Newly synthesized extracellular ribonucleic acids in the amphibian gastrula

The possible synthesis of RNA located in the extracellular compartment of Bufo arenarum gastrula was studied using a biochemical method. [3H]adenosine was microinjected into the blastocoel of late blastulae or early gastrulae, which were then dissociated at advanced gastrula stage. RNA was extracted from both, the cellular supernatant and the disaggregated cells, by the Kirby-phenol procedure. Most of the ethanol-precipitable radioactivity was sensitive to RNase and alkaline treatment. The partial characterization of these molecules indicate that the radioactive pattern of total RNA, found in sucrose gradients, the ratio Poly(A)+RNA/Poly(A)-RNA as well as the radioactive pattern of Poly(A) fraction in acrylamide gels were different in samples from cellular and from extracellular origin. Although not conclusive, these results are proposed as a new argument for the existence of an extracellular RNA in the amphibian embryo.