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. Author manuscript; available in PMC: 2013 Apr 2.
Published in final edited form as: J Mol Biol. 2008 Jul 16;382(2):288–297. doi: 10.1016/j.jmb.2008.07.015

Figure 1.

Figure 1

Transcriptional repression of endogenous var genes by forced expression of multiple episomal var promoters. (A) Selection for parasite populations that carry the episome pVBH using increasing concentrations of blasticidin. The number of generations to reach 5% parasitemia increases in correlation to the increase in blasticidin concentration. (B) Parasite populations carry increasing copy numbers of pVBH with respect to blasticidin pressure. The number of bsd copies measured by Q-RT-PCR using gDNA as template is presented for each of the parasite populations grown under different concentrations of blasticidin. (C) bsd expression is correlated with the number of copies of pVBH. Total bsd expression was measured by Q-RT-PCR using cDNA as template from each of the parasite populations carrying increasing copy numbers of pVBH. Total expression is presented as relative copy numbers with respect to the control housekeeping gene seryl-tRNA synthetase (PF07_0073). (D) Transcriptional repression of the endogenous var PFD1005c in parasite populations expressing high copy numbers of pVBH. Expression levels of the active var gene PFD1005c and the silent var gene PFD1015c are presented for each of the parasite populations grown under different blasticidin concentrations with respect to the 3 control housekeeping genes: P60 - seryl-tRNA synthetase (PF07_0073), Arg - arginyl-tRNA synthetase (PFL0900c) and Glu -glutaminyl-tRNA synthetase (PF13_0170), (* significant down regulation, F = 10.49, P < 0.01).