In vitro RNA synthesis and nuclear proteins of isolated sea urchin embryo nuclei

Abstract

Isolated nuclei and/or chromatin from Strongylocentrotus purpuratus gametes and early developmental stages were analyzed for their basic protein content as well as their ability to serve as templates for in vitro RNA synthesis. 1. 1. Sperm chromatin exhibited little or no template activity. Unfertilized egg nuclei directed 1.5 % of the RNA synthesized by pure sperm DNA. This level of template activity increased at 32–64 cell, blastula and gastrula stages reaching a maximum of 6 % during pluteus stage. 2. 2. Trypsin digestion of sperm chromatin and blastula nuclei caused a 6–8-fold increase in template activity. Similarly treated egg nuclei showed no increase in available template. Sonication of egg and blastula nuclei resulted only in a slight increase in template activity. This was less pronounced for egg nuclei. Sonicated and trypsinized blastula nuclei showed an increased template activity over controls. Similar treatment of egg nuclei resulted in no release of genetic restriction. 3. 3. Typical histone patterns could not be electrophoretically demonstrated from extracted nuclear protein prior to blastula stage. 4. 4. The above results indicate a lack of histones during early sea urchin development although there is substantial template restriction.