FIGURE 2.

Glutamine-derived carbon flux is induced in intracellular tachyzoites of the Δtggt1 strain. Fractional abundance of ¹³C atoms in the carbon pool of select metabolites from the indicated parasite strains incubated with 5 mm [U-¹³C]glucose and 2 mm glutamine or with 2 mm [U-¹³C]glutamine and 5 mm glucose. Intracellular parasites were labeled with either of the isotopes for 4 h (37 °C, 5% CO₂) and subjected to metabolomics analysis by GC-MS, as defined under “Materials and Methods” (mean ± S.E., n = 4 assays). Corresponding heat-maps and labeling of individual isotopomers are shown in supplemental Figs. S5 and S6, respectively. Statistical significance was done separately for each group compared with the parental strain using Student's t test (*, p < 0.05; **, p < 0.01; ***, p < 0.001).