Figure 1. Abnormal body size, head shape and walking posture of homozygous Dscam^del17 mutant mice.

(A) The domain structure of DSCAM. The Dscam^del17 mutation results in a truncated protein at the second FNIII domain. (B) Genotyping of Dscam^del17 mutant mice. PCR with the specific primers led to detection of a 170 bp band in wild type mice (panel 1), a 133 bp band in homozygous Dscam^del17 mutant mice (panel 3), and both bands in heterozygous Dscam^del17 mutant mice (panel 2). (C) Physical characteristics of Dscam^del17 mutant mice. At 3 weeks old, homozygous Dscam^del17 mutant mice show delayed development, exhibiting smaller body size (C3), dome-shaped head, small ears and closed eyes (C2) as compared with their wild type littermates (C1). Moreover, at this age, wild type mice were able to walk whereas homozygous Dscam^del17 mutant mice were not (scale bar: 1 cm) (D) Dome-shaped head of a homozygous Dscam^del17 mutant mouse (D1) as compared with that of the wild type mouse (D2) (scale bar: 0.5 cm) (E) Change in locomotion. The body sizes of homozygous Dscam^del17 mutant mice gradually increased and became similar to that of wild type mice. By 2 months of age, homozygous Dscam^del17 mutant mice (E1) were almost the same as the wild type mice in size (E2). As compared with wild type mice (E2), homozygous Dscam^del17 mutant mice showed abnormal locomotion by walking on their toes with tetanic hind limbs bent back and down-curved tails (E1) (scale bar: 2 cm) [Wt, wild type; het(+/−), heterozygous Dscam^del17 mutant mice; hm(−/−), homozygous Dscam^del17 mutant mice].