title: [Cortex-wall connections in the apical cell of Sphacelaria].
abstract: The apical cell of Sphacelaria (Fucophyceae) exhibits a permanent polarized organization throughout asymmetric divisions. The apex organization was studied by immunolocalization of tubulin, vitronectin, alpha-actinin and beta 1 integrin. Microfilaments were stained directly by fluorescein phalloidin. The apex was highly organized around a patch of microfilaments densely packed at the tip, where vitronectin-like and alpha-actinin-like proteins colocalized. In the same area, an actin-dependent targeted secretion of sulfated polysaccharides was shown. The permanent localization of these components throughout cell elongation suggests that a cortical site involving transmembrane connections between the cytoskeleton and the extracellular matrix is required for cell polarity. A model of the organization of the tip is proposed.
authors.affiliation: Laboratoire de morphogenèse végétale expérimentale, université de Paris-Sud XI, Orsay, France. georges.ducreux@mve.u-psud.fr
authors.forename: A
authors.initials: A
authors.lastname: Ouichou
authors.forename: G
authors.initials: G
authors.lastname: Ducreux
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000648:ultrastructure; D000185:Actinin / Q000032:analysis; D016764:Cell Polarity; D002473:Cell Wall / Q000737:chemistry / Q000648:ultrastructure*; D005109:Extracellular Matrix / Q000737:chemistry / Q000648:ultrastructure; D019012:Integrin beta1 / Q000032:analysis; D000459:Phaeophyceae / Q000737:chemistry / Q000648:ultrastructure*; D014404:Tubulin / Q000032:analysis; D019096:Vitronectin / Q000032:analysis
chemical_list: D019012:Integrin beta1; D014404:Tubulin; D019096:Vitronectin; D000185:Actinin