On the ability of Anemonia sulcata (Coelenterata: Anthozoa) to absorb charged and neutral amino acids simultaneously

Abstract

Reciprocal inhibition experiments concerning the simultaneous absorption of acidic, basic and neutral amino acids give evidence that Anemonia sulcata Pennant (Coelenterata: Anthozoa) possess at least three distinct uptake systems for amino acids. The absorption of amino acids belonging to the same class is mutually inhibited. Increasing inhibitor concentrations reduce the uptake of the substrate successively, indicating that the receptors are saturated only at high substrate concentrations; this is not the case under natural conditions. The uptake system for acidic amino acids is highly specific; uptake is not inhibited by either basic or neutral amino acids. The specificity for basic amino acids is lower; uptake is influenced by neutral amino acids. Neutral amino acids are absorbed either by one single system with broad specificity or by several systems with overlapping specificity. D- and L-isomers seem to be absorbed by the same system, as the uptake is reciprocally inhibited. The restricted specificity of the amino-acid uptake systems, especially those for neutral amino acids, could be explained as an adaptation to avoid accumulation of certain amino acids in a most economic way. Moreover, a broad spectrum of various dissolved organic materials can thus be utilized. The experiments also give evidence that anemones are able to supply their metabolism completely with the necessary substances by absorbing dissolved organic material. The absorbed substances may, furthermore, be vital for the metabolism, although their individual energy content may be negligible. Anemones display optimum fitness to an important environmental factor-dissolved organic material — on a macromolecular level, in addition to structural and physiological adaptations.