EFFECT OF RETINOIC ACID AND VALPROATE ON SEA-URCHIN DEVELOPMENT

The effect of valproate and retinoic acid on Paracentrotus lividus dev elopment and fertilization is reported. Retinoic acid at concentration s between 5 mu M and 7 mu M causes severe disturbance of development a nd at 10 mu M complete embryo degeneration if added in the period from fertilization on. Concentrations up to 7 mu M are uneffective if reti noic acid addition is started 16 h after fertilization. Valproate at c oncentrations between 1 mM and 5 mM causes severe disturbances of deve lopment if added from 5 min after fertilization on. Concentrations of 20 mM are lethal to all embryos. If the drug is added 16 h after ferti lization no effect is observed up to the concentration of 10 mM. The e ffect of valproate is specific, because its isomere 2-en at 10 mM has very little effect on development. Both drugs affect fertilization onl y at higher concentrations: more than 1 mu M for retinoic acid and mor e than 10 mM for valproate.