A study of ribonuclease and desoxyribonuclease during the early developmental stages of Rana pipiens

Abstract

1. 1. A spectrophotometric method for the determination of RNase and DNase activities in frog embryo homogenates has been described. 2. 2. Cyclical variations in RNase and DNase activities have been found during the early development of the frog. 3. 3. RNase activity decreases on fertilization but progressively increases throughout cleavage and reaches a maximum during early blastulation. From mid-blastulation through the beginning of gastrulation, there is a rapid decrease in RNase activity. At mid-gastrulation the activity abruptly increases to a maximum value and then declines until just prior to neural plate formation. At this time the activity again increases rapidly but soon declines when the neural plate becomes evident. 4. 4. DNase activity declines only slightly on fertilization. It declines slowly during cleavage and early blastulation but during mid-blastulation, there is an abrupt increase in activity which reaches a maximum at the beginning of gastrulation. It then declines sharply to a minimum value during the early gastrulation stages. At mid-gastrulation, there is another rapid increase in DNase activity which reaches a maximum and then declines until just prior to neural plate formation at which time a slight increase in activity is seen.