Cytochemical Investigations of Deoxyribonucleic Acid-mediated Control of Ribonucleoprotein Metabolism
THE interdependence of various types of macromolecular synthesis in the cell has been demonstrated by the use of various antimetabolites. Synthesis of some ribonucleoproteins (RNP) in the nucleus is dependent on continued formation of deoxyribonucleic acid (DNA)1-3. One of these ribonucleoproteins is present in the nucleolus in the form of spherules called `nucleolini'3. When synthesis of DNA was inhibited by 5-fluorodeoxyuridine (FUDR), the nucleolini were at first enlarged and later disappeared. The pars amorpha of the nucleolus was not reduced during this process3. Further cytochemical observations and biochemical investigations of HeLa cells, grown as previously described3, and treated with 2 × 10-5 M FUDR are presented here.