Effect of cornin on nucleic acid synthesis during early development in sea urchin eggs

The present investigation was carried out to see effects of muscle cornin, an alcoholic fiaction of boiling-water extract from rabbit skeletal muscle, on the nucleic acid synthesis in the early development of Pseudocentrotus depressus. In this study, the author used the assay method of our own device by which we can estimate the incorporation into whole cell simultaneously that into nucleic acid fraction, with one and the same specimen. The results of the observations are briefly summarized as follows. 1) Cornin accelerated the incorporation of 3H-uridine into whole cell by 10-20 %. 3H-thymine, 3H-thymidine and 3H-uracil all inhibited such incorporation. 2) As to the incorporation into the RNA, it was retarded in the course of phosphorylation at the synthetic stage. 3) In the incorporation into DNA, since the incorporation is inhibited by about 2/3 at the synthetic stage, it seems that the polymerization is inhibited. 4) This inhibition of the DNA synthesis was also substantiated by the autoradiography with tritiated thymidine. Some coments were made on the operation of the nucleic acid synthesis, the specific protein structure during the early development of sea urchin egg, and effects of cornin on these as well as on the other intrinsic substances.