Fig. 2. Asp racemase distribution and its tropic effect.

Mouse Asp racemase was expressed in adult hippocampus and (a) the racemase expression was locally suppressed by short-hairpin RNA (shRNA) against the racemase (shRNA-DR) in newborn neurons (green fluorescence) while control shRNA did not suppress the racemase expression in newborn neurons (red fluorescence); hippocampus cells (blue) were stained with 4′,6-diamidino-2-phenylindole. Scale bar, 50 μm. (b) Survival rate of newborn neurons is compared with shRNA-DR treatment vs. shRNA-control treatment. Neurons contain both shRNA-DR and control shRNA expressed yellow fluorescence. *, P <.05; n = 4 mice for each time point, ANOVA. (c) Immunohistochemical measurement of an Asp racemase in the cerebral ganglion from Aplysia capable of racemizing both D-Asp and D-Ser. The C- and F-cluster neurons are indicated by the area enclosed in the dotted line. (d) CE analysis on C- and F-cluster neurons showed high amounts of D-Asp and D-Ser. Separation condition: 27 kV normal polarity was applied to an uncoated fused-silica capillary (80 cm total length, 70 cm effective length, 75 μm i.d./360 μm o.d.) filled with separation buffer. The separation buffer for Asp enantiomers consisted of 40 mM β-cyclodextrin and 60 mM sodium deoxycholate in 200 mM borate buffer, pH 9.5. The Ser enantiomer separation buffer consisted of 10 mM γ-cyclodextrin and 50 mM sodium dodecyl sulfate in 75 mM borate buffer, pH 10.5. Panels a and b from (Kim et al. 2010) are used with permission, copyright 2010 National Academy of Sciences, U.S.A.; panels c and d from (Wang et al. 2011) are used with permission, © the American Society for Biochemistry and Molecular Biology.