NONCONSERVATIVE DNA REPLICATION IN BACTERIA AFTER THYMINE STARVAT1ON* BY CRELLIN PAULINGt AND PHILIP HANAWALT

15 Cavalieri, L. F., and R. G. Nemchin, Biochim. Biophys. Acta, 87, 641 (1964). 16 Rauen, H. M., H. Kersten, and W. Kersten, Z. Physiol. Chem., 321, 139 (1960). 17 Reich, E., personal communication. 18 Kirk, J. M., Biochim. Biophys. Acta, 42, 167 (1960). is Dingman, C. W., and M. B. Sporn, Science, 149, 1251 (1965). 20 Langridge, R., and P. J. Gomatos, Science, 141, 694 (1963). 21 Hamilton, L. D., W. Fuller, and E. Reich, Nature, 198, 538 (1963). 22 Erickson, R. L., and W. Szybalski, Virology, 22, 111 (1964). 23 For this experiment the virus was prepared as described in Experimental, but subjected to an additional cycle of equilibrium centrifugation in CsCl; it was then incubated with micrococcal nuclease (20 ug/ml; Tris buffer 0.05 M, pH 8.6; 0.01 M Ca++) for 7 hr at room temperature, followed by overnight dialysis against Tris buffer 0.01 M pH 7.9, brought to 0.15 M NaCl-0.01 M phosphate buffer pH 7.4, and incubated with crystalline pancreatic DNase (200 ug/ml; 0.01 M Mg++; 1 /2 hr at room temperature and 19 hr at 40C). After this treatment the virus was again dialyzed against PBS, harvested by centrifugation, and the RNA extracted with phenol. The Tm of this RNA was identical with that obtained in the usual way, and it contained components of 10.6, 12.5, and 14.9S. With RNA polymerase in a standard assay 3.5 1Ag of this RNA directed the incorporation of 0.005 msumole of radioactive CMP into acid-precipitable material; under the same conditions 4 1Ag b-cell DNA promoted synthesis of 0.74 miumole CMP into polynucleotide.