Figure 5. Efnb3 is expressed in CTIP2 +projection neurons.

(a) Representative cells within WT mouse cortex labeled by RNAscope ISH for CTIP2 mRNA (Bcl11b), SATB2 mRNA (Satb2), and eB3 mRNA (Efnb3). Scale bar, 3 μm. (b) Quantification of the number of RNAscope ISH eB3 puncta per cell across the indicated cell types (CTIP2+, n = 72; CTIP2+/SATB2+, n = 69; SATB2+, n = 93; F (2, 231)=9.332, p=0.0001, one-way ANOVA, ***p=0.0004, **p=0.0026 *, Tukey’s post hoc.) (c) Representative image of a tdTomato+/CTIP2 +cell in MADM cortex co-labeled with CTIP2 and SATB2 antibodies. Scale bar, 10 μm. (d) Analysis of apical dendrite width in subgranular neurons expressing CTIP2 and/or SATB2. Most neurons expressing CTIP2 have large (>1.6 μm) dendrites.

Figure 5—figure supplement 1. Schematic of recombination in eB3 MADM mice.

(a) Interchromosomal recombination in eB3 MADM mice generates fluorescently labeled cells of known eB3 genotype. Cre-mediated recombination in G2 phase followed by segregation of chromatids into daughter cells generates a wild-type (tdTomato+) and an eB3 null (EGFP+) cell (G2-X segregation), or one unlabeled and one double-labeled cell with unaltered genotype (G2-Z segregation). Recombination in G1 or G0 phase results in a double-labeled cell with unaltered genotype. Adapted from Espinosa et al., 2009.

Figure 5—figure supplement 2. Controls for RNAscope ISH.

(a) Representative three color RNAscope ISH images from WT and Efnb3^-/- mouse cortex, showing reduced eB3 probe signal in CTIP2 + cells (CTIP2 + and CTIP2+/SATB2 + included) within Efnb3^-/- cortex. Scale bar, 3 µm. (b) Quantification of Efnb3 expression in the indicated cell types in WT and Efnb3^-/- cortex (WT CTIP2+, n = 141; WT SATB2+, n = 93; KO CTIP2+, n = 236; KO SATB2+, n = 86 F (3, 552)=14.39, p<0.0001, one-way ANOVA, ****p<0.0001, Tukey’s post hoc). (c) Distribution of Efnb3 puncta numbers in CTIP2 + cells (N = 84, bin size = 4). Cells with less than five puncta were excluded.