MICROSCOPIC OBSERVATIONS ON TISSUE CALCIUM DISTRIBUTION IN THE BROWN ALGA, UNDARIA-PINNATIFIDA (HARVEY) SURINGAR

The distribution of Ca2+ in thallus tissues of the brown alga Undaria pinnatifida was investigated by microspectro-photometric analysis after fixation with Carnoy's reagent and staining with an alizarine sulfonate dye. Ca2+ accumulation in the young thallus was much higher in mucilage cells of the basal than the apical region; there was least in the pith of the basal region. A roughly uniform pattern was found in the stipe from the central part of the young thallus, while a highly irregular pattern occurred in both stipe and blade from the corresponding area of the mature thallus; the Ca2+ content was much lower than in the cortex, mucilage cells and vacuoles of the mature stipe than in the corresponding area of the young stipe. The contents of all regions of the mature blade were higher than those in the young blade; they were particularly high in mucilage cells.