POLYSACCHARIDE LOCALIZATION IN THE CELL-WALL OF PORPHYRA-LEUCOSTICTA (BANGIOPHYCEAE, RHODOPHYTA) DURING THE LIFE-CYCLE

In the two alternating phases of the life cycle of Porphyra leucostict a different fibrillar polysaccharides are present in the cell wall: ce llulose in the conchocelis and xylans in the gametophyte. The enzyme-c olloidal gold technique has been used for the identification and the l ocalization of both these polysaccharides and a comparison has been ma de with the PATAg test. The higher specificity of affinity cytochemist ry allowed us to confirm the presence of cellulose only in the conchoc elis, and to localize it in the inner layer of the cell wall. Likewise , the xylans were identified in the gametophytic phase and also locali zed in the inner zone of the cell wall. The possibility that mannans c ould be located in both phases in the outer part of the wall at the th allus surface is proposed.