Figure 2. T. gondii tachyzoites catabolize glucose in a complete TCA cycle.

(A) Infected HFF or egressed tachyzoites (ET) were suspended in medium containing either ¹³C-U-glucose or ¹³C-U-glutamine for 4 hr. Intracellular tachyzoites (IT) were isolated from host material prior to metabolite extraction. Incorporation of ¹³C into selected polar metabolites and fatty acids (derived from total lipid extracts) was quantified by GC-MS and levels (mol percent containing one or more ¹³C carbons) after correction for natural abundance are represented by heat plots. (B) Egressed tachyzoites were incubated in full medium containing either ¹³C-U-glucose (upper panel) or ¹³C-U-glutamine (lower panel) in place of naturally labelled glucose or glutamine, respectively. Culture medium was collected at 6, 12 and 24 hr and analysed by ¹³C-NMR. Rates of utilization of each carbon source are shown in black, while rate of secretion of lactate (Lac), CO₂ (detected as H¹³CO₃), glutamate (Glu), alanine (Ala), aspartate (Asp) and succinate (Suc) are shown in grey. See also Figure S2.