Comparison of Purine Metabolism in Suspension Cultured Cells of Different Growth Phases and Stem Tissue of Catharanthus roseus

The overall metabolism of [8-14C]adenine, [8-14C]adenosine, [8-14C]guanine, [8-14C]hypoxan- thine and [8-14C]inosine in suspension cultured cells of the lag, cell division, cell expansion and stationary phases and stem tissue of Catharanthus roseus was studied. On a fresh weight basis, absorption of all purine bases and nucleotides by the cultured cells was 10-400 times higher than that by the stem tissue. The conventional pathways of purine salvage and degradation were operative both in the cultured cells and stem tissue. [8-14C]Adenine and [8-14C]adenosine were extensively salvaged to nucleotides and nucleic acids in both the cultured cells and the stem tissue. [8-14C]-Guanine, [8-14C]hypoxanthine and [8-14C]inosine were incorporated into either salvage products (nucleotides and nucleic acids) or degradation products (CO2, allantoin and allantoic acid) of cultured cells and stem tissue. The highest incorporation rate expressed as a percentage of absorbed 14C into the degradation products was observed in the lag phase (12h-old) cultured cells. Incorporation of all precursors into nucleotides and bases was much higher in the stem tissue than in the culltured cells.