FIGURE 3.

A, the effect of thiamine depletion and oxythiamine exposure on long-term [6-¹³C]glucose labeling of P. falciparum-infected and uninfected erythrocytes (uRBC). NF54 and pdh e1α- parasite strains were grown under standard culturing conditions for 48 h in standard RPMI, thiamine-free RPMI, and thiamine-free RPMI with 200 μm oxythiamine. Enriched infected erythrocytes were then incubated for 3 h in equivalent media containing 1:1 [6-¹²C]glucose:[6-¹³C]glucose. The top panel represents the fractional isotope labeling of pyruvate, and the bottom panel represents acetyl-CoA isotope labeling. Signals were corrected for natural abundance and maximal theoretical enrichment for equal ¹²C:¹³C labeling. The percentages of 3-¹³C or 2-¹³C label (pyruvate and acetyl-CoA, respectively) of the total metabolite pools are presented for each condition as the mean ± S.E. from n = 3. B, 3 h [1-¹³C]pyruvate labeling of P. falciparum-infected erythrocytes. Enriched P. falciparum-infected and uninfected erythrocyte suspensions were added to RPMI containing 10 mm [1-¹³C]pyruvate in a 1:1 ratio (or standard RPMI for time = 0) giving a final concentration of 5 mm [1-¹³C]pyruvate. Acetyl-CoA labeling was measured by LC-MS presented as the percent of 1-¹³C label of the total acetyl-CoA pool (corrected for natural abundance). The purple asterisk denotes statistical significance of [1-¹³C]acetyl-CoA between time = 0 and 1 and 2 h of [1-¹³C]pyruvate incubation. Data are presented as the mean ± S.E. from n = 3 experiments.