Protein Synthesis During the First Three Cleavages in Pond Snail Eggs (Lymnaea Stagnalis)

Abstract

Egg cells of the pond snail Lymnaea stagnalis were isolated and reared in an inorganic medium, in which they reached the blastula stage with the same rate and yield as in the egg capsules. Synchrony of cell division was 70—90% depending on temperature and number of cell division. 3H-leucine incorporation into hot TCA-insoluble material as a function of developmental stage was studied by autoradiography. The rate of leucine incorporation during the metaphase of the first three cell divisions was found to be ca. 30% of the incorporation rate during the corresponding interphases. The interphase rates increased from a very low level before nuclear fusion to a 25 fold value in the third interphase. 3H-leucine incorporation could be inhibited by 78% by 5 × 10-3 M puromycin and hence seems to represent protein synthesis.