Abstract
Effects of L-tryptophan and related compounds on larval settlement of barnacle Balanus amphitrite Darwin were examined. The settlement rate of young cyprids increased in proportion to L-tryptophan concentration (1.8×10-5M to 5.6×10-4M). The inducing effect of serotonin (5-hydroxytryptamine; 5-HT) on larvalsettlement was similar to that of L-tryptophan at the concentration range of 3.4×10-7M to 1.1×10-5M. When 5-HT was applied to old cyprids, however, no inducing effect of larval settlement was observed. On the other hand, reserpin, a depleting agent of neuroactive amines such as 5-HT in mammals, showed inhibitoryactivity on settlement of old cyprids at the concentration of 10-7M.
