Stage-dependent mRNA expression of parasite antioxidant enzymes (A) and Hsps (B) in parasites growing in normal RBCs. Schizont stage parasitized normal RBCs separated on mannitol-containing discontinuous Percoll gradient (parasitaemia >95%) were mixed with normal RBCs, suspended in growth medium to start synchronous cultures (time 0). Six h after reinfection, parasite ring stages were isolated, washed three times and incubated in growth medium. At 13 (early ring stage), 16 (late ring stage), 19 (early trophozoite stage), 28 (late trophozoite stage) and 46 (schizont stage) h after reinfection, 200 μl of parasitized RBCs were lysed and RNA extracted. Changes in mRNA expression were measured using qRT-PCR. For details, see Methods. Results are presented as -fold increase over the mRNA level at early ring stage measured 13 h after reinfection using the 2-ΔΔCt method. Mean values ± SEM (vertical bars), n = 1–4.