Simultaneous replacement of consecutive ech1 and ech2 genes by another MS/GW construct pDEST/ ech _Neo-GAPDH. A) Diagram of ech1, ech2 and Neo-GAPDH 3'UTR genomic loci in ech+/-/Neo parasites. B) PCR genotyping analysis of: no template control (water); ech+/-/Neo (ech+/-) and WT CL (WT). See additional file 3: Table S5 for nucleotide sequences of primers. C) Southern blot analysis of WT CL (WT) and ech+/-/Neo (ech+/-) digested with EcoRI and hybridized with Neo CDS. Diagram not to scale. Numbers are sizes (bp) of expected products.