Lack of coupling between DNA and histone synthesis in growth-arrested Friend erythroleukemia cells

Histone synthesis was studied in Friend cells growth-arrested by culturing in isoleucine-deficient medium for 20-24 hours. Such cells are characterized by a very low level of DNA synthesis (5% of the controls). In contrast, the labelling of total nuclear proteins and of total histones continues at an unreduced level for many hours. At the same time there is no accumulation of histones in the cell nucleus, suggesting histone turnover. The behaviour of histone H1 differs from that of the nucleosomal histones, a fact speaking in favour of the existence of independent control mechanisms.