Effect of actinomycin D on protein synthesis by delayed implanting mouse embryos in vitro.

Abstract

AbstractBlastocysts were collected from the uteri of intact or ovariectomized mice and incubated with or without actinomycin D in a medium containing [14C] amino acids. In the absence of actinomycin D the rate of amino acid incorporation by blastocysts from intact mice (i.e., normal embryos) was constant; the rate of amino acid incorporation by blastocysts from ovariectomized mice (i.e., delayed implanting embryos) was initially low and increased to the normal value after four hours in vitro. In the presence of actinomycin D the rate of amino acid incorporation by normal embryos was only slightly reduced but the expected increase in the rate of amino acid incorporation by delayed implanting embryos was completely blocked. It is suggested that metabolic “activation” of delayed implanting mouse embryos requires the synthesis of new RNA.