FIGURE 1.

Generation of Mtdh knock-out mice by targeted deletion of exon 3. A, promoterless targeting cassettes for the generation of a “KO first allele” in C57BL/6N embryonic stem cells were used to target Mtdh exon 3, an exon common to all transcript variants that, when deleted, creates a frameshift mutation. The KO first allele produced reporter-null alleles following subsequent exposure to site-specific recombinases Flp and Cre. B, representative genotyping of litters obtained by crossing Mtdh^+/− mice. Mtdh^+/+: lanes 3 and 6; Mtdh^+/−: lanes 1, 2, and 4; Mtdh^−/−: lane 5. M, molecular weight markers. C, Mtdh expression in liver, brain, and spleen lysates from Mtdh^+/+ and two different Mtdh^−/− mice, denoted as 1 and 2. Arrowheads indicate full-length Mtdh and ubiquitinated (Ub) Mtdh. D, representative images of testes from WT, heterozygous, and homozygous Mtdh exon 3-deficient adult male mice. E, representative images of Mtdh expression by immunohistochemistry in testes from Mtdh^+/+ and Mtdh^−/− mice.