UV-irradiation of sea urchin eggs changes the course of the Ca-activated ATPase activity

UV-irradiation of sea urchin eggs extends the time of increased Ca²⁺-ATPase activity of the first peak in the cell cycle if the eggs are irradiated before fertilization and the time where in controls the activity of the first peak declines. Irradiation after this time causes delay of the second cell cycle; it extends also the duration of increased enzyme activity of the first peak in the second cycle. The enzyme itself does not seem to be UV-sensitive as UV-irradiation of homogenates does not alter the enzymatic activity.