[Effects of 2-mercapto-1(β-4-pyridethyl) benzimidazole on the development and metabolism of the egg ofParacentrotus lividus].

A reversible inhibitor of ribonucleic acid synthesis, 2-mercapto-1-(β-4-pyridethyl) benzimidazole (MPB), provoked vegetalization of sea urchin larvae. Some structural analogues of MPB showed no vegetalizing effect. Two other inhibitors of ribonucleic acid synthesis, Cordycepin and 5,6-dichloro-(β-D-ribofuranosyl) benzimidazole, did not exert vegetalizing effects. MPB inhibited oxygen consumption. This inhibitor diminished the rate of incorporation of uridine and valine into acid-insoluble material. The mode of action of MPB is discussed. It is suggested that this agent exerts a control at post-transcriptional levels.