FIGURE 1.

Relative and absolute quantities of ¹³C-labeled glycerol from complex lipid hydrolysis after labeling with [U-¹³C]glucose during stress-free growth and after 1 week of label-free nitrogen starvation. Data are shown for the glycerol moieties of three lipid classes separated by polarity, TG, GL, and PL after prelabeling with ¹³C and a subsequent 1 week of growth in label-free nitrogen-free media. Isotopic distributions from GC-MS analysis of derivatized glycerol were used to generate the amount of unlabeled, single ¹³C-labeled, double ¹³C-labeled, and totally labeled glycerol as a percentage of the total quantity (A) and as a percentage of the extracted dry weight of algae (B). Error bars represent S.D.; n = 3.