ABSTRACT
We describe studies using a monoclonal antibody, K1, that recognizes specifically the polypeptides with apparent molecular weights of 56 and 58 kilodaltons in the egg of the starfish, Asterina pectinifera. Antibody Kl reacted with extracts prepared from ovaries, oocytes, morulae, blastulae, gastrulae or bipnnariae, but brachiolariae, testes, pyrolic ceca, body walls and tube-feet did not contain any antigenic molecules. Extracts of eggs of the starfish, Asterias amurensis or of several sea urchin species did not react with antibody Kl. Among the members of the genus Asterina, extracts of brachiolariae of A. batheri and A. minor were not reactive whereas blastulae and brachiolariae of A. pseudoexigua pacifica contained an antigenic component. In contrast to the antigen peptides in A. pectinifera eggs, the apparent molecular weight of the antigen molecule in embryos and larvae of A. pseudoexigua pacifica was 41 kilodaltons, which represents a remarkable phylogenetic alteration of antigen molecules.
