Study of the role of the δ-δ' interaction in RmInt1 excision in vivo. (A) Schematic diagram of domain dI focusing on the region containing the EBSs (1, 2 and 3), δ and δ' elements, which are shown in bold typeface. (B) Autoradiograph of the products generated in the primer extension assay. Modifications to the δ and δ' wild-type elements in the different mutants are indicated in bold typeface. (C) Diagram of the double plasmid homing assay performed showing Intron donor, recipient plasmids containing RmInt1 target sites (E1+E2), and homing products. Relevant restriction sites and the sizes of DNA fragments used as diagnostic of homing are indicated (D) Southern blot obtained in homing assays between derivative donor plasmids (pKG2.5 with modifications of the aforementioned elements) and the wild-type recipient plasmid pJB-20/+5 containing the homing site or a mutant (pJB-20/+5; IBS3 G) shown in bold typeface. An RmInt1 specific probe was used, after the EcoR I digestion of plasmid DNA pools for the detection of donor and homing products.