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Figure 2. Whole mount in situ hybridization assays of embryos injected with FoxD4L1/D5 mRNA. A: Examples of FoxD4L1/D5 causing an increase in downstream gene expression. In neural plate stage embryos, the expression domains of FoxB1 and XSpr2 are broader on the FoxD4L1/D5-injected side (right; indicated by βGal-expressing (red) cells). Lines indicate width of neural plate on injected (right) and control (left) sides of embryos. Dorsal views with anterior to the bottom. The FoxB1 expression domain also extends more anterior (bracket) compared to anterior limit on control side (arrow). At gastrula stages, the endogenous domains of Fgf8b and Oct-1 surround the yolk plug; the anterior extent of the domain is indicated by an arrow on the control side. The cells expressing FoxD4L1/D5 (red nuclei) in the neural plate (bracket) also express increased levels of Fgf8b and Oct-1. Dorsal views with anterior to the bottom. Inset in Oct-1 embryo: higher magnification showing FoxD4L1/D5-cells with red nuclei and blue cytoplasm. At gastrula stages, VegT/Brat and BJ051739 are ectopically induced in the animal cap ectoderm. Animal pole views. B: Examples of FoxD4L1/D5 causing a decrease in downstream gene expression. In neural plate stage embryos, MGC52564, MGC52940, Neptune, Dlx6, and Blimp1 are expressed in the border zone that separates the anterior neural plate (np) from the epidermis (epi). For each gene, this region shows decreased expression at the site of FoxD4L1/D5-expressing cells (red nuclei, arrows). MGC52564, MGC52940, Dlx6, Blimp1 are anterior views with dorsal to the top; control side is on the left. Neptune is a side view with anterior to top and dorsal to right. In a gastrula embryo, the normal high level of FoxI1 expression in the animal cap ectoderm (epi) is greatly reduced in the FoxD4L1/D5-expressing clone (*), which is outlined for clarity. |
