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. 1997 Jul 22;94(15):8093–8098. doi: 10.1073/pnas.94.15.8093

Figure 1.

Figure 1

Schematic diagram of the targeted disruption of the TNF gene in mice. (A) Structure of the linked wild-type LT-α, TNF, and LT-β genes. Solid boxes indicate exons and restriction sites are indicated as follows: A, AvrI; E, EcoRI; B, BamHI; H, HindIII; S, StuI. (B) Targeting construct and (C) targeted TNF gene. Targeting results in the insertion of a PGK-neo cassette and acquisition of a novel BamHI site as indicated. The location of the Southern probes for TNF (TNF), PGK-neo (NEO), and LT-α (LT) genes are indicated. (D) Southern blot analysis of BamHI-digested genomic DNA probed with a TNF-specific probe demonstrates that the TNF gene (TNF) is disrupted by the insertion of the PGK-neo cassette yielding the wild-type 12-kb band only in TNF+/+ mice, the shorter 11-kb fragment only in TNF−/− mice, and both fragments in TNF+/− mice. (E) Southern blot analysis of BamHI-digested genomic DNA using a PGK-neo-specific probe demonstrates the predicted gene dosage effect (NEO) in TNF+/+, TNF+/−, or TNF−/− mice, and no other sites of integration. (F) Southern blot analysis of StuI-digested genomic DNA using an LT-α-specific probe demonstrates that the LT-α gene is not affected by integration of the targeting construct in TNF+/+, TNF+/−, or TNF−/− mice.