Changes in transcript expression levels during the formation and activation of P. falciparum gametocytes. (A) Diagnostic RT-PCR demonstrated the presence of stage-specific transcript in the asexual blood stages of the gametocyte-less strain F12 (F12 ABS) as well as in immature (stage III/IV) and mature (stage V) non-activated gametocytes (GC) and in gametocytes at 30 min p.a. in vitro. ama-1, marker for ABS; pfccp2, marker for GC. Transcript of gene hdac1 was detected in all stages investigated, while no hdac1-specific PCR product was detected in samples lacking reverse transcriptase (RT). (B) Real-time RT-PCR analysis showed changes of transcript expression of 27 of the SSH-identified genes between ABS, immature and mature non-activated GCs and in GCs at 30 min p.a. in vitro. Transcript expression levels were calculated by the 2-ΔCt method; the threshold cycle number (Ct) was normalized with the Ct of the gene encoding for seryl tRNA synthetase as reference.