Protein degradation during preimplantation development of the mouse

The half-lives of labelled proteins were determined for mouse preimplantation embryo stages from the germinal vesicle oocyte to the early blastocyst. While no significant differences were found among half-lives for 1-cell stages, or among half-lives for cleavage stages, a significant (P less than 0.05) 28% decrease in half-life was observed between the 1-cell and the cleavage stages. Labelled protein half-lives were 18.2 and 13.1 h for the 1-cell and cleavage stages respectively. Fertilization probably initiates this increase in protein degradation rate although no significant decrease was detected until after the first cleavage.