Poly(A)-containing RNA in early embryogenesis of sea urchins

The content, biosynthesis and template activity of poly(A)+ RNA in the early stages of sea urchin development have been studied. The amount of poly(A)+ RNA reaches a maximum at the middle blastula stage in polyribosomes and at the 8-blastomere stage in the cytoplasm. Poly(A)+ RNA synthesis becomes noticeable at the 64-blastomere stage and the spectrum of newly synthesized molecules is different from that at the middle blastula stage. The products of translation in vitro of poly(A)+ RNA at all the stages studied show insignificant differences and contain a major group of polypeptides of molecular mass 10-20 kDa.