QUANTITATIVE AND QUALITATIVE ASPECTS OF PROTEIN SYNTHESIS IN PREIMPLANTATION RABBIT EMBRYO

Protein synthesis in the preimplantation rabbit embryo has been investigated quantitatively by liquid scintillation counting of radioisotope incorporated into TCA-insoluble material, and qualitatively by electrophoresis of soluble, labeled embryonic proteins. The rate of protein synthesis per embryonic cell decreases approximately 100-fold during the cleavage period, whereas it increases some 10-fold and remains constant shortly after cavitation and early blastocyst formation have occurred. The pattern of incorporation of radioisotope into soluble embryonic proteins changes to resemble the pattern of demonstrable bulk proteins as the embryo becomes a blastocyst. The question of the necessity of genetic transcription during cleavage is discussed. The data on protein synthesis are shown to be compatible with delayed genetic intervention in early mammalian development. © 1969.