Nuclear basic protein acetylation during early sea urchin development

Abstract

The acetylation of nuclear basic proteins was studied during early Strongylocentrotus purpuratus development (32–64 cell stage to pluteus formation). 1. 1. There are basic nuclear proteins present at the 32–64 cell stage that coelectrophorese with all of the histone fractions of a more advanced stage. The most highly acetylated proteins at this early cleavage stage are those that migrate in position of the F3 and F2a1 arginine-rich histones. 2. 2. At the early blastula, mesenchyme blastula, gastrula, prism and pluteus stages, the lysine-rich histone F1 is minimally acetylated. The extent of acetylation of the F2b-F2a2 slightly lysine-rich histones varies somewhat during development and is highest at the mesenchyme blastula and gastrula stages. F2a1 acetylation is slightly lower at prism stage. 3. 3. 10 −3 M puromycin inhibits prism stage protein synthesis completely, but total protein acetylation continues at grater than two-thirds the normal rate. 4. 4. Late gastrula stage embryos were pulse-labeled for 1 h with [ 14C]acetate and [ 3H]thymidine. During a 1-h cold chase period, the [ 14C]acetyl groups of fractions F2a1 and F2b-F2a2 decayed twice as fast as the labeled DNA, indicating rapid turnover of the histone acetyl groups. The above results suggest that the acetylation of invertebrate histone fractions is very similar to mammalian histone acetylation.