THE ACCUMULATION OF VANADIUM AND MANIFESTATION OF AN ANTIGEN RECOGNIZED BY A MONOCLONAL-ANTIBODY SPECIFIC TO VANADOCYTES DURING EMBRYOGENESIS IN THE VANADIUM-RICH ASCIDIAN, ASCIDIA-SYDNEIENSIS-SAMEA

The present experiments, using a combination of thermal-neutron activation analysis for the determination of vanadium and an immunofluorescence method for the recognition of the manifestation of an antigen specific to vanadocytes, clearly revealed the time at which ascidians gain their unusual ability to accumulate vanadium ions during their development. Significant accumulation of these ions was observed after metamorphosis. Two and half months after fertilization, the amount of vanadium in juveniles was about 930 ng per individual, a concentration corresponding to more than 5 orders of magnitude greater than that in unfertilized eggs. A vanadocyte-specific antigen, recognized by a monoclonal antibody specific to the signet ring cells, first appeared in the body wall after metamorphosis. Three weeks after metamorphosis, the antigen became evident within the cytoplasm of the coelomic cells, which have a single, small vacuole. One and a half months after metamorphosis, signet ring cells appeared for the first time and were specifically recognized by the monoclonal antibody. It is suggested that the accumulation of the vanadium coincides with the differentiation of the vanadocytes during the development of ascidians.