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. 2018 Nov 1;103(5):752–768. doi: 10.1016/j.ajhg.2018.10.006

Figure 4.

Figure 4

Cortical-Specific Knockout of Nfib Results in an Enlargement of the Cortex

(A) Representative brains of homozygous Nfib conditional littermates with Cre (conditional knockout; cKO) and without Cre (wild-type; WT) at postnatal day (P) 10. The cKO brain expresses tdTomato red fluorescent protein as a reporter for Cre-mediated Nfib knockout. Scale bar is 5 mm.

(B) Based on measurements of dissected brains from cKO and WT littermates, the cortical length and width were significantly increased in cKO compared to WT animals at P10, P15, P25, and P110. Error bars represent standard error and the significance was determined by a one-way ANOVA. P10, n = 8 for both groups; P15, n = 5 and 6; P25, n = 3 and 5; P110, n = 8 and 4 for WT and cKO, respectively. ∗∗∗p < 0.0005, ∗∗p < 0.005, ∗p < 0.05.

(C) Fast low-angle shot (FLASH) MRI images of the same P110 animals measured in (B) revealed no major changes of the overall brain structure of cKO brains compared to WT littermates. Scale bar is 2 mm.

(D and E) The overall length (red line) and surface area (purple) of the cortex normalized to the overall brain length (yellow) was increased. Similarly, the height of the cortex at the midline (green line in coronal section), as measured from the corpus callosum to the caudal tip of the brain and normalized to the total height (yellow line in coronal section), was also increased. Significance was determined by Welch’s corrected t test. n = 7 and 8. ∗∗∗p < 0.0005, ∗∗p < 0.005.

(F) Based on MRI, the volumes of the cortex and hippocampus (HP) increased more than 16%, while the volume of the other brain structures only slightly increased. Significance was determined by Welch’s corrected t test. n = 7 and 8. ∗∗∗p < 0.0005.

(G and H) Histological analyses of independent brains at P130 confirmed no major structural changes, including in cortical lamination. Scale bar is 1 mm.

(I) Similar to the measurements in MRI images, the cortical height at the midline was increased. Significance was determined by Welch’s corrected t test. P10, n = 4 and 6. ∗∗∗p < 0.0005. All error bars represent standard deviation.