FIGURE 1.

Generation of SMS2 KO mice. A, schematic of targeted disruption of SMS2. The top illustration is a wild type allele; the middle shows the targeting construct with the neomycin-resistant gene (PGK-neo), diphtheria toxin A chain gene (DT-A), and nuclear localization signal-LacZ (NLS-LacZ). The bottom illustration shows the allele mutated by homologous recombination. Closed and open arrowheads are corresponding to the primer position to detect wild type and knock-out (KO) alleles, respectively. B, confirmation of homologous recombination by long accurate-PCR using the primers indicated in A. The ladder is 1-kb DNA ladder (M). The primer sets of a and b and d and f were for WT allele; a and c and e and f were for KO allele. HE, heterozygote. C, RT-PCR was performed for the expression of SMS1, SMS2, and GAPDH in WT and SMS2 KO mice. D, amounts of SM, Cer, and PC were determined as described under “Experimental Procedures.” Data are presented as the mean ± S.D. of five distinct mice. *, p < 0.05.