CHANGING NUCLEOTIDE PATTERN OF SYCAMORE CELLS DURING CULTURE IN SUSPENSION

The nucleotide components of cells of Acer pseudoplatanus L., grown in a large-scale suspenion culture (4·5 1.), have been examined and fluctuations in their individual concentrations assessed during the three phases of growth, i.e. lag phase, period of rapid cell division, and stationary phase. Initially, the predominant nucleotide is ATP but, by the end of the lag phase, its place has been taken by UDP-glucose. The most marked change in nucleotide pattern occurs between days 0 and 4 (lag phase) when a relatively large increase is observed in the concentration of all the components. During this stage, there is a 46-fold increase in UDP-glucose concentration and a 7-fold increase in that of UTP. By day 8 (period of rapid cell division) the individual concentrations of ATP, the guanosine nucleotides, UTP and UDP-glucose, have started to fall and are then at positions intermediate to those of days 0 and 4. In contrast, the NAD concentration shows a marked increase at day 8. Traces of a UDP-uronic acid, tentatively identified as UDP-galacturonic acid, and an unidentified guanosine nucleotide of the type GDP-X were observed. The results reveal a high peak of metabolic activity in Acer suspension cultures immediately before the onset of the period of rapid cell division. No nucleotides could be detected in the culture medium at the end of the 3-week growth period. © 1970.