Fig. 4

Calcium responses within the rhinophore ganglion. a The schematic drawing of the rhinophore illustrates the location of two measurements during two experiments (shown in b, d). The shaded area (in a, c) indicates the measured region (RG: rhinophore ganglion). The position of five regions of interest (ROIs) is shown and signals of these ROIs are plotted in b. Scale bar = 100 μm. b: Stimulation with the amino acids (all 20 mM) alanine (ALA), arginine (ARG), isoleucine (ILE), methionine (MET), glutamine (GLU) and with artifical sea water containing high potassium (ASW^K+). Clear responses to ALA and ARG were found in the regions I–IV, whereas ILE, MET, and GLN induced no calcium response. Region V showed a weak response to ARG. All regions responded to ASW^K+. c: The location of three ROIs of a second experiment is shown in c. d: Signal changes to repeated application of ALA. Within region I the calcium level decreased, where as the calcium levels of regions II and III increased. e: A simultaneous elevation and decrease in ratio signals measured in different ROIs was found in three additional experiments to the application of ALA, ILE, and GLN