Assimilation kinetics of [1, 2-¹³C]-acetate in heterotrophy.

<p>(A) Assimilation kinetics of acetate by <i>C. reinhardtii</i>, as studied by recording proton decoupled 1D¹³C-NMR spectra, during heterotrophic growth at different time points after adding the [1, 2-¹³C]-acetate to the TP growth medium (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0106457#pone.0106457.s001" target="_blank">Fig. S1</a>). The spectra from the same experiment are stacked for representation. Peaks at 125.48 and 161.01 ppm show CO₂^aq and bicarbonate, respectively. (B) Quantitative analyses of [¹³C]-methyl-peak intensity of acetate and metabolites (bicarbonate and CO₂^aq) at different time intervals during heterotrophy. Peak intensities (area under the peaks) were normalized with respect to the 0 hr data for acetate. Values are mean of three independent experiments ± SD. (C) Proton decoupled 1D [¹³C]-NMR spectra recorded on 700 MHz with TXO probe optimized for direct [¹³C]-detection at 298 K with heterotrophic cells grown in dark for 24 hrs in TP growth medium containing [1, 2-¹³C]-acetate. The peaks 1 and 3 detected at 61.93 and 72.48 ppm, respectively, represent carbons from glycerol (J_CC = 41 Hz and J_CH = 142 Hz) while peaks 2, 4, 5, 6 and 7 at 62.97, 72.88, 74.79, 78.32 and 101.06 ppm, respectively, represent carbons from starch. (The signs * and ** represent methyl and carboxyl peaks, respectively, of [1, 2-¹³C]-acetic acid, and the signs⁺and⁺⁺represent bicarbonate and CO₂^aq peaks, respectively).