On the selective adsorption of cations in the cell wall of the green algaValonia utricularis

Abstract

The selective adsorption of the cations Na +, K +, Mg ++ and Ca + + by the cell wall of the Mediterranean alga Valonia utricularis (Siphonocladales, Chlorophyceae) from sea water of 40 Too S was investigated by extraction of cell-wall preparations, eluted before in 1.1 mol methanol {adjusted to pH 8) with 0A n formic acid in a Soxhlet apparatus. Na + and K + were determined by flame photometry, Mg ++ and Ca + + by complexometric titration with EDTA. From calculation of the dry weight:fresh weight ratios and the chloride determinations in the eluates, the Donnan freespace fraction of the total cell-wall volume was calculated to about 35 %, and the analytical results of the cation concentrations in the extracts expressed as ~Val cm -3 DFS. This calculation is based on the assumption that the acidic groups of the noncellulosic matrix material, carrying negative charges by dissociation at the reaction of sea water (ph about 8) are responsible for the adsorption of cations by exhibition of a Donnan effect. The results obtained show clearly that besides the divalent cations Mg ++ and Ca + +, which according to the physico-chemical laws of the Donnan distribution must be relatively accumulated to the second power of the monovalent ones, potassium is also enriched by selective adsorption, and the K + :Na + ratio increased significantly compared with that in sea water. This seems to indicate that the strength of attraction between the cations and the negative sites is dependent on the radii of the ions and the state of hydration and/or polarisation of the ions and binding sites.

Helgoland and the history of research on marine benthic algae

“…Lebenszyklen von Planktonalgen werden mit Schwerpunkt hinsichtlich der Diatomeen und parasitischer Protophyten durch Gerhard D r e b e s untersucht, beziighch der Dinoflagellaten durch Malte E 1 b r ~i c h t e r (Drebes, 1974;Drebes & Elbr&chter, 1976). Die Dynamik im Helgol~inder Phytoplankton verfolgt Erik H a g rn e i e r, w~hrend die ione~physiologischen Untersuchungen an Meeresalgen von Hanswerner K e s s e 1 e r (bis zu seiner Pensionierung im Jahr 1987) eine bereits von Kommann in Neapel begonnene Thematik aufgreifen (Kornmann, 1934;Kesseler, 1980).…”

Biology of the Integument

“…14) or in simple microvillar-type cuticles (e.g. Finally it should be pointed out that the selective adsorption of ions on the cell wall of roots in higher plants and in marine algae is the primary step in the uptake and accumulation of salts (Kesseler 1980). 1 a-c).…”