Abstract
The mitotic delay was induced when sea urchin eggs were treated with either ethidium bromide or puromycin, as observed with eggs fertilized with X or UV-irradiated sperm. Treatment of these eggs with caffeine during the period of early prophase block resulted in the reduction of the mitotic delay. Protein synthesis of these eggs was not affected by X-irradiation but inhibited by ethidium bromide or puromycin. Caffeine was almost ineffective in changing the protein synthesis of eggs inseminated with X-irradiated sperm or treated with ethidium bromide. These facts mean that additive synthesis of protein is not required for the reduction by caffeine of the mitotic delay. Some role of protein synthesis in the reduction by caffeine of the cleavage delay is not excluded for puromycin treated eggs, since caffeine counteracted the inhibitory effect of puromycin on protein synthesis.
