Metabolic Functions of Myo-inositol II. EFFECT OF INOSITOL DEFICIENCY ON THE METABOLISM OF NJCLEIC ACIDS OF MAMMALIAN CELLS IN TISSUE CULTURE*

We have previously reported (1) that myo-inositol deficiency in yeast results in a marked alteration of the chemical composition of the cell wall, as a consequence of which cell division is inhibited. The main change observed in those studies involved the polysaccharide fraction of the cell walls and it was inferred that inositoll deficiency interferes with the normal biosynthesis of cell wall polysaccharides. Since inositol is required for the maintenance and multiplication of mammalian cells grown in vitro (2), and since the cell walls of mammalian cells do not contain the polysaccharides found in yeast cell walls, it would appear that inositol may exhibit different functions in mammalian cells from those observed in yeast. The present report deals with the effects of inositol deficiency on the metabolism of nucleic acids of mammalian cells in tissue culture. It has been found that inositol deficiency causes a marked decrease of the acid-soluble nucleotides and the ribonucleic acid of the cells, as well as a significant decrease of the rate of incorporation of radioactive carbon of glucose into the guanine of ribonucleic acid. The amount and the specific activity (c.p.m. per pmole) of the acid-soluble nucleotides, the ribonucleic acid bases, and the deosyribonucleic acid bases have been determined at various periods with cells grown with and without inositol.