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Fig. S3
PVN stratification in eyeless larvae and Reelin signaling pathway member expressions in PVNs. Related to Figure 2.
(A) Confocal image of a transiently GFP-labeled PVN in an RGC-innervated tectum at 5dpf shown from the side, parallel to the skin to highlight the PVNs’ stratified laminar morphology.
(B) Confocal image of a transiently GFP-labeled PVN in an RGC-depleted tectum at 5dpf shown from the side, parallel to the skin to highlight the PVNs’ stratified laminar morphology.
(C) Frequency distribution of non-stratified PVNs and stratified PVNs without lamina targeting mistakes at 5-6dpf in RGC-depleted tecta (n=7 larvae) and the tectum of larvae of which the corresponding eye was removed at 2 dpf (n=12 larvae). We could not observe any difference between the two groups (k*2-chi-square test after Brandt-Snedecor, p = 0.9596) thus suggesting that PVN lamination defects seen in reln -/-, vldlr -/-,/sup> and dab1a -/- are not a consequence of prior RGC mis-targeting but are better explained by PVNs using Reelin signaling as guidance signal to identify single target lamina.
(D) Horizontal cross-section of a 3 dpf zebrafish tectum showing strong mRNA expression of the Reelin receptor vldlr in PVNs.
(E) Horizontal cross-section of a 3 dpf zebrafish tectum showing strong mRNA expression of the Reelin receptor lrp8 in PVNs.
(F) Horizontal cross-section of a 3 dpf zebrafish tectum showing mRNA expression of dab1a, an intracellular transducer downstream of Reelin receptors, in PVNs.
(G) Horizontal cross-section of a 3 dpf zebrafish tectum showing mRNA expression of dab1b, a paralog of dab1a, in PVNs.
(H-I) Confocal reconstruction of radial glia cells transiently labeled with the GFAP:GFP construct. Radial glia span the entire depth of the larval zebrafish tectum, from the ventricular region to the surface of the tectal neuropil (white dashed line) in both wild-type (n=6) and reln -/- (n=6) larvae at 5 dpf, suggesting that radial fibers are not contributing to layer-specific guidance of RGC axons by Reelin.