localized by immunofluorescence for the first time in brown algae using a specific antibody raised against Dictyostelium discoideum γ-tubulin. Its distribution during the cell cycle was studied in vegetative cells of Sphacelaria rigidula. γ-tubulin was localized in the centrosome area during the whole cell cycle. During interphase, it appears as a weak fluorescent spot, while when the cell enters mitosis, the fluorescence increases, becoming broader and brighter at metaphase. The spot diameter and brightness decrease again by anaphase. The results show that γ-tubulin is a permanent centrosomal component in brown algal cells and its accumulation depends on the microtubule nucleation activity of the centrosomes. The functional role of γ-tubulin is discussed in comparison with other cell types.   < back .