Abstract
Protein synthesis in developing embryos of Bombyx mori was studied by means of microinjection experimens using tritium-labeled precursors and actinomycin D (AD). The incorporation of 3H-leucine into the acid-insoluble fraction was shown to be most active on the first day (stages 3-4) and during the fifth to ninth days (stages 6-20) after oviposition. In the diapausing egg the incorporation of 3H-leucine during stages 3 to 4 was not affected by AD, while the incorporation at the later stages was appreciably inhibited by AD. Two-dimensional gel electrophoresis followed by autoradiography using 35S-methionine demonstrated the existence of stage-specific peptides which were synthesized at different phases of development. The present results suggest that the translational event in the early stages of embryogenesis depends on pre-existing maternal mRNAs, and at the later stages of the embryonic development it depends upon newly synthesized mRNAs.
