Figure 7.

¹⁴C content of putative intermediates of CA1P biosynthesis as a function of time, during and after exposure to ¹⁴CO₂. After photosynthetic induction, leaf segments were exposed to 0.1% ¹⁴CO₂ for 5 min, followed by 0.1% ¹²CO₂ (transition indicated by vertical dotted line). At the indicated times samples were removed and immediately frozen in liquid N. The presence of specific ¹⁴C-labeled metabolites was determined: ●, FBP; ▾, HBP; ▿, HMP; ○, hamamelose; and ■, CA. The data are divided into two parts (A and B) depending on the duration of the cold-chase. Assays at 5 min show the mean (±SD) of three independent samples (errors within boundaries of symbols not shown). An additional sample (Inset) was removed from the chamber after 15 min and kept in darkness in normal air for 7 h before freezing. The CA1P content (□) of this sample was also determined, after affinity purification and HPLC (20).