STUDIES ON GENE ACTIVITY IN SYNCHRONIZED CULTURES OF MAMMALIAN CELLS

Cultures of KB cells synchronized by excess thymidine treatment were used to study the synthesis of DNA-like RNA (D-RNA) and the enzymes lactic dehydrogenase and fumarase during the mammalian cell cycle. Hybridization competition experiments were employed to determine whether the populations of D-RNA molecules synthesized during two different portions of the mammalian cell cycle were completely different. No difference could be demonstrated suggesting that at least some of the same species of D-RNA were synthesized during both time periods examined. An investigation of the pattern of synthesis of the enzymes lactic dehydrogenase and fumarase in synchronized cells indicated that both enzymes were synthesized continuously. The possibility that some mammalian genes function continuously during interphase is discussed. © 1969.