The plateau phase of growth of the L-M strain mouse cell in a protein-free medium : III. The effect of added glucose on protein and nucleic acid synthesis and on carborhydrate utilization

Abstract

The addition of radioactive glucose to suspension cultures of L-M strain mouse cells during the plateau phase has been shown to extend the duration of this period from the normal 48-72 hr to 144-240 hr. Supplemental carbohydrate serves both as an energy source, as detected by the production of radioactive lactic acid and carbon dioxide, and as a precursor for nucleic acid and protein synthesis during this period. On the basis of the specific activities of the nucleic acids and proteins recovered from both the cells and the medium, possibilities of synthesis of multiple proteins and of extracellular RNA are discussed. The addition of radioactive homologous nucleic acidprotein fractions to culture in logarithmic growth is shown to reduce the mean generation time by 50 per cent. The recovery of 12 to 13 per cent of the radioactivity in these same fractions isolated from the cells at the end of logarithmic growth suggests that cells have the potential for re-utilization of cellular material release into the medium from other cells in the population.