Fig. 8. Gap repair. (A) Recombineering-mediated gap repair. Two homology arms, located at the 5' (Left, L) and 3' (Right, R) end of a genomic region of interest present in a BAC, are cloned into the desired plasmid. Restriction enzyme-mediated linearization between both homology arms and subsequent transformation in bacteria competent for recombineering functions allow the selective retrieval of the desired fragment from the BAC into the plasmid through gap repair. The resulting plasmid can be used for P transposase- (5'P and 3'P element termini) or C31 integrase-mediated transgenesis (attB site). (B) In vivo gap repair. Two homology arms, located at the 5' and 3' ends of a genomic region of interest, are cloned within a P element. After P transposase-mediated germ line transmission, the transgene is linearized in vivo between both homology arms using the meganuclease I-SceI, potentially resulting in the selective capture of the desired fragment from a wild-type chromosome through homologous recombination-mediated gap repair.