Messenger RNA in Early Sea-Urchin Embryos: Cytoplasmic Particles

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Science  08 Oct 1965:
Vol. 150, Issue 3693, pp. 214-217
DOI: 10.1126/science.150.3693.214


Three structures containing messenger RNA can be demonstrated in the cytoplasm of early sea-urchin embryos: (i) particles that sediment more slowly than ribosomes and contain newly synthesized DNA-like RNA, (ii) light polyribosomes, which also contain this newly synthesized RNA, and (iii) heavy polyribosomes, which seemingly contain only already existing or "maternal" messenger RNA and account for the bulk of the synthesis of protein.