Translational regulation of histone synthesis in the sea urchin strongylocentrotus purpuratus

Abstract

The pattern and schedule of histone synthesis in unfertilized eggs and early embryos of the sea urchin Strongylocentrotus purpuratus were studied using two-dimensional gel electrophoresis. After fertilization there is an abrupt change in the pattern of histone variant synthesis. Although both cleavage-stage- and β-histone mRNA are stored in sea urchin eggs, unfertilized eggs synthesize only cleavage-stage (CS) variants. However, after fertilization, both CS and α messages are translated. Since histone mRNA isolated from unfertilized eggs can be translated in vitro, the synthesis of α histone subtypes appears to be under translational control. Although the synthesis of α subtypes is shown here to occur before the second S phase after fertilization, little or no α histone is incorporated into chromatin at this time. Thus, early chromatin is composed predominantly of CS variants probably recruited for the most part from the large pool of CS histones stored in the unfertilized egg. © 1982, Rockefeller University Press., All rights reserved.