PRESENCE AND DISTRIBUTION OF IMMUNOREACTIVE FMRFAMIDE AND BOVINE PANCREATIC POLYPEPTIDE-LIKE PEPTIDES IN A PROTOCHORDATE ASCIDIAN

FMRFamide and bovine pancreatic polypeptide (BPP) immunoreactivities w ere detected in the cerebral ganglion and in the alimentary tract of t he protochordate ascidian Styela plicata. Neurons expressing immunosta in to FMRFamide were mainly found in the cortical zone of the ganglion and a network of immunoreactive beaded nerve fibers was present in th e neuropil. Co-localization of FMRFamide- and BPP-like materials was d emonstrated in few nerve cell bodies and both peptides likely play a n eurotransmitter role. Parallely, endocrine-like cells containing FMRFa mide-like materials were distributed among the esophageal and gastric epithelia, whereas no PP immunostaining was found. The tetrapeptide co uld be involved in the regulation of the digestive processes by means of endocrine and/or paracrine mechanisms.