Figure 7

Effect of heat shock on EhrabB transcription. (A) Schematic representation of the EhrabB promoter region and its putative cis-acting consensus sequences (boxes). Arrows indicate the transcription initiation sites. (B) The 683 bp DNA fragment from the 5'-flanking region of EhrabB was cloned upstream of the cat reporter gene into the pBSCAT-ACT vector. E. histolytica trophozoites were transfected with this construction and incubated at 37°C for 48 h. Then, trophozoites were incubated for 2 and 4 h more at 37°C or at 42°C and CAT activities were determined. Activities are relative to that obtained with the actin promoter gene at 37°C, used as positive control. Each bar corresponds to the average of CAT activities ± S.D. representative of three independent experiments performed by duplicate. (C) Real-time RT-PCR assays using RNA from trophozoites grown at 37°C (A) or after 4 h of heat shock treatment (A-HS) and specific primers for EhrabB. Amplification of the E. histolytica 18S rRNA was used as normalizer.