Abstract
In callus and tumor tissues of Nicotiana tabacum cultured for 39 days in media supplemented with various concentrations of hydroxyurea (1.3 x 10-4 M - 1.3 x 10-3 M) a decrease of DNA content (ca. 24 per cent in callus tissue and ca. 23 per cent in tumour tissue) and a decrease of RNA content (over 10 per cent and ca. 9 per cent in callus and tumour tissue, respectively) was observed. The autoradiographic method showed that a long-lasting action of this com-pound inhibits RNA synthesis. A stronger inhibitory influence of hydroxyurea upon incorporation of 3H-uridine from the incubation medium was revealed.