Notch3 controls radial glia quiescence and stemness. (A-B) Detection of the three progenitor cell types of the pallial VZ in a wild-type 7 dpf larva. (C) Progenitors of the pallial VZ in a 7 dpf notch3−/− larva. (A,C) Double immunocytochemistry for the RG marker BLBP (green) and the proliferation marker PCNA (magenta) on a telencephalic cross-section (counterstained with DAPI). (A′,C′) High magnification of the areas boxed in A,C. qRG, green arrow; aRG, white arrow; aNPs, magenta arrow. (B) Schematic representation of the main neurogenic cascade in the post-embryonic pallium, with diagnostic markers. At least some RGs transit between the qRG and aRG states (Chapouton et al., 2010). N, neurons. (D) Total number of RGs (qRGs+aRGs) counted per 100 µm of VZ on cross-sections at mid-pallial levels. There is no significant difference between stages and between genotypes within the period considered. (E) Proportion of aRGs within the total RG population between 7 dpf and 10 dpf compared in wild-type and notch3−/− sibling larvae. *P<0.05 after Holm's correction, otherwise non-significant. (F) Total number of BrdU-positive RGs (qRGs+aRGs) counted per 100 µm of VZ on cross-sections at mid-pallial levels between 7 dpf (t0, no chase) and 10 dpf (3 days of chase), compared in wild-type and notch3−/− sibling larvae. (G,H) Proportion of the different neural cell types (qRGs, aRGs, aNPs, neurons) within the BrdU-positive population following BrdU pulse application at 7 dpf (t0, no chase) and after 1, 2 or 3 days of chase (i.e. with analyses at 8, 9 and 10 dpf, respectively), compared in wild-type (G) and notch3−/− (H) sibling larvae. Black lines and asterisks: statistics with Holm's correction for multiple comparisons. *P<0.05, **P<0.01. Red lines and asterisks: LSD test for comparisons between 2 and 3 days of chase. The proportion of aNPs decreases significantly and the proportion of neurons increases significantly, in notch3−/− mutants only (P=0.007 and P=0.002, respectively). Green asterisks: LSD test for comparisons between wild-type and notch3−/− at 3 days of chase. The proportion of neurons is significantly increased in notch3−/− mutants versus wild type (P=0.02). Scale bars: 10 µm in A,C; 20 µm in A′,C′. (D-F) n=6-11 telencephali per condition.
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