[Nutritional and ecological aspects of the uptake of dissolved amino acids by Anemonia sulcata (Coelenterata, Anthozoa)].

Anemonia sulcata resorbs and accumulates tritiated L-amino acids dissolved in sea water in their natural concentrations (70-700 nmol/l).Resorption takes place mainly through the apical membrane of the ectoderm. Even after quite long periods of exposure autoradiography reveals that the amino acids resorbed are located in the ectoderm; this is attributable to its cytological structure. Electronmicrographs show that only the ectoderm bears microvilli.The rate uptake (2-10 μg/g wet weight/h) depends on the type of the amino acid and its concentration.The concentration below which only a very slight degree of uptake is detected ranges from 10-100 nmol/l for the different amino acids.Certain amino acids (phe, lys, leu, his, pro) are used mainly in metabolic synthesis. Others (gly, ser) are also used in oxidative processes, as indicated by the presence of tritium water which results from the oxidation of 3H-amino acids.The concentration of free amino acids in tentacle tissue has been analyzed. The concentration of glycine, for example, is greater by a factor of 107 in tissue than in the medium in which resorption takes place, showing that uptake is an active process.Calculation reveals that the actinians satisfy a substantial proportion of their metabolic requirements by resorbing organic material from the environment.