Sizn1 is a novel gene expressed in the ventral forebrain. (A) Schematic diagram of the Sizn1 protein and the amino acid sequence alignment of Sizn1 and Sizn2. The Zn finger motif, nuclear localization sequence (NLS), and MA-homologous domain are highlighted. The unique C-terminal sequence of Sizn1 used as the peptide antigen is also shown. (B) Northern blot analysis with E12.5 dorsal (D) and ventral (V) total RNAs shows that Sizn1 is expressed ventrally, similarly to the known ventrally expressed Dlx5 gene. GAPDH serves as a loading control. (C) Adult tissue Northern blot analysis shows that Sizn1 is expressed in the adult brain and testis. (D, E) Whole-mount in situ hybridization for Sizn1 in the embryonic mouse brain. Sizn1 expression is restricted to the ventral region of the forebrain, including the septum, amygdala, and caudal putamen. (D) Lateral view of an E12.5 telencephalon. (E) Coronal view of an E14.5 forebrain at the level where both the posterior telencephalon and anterior diencephalon can be recognized. Ncx, neocortex; Str, striatum; T, thalamus; H, hypothalamus; A, amygdala.