VEGETALIZATION OF SEA URCHIN LARVAE INDUCED WITH cAMP PHOSPHODIESTERASE INHIBITORS

Treatment of sea urchin embryos with cAMP phosphodiesterase (PDE)-inhibitors such as caffeine (4×10⁻³ M), theophylline (8×10⁻³M), or nicotinamide (10⁻²M), at the morula stage for only a couple of hours, yields vegetalized larvae. Most of the embryos treated with these reagents before the morula stage develop to blastulae filled with mcsenchyme-like cells. Almost all embryos at the blastula stage develop normally even if they are treated with a PDE-inhibitor for a considerable period. The rate of ³H-valine incorporation into protein in the morulae is reduced by caffeine and theophylline, but does not decrease in the presence of nicotinamide. Actinomycin D cancels the vegetalizing effect of PDE-inhibitors on the morulae.