CELL-WALL ULTRASTRUCTURE AND CATION LOCALIZATION IN SOME BENTHIC MARINE-ALGAE

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 Speak and identification of the cations present in the cell walls. The results suggest that in different species the cation-binding properties of the cell wall polysaccharides may have varying importance in cellular ionic regulation