[Purine metabolism in cultured Drosophila melanogaster cells: adenosine utilization]

14C-adenosine is incorporated very little inot nucleic acids of Drosophila cells cultured in a medium free of foetal calf serum. The greater part of the radioactivity is recovered in inosine and hypoxanthine. These results suggest that the principal pathway of ultilization of adenosine is not mediated by adenosine kinase. Adenosine is rapidly deaminated to inosine by adenosine deaminase, and cleaved to hypoxanthine by inosine phosphorylase. Inosine and hypoxanthine not being substrates for Drosophila cell lines, are released into the culture medium.