Journal: BMC Developmental Biology
Article Title: Differential requirement for Dab2 in the development of embryonic and extra-embryonic tissues
Figure Lengend Snippet: Conditional targeting strategy and screening for homologous recombination of dab2 gene. (A) Schematic illustration of dab2 gene targeting strategy and gene deletion in mutant mice is shown. The targeting construct was made by inserting a neomycin resistance gene (Neo-R) flanked by Frt sites (closed triangles) between exon 4 and 5. LoxP sites (open triangles) were placed flanking exon 3 and 4. Correct homologous recombination of the targeting construct did not alter dab2 gene but allowed expression of Neo-R for selection of mutant ES clones. Following selection and verification, chimeric and then germline mutant mice were made from the mutant ES cells. The Neo-R cassette was excised by crossing with Flp expression mice to generate the floxed allele. The deletion of exon 4 removed a potential alternative translation start site, indicated as “ATG”. (B) Examples of PCR screening assay of neomycin resistant clones (#25-30) following transfection of linearized targeting construct and drug selection. Each clone was amplified separately for wildtype (886 bp) and recombinant allele (1714 bp, as predicted). Here, clone #28 was identified as positive. In the agarose gel: lane 1: Mw markers; lane 2: control mouse DNA; lane 3: KO construct; lane 4: control WT mix, no DNA; 5: control mix for mutant, no DNA; lanes 6 to 17, amplification using DNA template from clone #25 to 30. (C) Examples of targeted allele in selected clones (#1, #28, and #121). Here, clone #1 was found to lack the loxP1 site, whereas clones #28 and #121 contained all components: LoxP1, 1714 bp; LoxP2, 795 bp; Frt1, 635 bp; Frt2, 837 bp; and Neo, 617 bp.
Article Snippet: Each PCR fragment generated was amplified using cloned-Pfu DNA polymerase (Stratagene), which has a proofreading activity that results in high-fidelity DNA replication.
Techniques: Homologous Recombination, Mutagenesis, Mouse Assay, Construct, Expressing, Selection, Clone Assay, Polymerase Chain Reaction, Screening Assay, Transfection, Amplification, Recombinant, Agarose Gel Electrophoresis