Fig. 1

F8 Seamless vector production and targeting strategy for genomic recombination of seamless vector with endogenous attH4x sites in LINE-1. a A pictorial representation of phage λ-mediated intramolecular in vitro/in vivo recombination between attH4X and attP4X (both present in the parental substrate vector) generating seamless vector EF1α-F8-IRES-NeoR with a recombinant attL4X junction, which can subsequently intracellularly recombine with attH4X (present in human genome LINE-1). Successful integration will form attL4X (left) and attH4X (right) recombinant sites flanking the cassette EF1α-F8-IRES-NeoR at the site of integration. b Agarose gel electrophoresis of parental substrate vector and F8 seamless vector demonstrating their migration and quality. The supercoiled substrate vector (13,267 bp) migrates at ∼ 8 kb linear control DNA and supercoiled F8 seamless vector (10,170 bp) migrates at ∼ 5.7 kb in a gel containing ethidium bromide. c A schematic representation of λ -mediated intracellular recombination of attP4X (present in the parental substrate vector) with attH4X (present in human genome LINE-1). Successful integration will form attL4X (left) and attR4X (right) recombinant sites flanking the cassette EF1α-F8-IRES-NeoR along with bacterial sequences at the site of integration