Hydroxyurea and Escherichia coli nucleoside diphosphate reductase.

M). The cultures were incubated at 37° for 40 mm (“Pretreatment―), whereupon the bacteria were washed and resuspended in fresh Medium HA. Portions from each culture were distributed into flasks containing premeasured amounts of the various drugs (“Additions―). After receiving cytidine-3H (2 @ig/ml; 0.13 i@Ci/ml),the cultures were incubated with aeration at 37°for 20 mm and quadr.uplicate 0.5-mi portions were withdrawn from each culture; 2 of these were processed immediately for radioactivity determination (“Total nucleic acids―), while the other 2 were subjected to alkali digestion (18) prior to radioactivity measurement (DNA).