Fig. 1. Transfection of Nkx2.1^-/- slices with Nkx2.1 cDNA results in rescue of interneuron phenotypes. (A-D) Schematic showing slice electroporation and transplantation paradigm. (A) The Nkx2.1 domain is shown in the MGE of an E12.5 wild-type (wt) mouse embryo slice. The MGE^*, a region that expresses a truncated Nkx2.1 transcript (Sussel et al., 1999), is shown in the slice from an Nkx2.1 mutant embryo. (B) This MGE^* region is targeted for electroporation, and after 1 day in vitro (DIV) the region is dissected out, dissociated and transplanted (C,D) directly into the neocortex of neonatal pups (as in H-N), or plated onto a high-density culture of neonatal cortical cells [as in Xu et al. (Xu et al., 2004); see Fig. S2 in the supplementary material]. (E,F) Coronal sections of a slice from an E12.5 wt embryo that was electroporated with pNkx2.1-GFP, maintained 1DIV, then fixed and examined for GFP fluorescence (E) and NKX2.1 immunolabeling (F). The right-hand, electroporated side of the slice has extensive ectopic NKX2.1 expression, whereas only native NKX2.1 expression is seen on the left-hand side of the slice (arrow in F). (G) A slice from an Nkx2.1^-/- embryo was electroporated with pNkx2.1-GFP. After 1DIV, cells from the MGE^* (outlined in white) were transplanted into the cortical plate of a neonatal pup and then examined at postnatal day 30 (P30) in 40 µm coronal sections. (H) Transplanted GFP-expressing cells scattered through the medial cortex. (I-N) Examples of co-labeling for GFP and parvalbumin (PV; I,J), somatostatin (SST; K,L), and neuropeptide Y (NPY; M,N). In control experiments with pGFP vector, almost no cells expressing any of these markers are detected after transplantation of Nkx2.1^-/- MGE^* progenitors (Table 1). MGE, medial ganglionic eminence; LGE, lateral ganglionic eminence; Ctx, cerebral cortex. Scale bars: 100 µm in G,H.