Biochemical aspects of cardiac muscle differentiation. Deoxyribonucleic acid synthesis and nuclear and cytoplasmic deoxyribonucleic acid polymerase activity.

摘要: DNA synthesis and polymerase activity have been measured in terminally differentiating cardiac muscle of the rat. Incorporation [3H]thymidine into essentially ceases by 17th day postnatal development. Cardiac neonatal rats contains at least two molecular species polymerase: a 3.5 S that can be extracted from nuclei with 0.2 m potassium phosphate 6 to 8 soluble cytoplasmic polymerase. The nuclear crude extracts has pH optimum 9.0 is more active native than denatured as primer-template. 7.5 DNA. decreases 80-fold 1 17 after birth, which correlates temporally reduced rate synthesis. remains relatively constant throughout Mixing experiments (assay enzyme adult extracts) gave additive results, suggesting decline apparently not due presence absence activators or inhibitors different times during These studies may provide system used investigate control cellular proliferation terminal stages differentiation.