Regulation of Protein Synthesis in Embryos of Ilyanassa obsoleta

Much of the protein synthesis during early development in Ilyanassaresults from the translation of oogenetic mRNA. We show thatmicrotubule proteins are products of this translation, and thattheir synthesis is subject to translation level regulation.We also show that translation level regulation is involved inthe function of the polar lobe by making comparisons of theelectrophoretic patterns of synthesis of ¹⁴C labeled proteinsof normal embryos with the patterns of synthesis of ³H labeledproteins of embryos from which the polar lobes had been removedat the trefoil stage. Controls utilizing biochemical and morphologicalmarkers were performed to assure that normal and delobed embryoswere developing at equivalent rates. The expression of significantdifferences in the patterns of protein synthesis were foundbetween normal and delobed embryos, and these differences werenot dependent upon concomitant RNA synthesis. These differenceswere observable as early as after only 24 hours of development,although organogenesis does not begin until much later in development.Therefore, the observed differences probably reflect determinativeevents. The results support the hypothesis that the developmentaldeterminants of the polar lobe may include specific, preformedmRNA sequences, or specific regulators of translation.