DNA metabolism during infection of Anacystis nidulans by cyanophage AS-1. VI. Effect of hydroxyurea and nalidixic acid on the development of cyanophage AS-1.

The use of the DNA inhibitors hydroxyurea (HU) and nalidixic acid (NAL) to elucidate patterns of DNA metabolism in AS-1 infected A. nidulans have led to several conclusions. First, HU and NAL at concentrations of 500 and 100 micrograms/ml, respectively, inhibited DNA synthesis in synchronized A. nidulans. Protein and chlorophyll synthesis remained essentially unchanged as did turbidity increases. Second, the complete burst size of the cyanophage AS-1 was severely affected by HU and NAL treatment and burst sizes of 8 and 2.6, respectively, were obtained. Third, inhibitor treatment of infected cultures caused a premature release of phage at 12 h instead of 16 h post infection. Finally, HU treatment of the host cell had no effect on the formation of PIL-DNA, whereas NAL pretreatment blocked its formation.