[1, 2-¹³C]-acetate metabolism monitored by NMR for eight days shows TAG accumulation in cells: a starvation response.

<p>Bright field counts of cells in mixo- <i>versus</i> heterotrophic incubation conditions over a period of eight days. Mean/SD were retrieved from three independent experimental measurements. (B–C) Assimilation kinetics of acetate by <i>C. reinhardtii</i> followed by TAG accumulation in the cells, as studied by recording proton decoupled 1D [¹³C]-NMR spectra, during (B) heterotrophy and (C) mixotrophy, at different time points. The spectra were recorded over a period of eight days, following the addition of [1, 2-¹³C]-acetate to the TP medium. (D) Total lipid estimation by phosphorvanillin assay of cells in mixo- <i>versus</i> heterotrophic incubation conditions over a period of eight days. Values are mean of three independent experiments ± SD. (E) Confocal image of lipid body formation due to TAG accumulation detected by BODIPY staining and chloroplast autofluorescence of the cells on different days of growth in mixotrophy and heterotrophy. Bar corresponds to 5µm. (The signs *, ** represent methyl and carboxyl peaks of [1, 2-¹³C]-acetic acid, and the signs⁺and⁺⁺represent bicarbonate and CO₂, respectively).