Stimulating Effect of Nucleoprotein Fraction of Chick Embryo Extract on Homologous Heart Fibroblasts.

Summary 1. A quantity isolation method is described for a chick embryo nucleoprotein fraction based on von Euler and Heller's(10) procedure for liver nucleoproteins. 2. When this fraction was tested in an assay medium of un-dialyzd chicken plasma and dilute un-dialyzed horse serum large outgrowths of chick heart fibroblasts were obtained with well-defined alterations in cell morphology and mode of outgrowth. 3. The nucleoprotein fraction described contains protein, 10.3% PNA, 0.3% DNA and has a characteristic nucleoprotein absorption spectrum. 4. High polymer pentose nucleic acid isolated according to Nishioka and Ibuka(9) produced no changes in size or appearance of assay cultures.