THE PROTEIN-SYNTHETIC LESION IN UNFERTILIZED EGGS

Abstract

Analysis of amino acid incorporation by various cell-free systems from sea urchin eggs and embryos shows that all soluble fractions are functional in eggs as well as embryos. The low incorporation of eggs and systems derived from them is not due to deficiencies in cofactors nor to the presence of a protein synthesis inhibitor. The lesion seems rather to be an incapacity of otherwise normal ribosomes to translate the maternal messages. These messages are held in a masked condition on heavy particles or particle complexes. As a consequence of fertilization some messenger RNA is released, and free ribosomes, which are present in a large excess, combine with it for translation.