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Fig. 4. Alterations in cell lineages that border the neural plate in embryos with localized expression of VP16-Dlx3hd or EnR-Dlx3hd. Embryos were injected unilaterally with EnR-Dlx3hd or VP16-Dlx3hd at the 8-16 cell stage, cultured until the appropriate developmental stage and then examined by in situ hybridization (blue stain). β-galactosidase stain (magenta) indicates progeny of injected blastomeres. All embryos are shown as dorsal views with anterior to the top except for J and K which are lateral views, anterior to the right, and V-Y, anterior views, dorsal to the top. (A-F) Stage 13 embryos showing that markers of cells at the border of the neural plate (Xhairy2A and Xmsx-1) are ablated by VP16-Dlx3hd and shifted laterally by EnR-Dlx3hd. Arrows mark displacement caused by EnR-Dlx3hd relative to uninjected side of the embryo. (G-P) Stage 13 embryos showing identical effects on markers of neural crest precursors (Xsnail and Xslug). Lateral views of Xsnail expression illustrate the extent of the shift (J,K) seen in dorsal view (I, arrows). Transverse sections (O,P) showing Xslug expression (blue) and β-galactosidase (magenta) illustrate that the size of the Xslug expression domain is unaltered but occurs at the lateral margin of the cells expressing the injected mRNA. (Q-U) Primary neurons (marked by N-tubulin) are also ablated by VP16-Dlx3hd and displaced laterally by EnR-Dlx3hd in stage 14 Xenopus (Q-S) and 2-somite stage zebrafish (T,U). (V-Y) Stage 18 embryos showing cranial placode precursors (marked by Xsix1) shifted medially or laterally by localized expression of VP16-Dlx3hd and EnR-Dlx3hd, respectively (W,X). Note that the anterior domain of Xsix1 is unaffected, even where widespread expression of EnR-Dlx3hd ablates Xsix1 more laterally (Y). |
