Fig. 2.

In the absence of extracellular isoleucine, Plasmodium falciparum completes the cell cycle at a retarded rate. a Synchronous young ring NF54 parasites were cultured in normal culture medium, or culture medium lacking isoleucine (No Ile) for 72 h. “Recovery” denotes parasites that were transferred back to normal medium after deprivation for 72 h of regrowth (t-test, error bars represent standard error, n = 3). b Synchronous cultures of NF54 parasites were initiated with Percoll-isolated late schizonts in either normal medium or medium lacking isoleucine. Progression of each culture was tracked every 8 h for 136 h. Images are representative of the major forms observed at each time point. “Generation” represents the time required to transition from ring through the cell cycle to ring again. c Flow cytometry was used to track the DNA content of the cultures over the 136-h time course. Dotted-line plots represent the proportion of parasites with a 1C DNA content. Isoleucine-deprived parasites proceed through the cell cycle at approximately half the rate as those in normal medium. d Parasitaemia of cultures across the 136-h incubation. e Flow cytometry was used to determine the average DNA content of SYBR Green I-stained parasites at the first schizont-enriched time point (40 h for normal medium; 88 h for isoleucine-deprived medium; cf. Fig. 2b) for each treatment across the 136-h time course. “C” refers to the number of genome complements per cell