Fig. 5.

De novo TAG biosynthesis by direct bicarbonate incorporation and via PLs. (A) De novo synthesis of PLs and of TAG during each day of N deprivation. Parallel cultures of D. tertiolecta were pulse-labeled for 24 h with [¹⁴C]bicarbonate during different days of N deprivation as described in Fig. 4. At the end of labeling, cells were washed, lipids were extracted and fractionated to PLs and TAG, and the level of ¹⁴C in each fraction was determined and expressed in nmol C 10⁶ cells⁻¹ (means ±SD of three independent experiments). (B) Formation of TAG from PLs produced during the first day of N deprivation. Dunaliella tertiolecta cells were labeled with [¹⁴C]PlA during the first 24 h of N deprivation. The cells were washed and transferred to fresh N-deprived medium. Each day samples were fractionated and analyzed. Results are expressed in pmol PlA incorporated per day per 10⁶ cells (means ± SD of three independent experiments). (This figure is available in colour at JXB online.)