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. 2007 Aug 31;8(10):959–965. doi: 10.1038/sj.embor.7401063

Figure 3.

Figure 3

Expression of luciferase, bsd and the var gene family in transfected parasite lines. (A) Schematic map of pVLH/IDH-FP. (B) Schematic map of the var gene PFB1055c in the transgenic parasite line B12E3. (C) Results confirming simultaneous transcription of two var promoters in stably transfected parasite lines. Upper panel: B12E3 stably transfected with pVLH/IDH-FP and grown in the absence of blasticidin. Both the endogenous var gene PFD1015c and luciferase are highly expressed, whereas all other var genes are silent. Lower panel: the same parasite line, grown for several weeks under blasticidin pressure. Expression switched to the recombinant var (PFB1055c) containing the bsd-resistant gene, which was then transcribed in a mutually exclusive manner. However, the expression level of the luciferase gene being driven by an ‘unpaired' var promoter remains unchanged. (D) Simultaneous protein expression by two var promoters in stably transfected parasite lines. Luciferase is highly expressed in transfected parasites grown with (lower panel) or without (upper panel) blasticidin pressure. Stable episomes were maintained using WR99210 (WR) pressure to select for expression of the human dihydrofolate reductase gene (hdhfr).