Synthesis of RNA in Isolated Cells from Xenopus laevis Embryos

Abstract

INVESTIGATIONS with amphibian embryos are of particular interest because of the recent finding that a sequential synthesis of RNA species takes place during early development: the first, synthesized during very early stages, is soluble RNA, followed by ribosomal RNA, the synthesis of which predominates later^1,2. These sequential events may provide a parameter of cellular differentiation. The embryo has, however, a definite disadvantage: it needs few exogenous substances except for several inorganic ions which it requires until the feeding stage. For nucleic acid and protein synthesis carbon dioxide is perhaps the only available precursor which can be incorporated freely into the embryo³. We have found that the cells obtained from dissociated embryo actively incorporate a number of radioactive precursors when these are added to the medium and synthesize RNA species sequentially as do whole embryos.