Transcriptional activity in lysates of cultured mesenchymal cells from embryonic tooth germs

Mesenchymal cells isolated from the papilla of embryonic tooth germs of the mouse were cultured in a complex medium for five to six days. Liquid nitrogen lysates, prepared from these cells, incorporated nucleoside monophosphates into a cold acid-insoluble product. The product was sensitive to RNase and no product was formed if the lysate was pretreated with DNase. The reaction was sensitive to EDTA and, in its presence, optimum activity was obtained with 2 mM MgCl2. On sucrose gradients, the reaction product was distributed between two broad peaks; one centered about 18S and the other above 28S. The RNA polymerase inhibitor alpha-amanitin inhibited approximately 50% of the activity at a concentration of 10 microgram/ml.