Cell wall ultrastructure and cation localization in some benthic marine algae

Abstract
Cell wall ultrastructure was compared in mature thalli of Cystoseira barbata (Goodenough et Woodward) J. Agardh (Phaeophyta), Gracilaria verrucosa (Hudson) Papenfuss (Rhodophyta) and Enteromorpha intestinalis (Linnaeus) Link (Chlorophyta), providing a structural basis for the study of cation localization (through the K antimonate precipitation technique). These species showed different amounts of antimonate precipitates and different patterns of cation localization in the apoplast. SEM X-ray microanalyses allowed the localization of sulphated polysaccharides through the S peak and identification of the cations present in the cell walls. The results suggest that in different species tha cation-binding properties of the cell wall polysaccharides may have varying importance in cellular ionic regulation.