Figure 1.

Strategy of the Spg7 knockout. (a) The top diagram shows the WT genomic map comprising the first three Spg7 exons (ex), the position of the two external probes, and the EcoRV sites used for Southern analysis. On the bottom is a schematic representation of the targeting construct and the resulting targeted locus. Following homologous recombination, the insertion disrupted part of the promoter region and the first two exons of the gene, comprising the initiation methionine codon and most of the mitochondrial leader sequence. (b) Southern analysis of the first litter using the 5′ probe. The WT fragment is 18 kb, whereas the fragment corresponding to the targeted locus is 10 kb. (c) RT-PCR analysis on total embryo cDNA using oligonucleotides spanning exons 3 and 4, which were not targeted by the deletion, demonstrates that the Spg7 transcript is lacking in knockout mice. (d) Western blot analysis on mitochondrial proteins isolated from spinal cords of WT and knockout mice shows the absence of paraplegin in Spg7–/– animals.