Die Bedeutung einiger anorganischer Komponenten des Seewassers für die Turgorregulation vonChaetomorpha linum (Cladophorales)

Abstract

The importance of some inorganic components of sea water for the turgorregulation of Cbaetomorph¢ linura (Chladophorales). Some algae of the intertidal zone are capable of regulating their turgor pressure. In 1896 DxEvs had already shown that this process is affected primarily by accumulation (positive turgor-regulation) or extrusion (negative turgot-regulation) of mineral salts and that transformation of stock material (e. g. starch) into osmotic active substances (e. g. sucrose) and vice versa plays no important role. His results are being confirmed by the present paper. In Chaetomorpha linurn (MOLLER) KOTZINC, lowering of salinity resulted in a significant release of potassium and chlorine (negative turgor-regulation). Changes in sodium content were only small. In algae exposed to a salinity of 30°o, the total sodium concentration was only about 10% that of the external medium. Salinity increase ted to a marked accumulation (positive turgor-regulation) of potassium and chlorine. Even in this process sodium was engaged only to a small degree -despite its high concentration in the surrounding medium. In both cases internal changes in sodium content amounted only to about 5 % of the total osmotic changes in the external medium. Aiter transfer from 30 %0 salinity into isosmotic artificial sea water without Ca", a rapid loss of potassium and chlorine was observed. The abrupt decrease of the calcium content accompanied by a marked swelling of cell walls, leading to a significant reduction of cell space, is interpreted as ion exchange process changing the cell wail Ca" against Na.EINLEITUNG

The pressure-dependence of the hydraulic conductivity, the membrane resistance and membrane potential during turgor pressure regulation inValonia utricularis

“…This means that A~c~=Arc ~ is valid over the whole investigated osmolarity range. This result which is expected for an exact turgor pressure regulation as defined by Kesseler [18] indicates therefore that only the number of the ions in the external medium (i.e., the colligative properties) play a role during turgot pressure regulation. This is important to note for the measurement of the pressure dependence of the membrane p.d.…”

“…The hydraulic conductivity was calculated from the measured k-values, from the stationary and applied pressures, and from the cell surface area and the cell volume according to Eqs. (17) and (18) in the Appendix.…”

“…Three mechanisms of regulation are found in nature: regulation via water transport [10], via synthesis of osmotically active substances [4,16,21] and via ion transport [18,24,29]. The last mechanism has been observed in cells of Chaetomorpha linum, a littoral alga, which can adapt to large variations of the external osmotic pressure.…”

Ionic relations and the regulation of turgor pressure in the marine alga,Valonia macrophysa

“…Evidence for turgor regulation in some other marine algae was obtained by Kesseler (1964Kesseler ( , 1965 and Bisson and Gutknecht (1975). Recently a pressure sensitive C1-pump was found in the giant celled marine alga, Halicystis parvula (Graves, 1974).…”

The interaction of salinity and temperature on the growth ofCaulerpa prolifera (Foerskäl) lamouroux

“…Also, it was observed that large algal coenocytes and many other plants accumulate chloride and discriminate against sulphate (EPPLEY, 1958). Dilution of sea water brings about the escape of chloride ions from Chaetomorpha linum (KESSELER, 1964).…”