Figure 1 | Phenotypes of loss- and gain-of-function of head organizer TFs in frogs. (a) Expression patterns of otx2, otx5, lim1 and gsc in Xenopus gastrula embryos. Schematic representation shows co-expression of lim1, otx2, otx5 and gsc in the head organizer 49,16,22,23,56 and lim1 expression in the trunk organizers16,56. A double-headed arrow indicates the dorsal (D) and ventral (V) axis. Co-expression of these genes in X. tropicalis early gastrula embryos was shown with in situ hybridization using hemisections. In anterior neuroectoderm, otx2 is weakly expressed, while otx5 is more strongly expressed. Arrowhead, dorsal blastopore; open arrowhead, expression in the anterior neuroectoderm; and dashed line, boundary of ectoderm and mesoderm. (b) Loss- of-function analysis in X. tropicalis. Phenotypes of normal embryos (control morphants) and head-reduced embryos (lim1/otx2/otx5/gsc morphants) are shown. Sagittal section and whole mount in situ hybridization of the telencephalon marker (eomes) and the midbrainhindbrain boundary marker (en2) showed that forebrain, midbrain and foregut were shrunk in head-reduced embryos. Note that the notochord reached the anterior-most region in the morphant. Tailbud embryos are shown in lateral (anterior to the left; three left panels) or dorsoanterior (right-most panels) views. fb, forebrain; fg, foregut; no, notochord. (c) Gain-of-function analysis in X. laevis. Left panels show lateral views of a secondary head with one eye generated after ventral injection (inj.) of a cocktail of mRNAs as indicated. Right panels show immunostaining of head organizer cocktail-injected embryos against notochord by MZ15 (dorsal view of the same embryo as shown in the left panel) and somites by 12/101 (lateral view), respectively. Scale bar, 250 mm.
Image published in: Yasuoka Y et al. (2014)
Copyright © 2014. Image reproduced with permission of the Publisher, Macmillan Publishers Ltd.
| Gene | Synonyms | Species | Stage(s) | Tissue |
|---|---|---|---|---|
| lhx1.L | lim-1, Lim1, lim1, Xlim-1, Xlim1 | X. laevis | Throughout NF stage 10.5 | dorsal marginal zone upper blastopore lip dorsal involuting marginal zone |
| otx2.L | otx-2, otx2-a, otx2-b, otxA, Xotx-2, Xotx2 | X. laevis | Throughout NF stage 10.5 | dorsal marginal zone upper blastopore lip dorsal involuting marginal zone |
| crx.L | crx-a, crx-b, otx5, otx5b, Xotx5, Xotx5b | X. laevis | Throughout NF stage 12 | involuted dorsal mesoderm presumptive axial mesoderm |
| gsc.L | goosecoid, gsc-a, gsc-b, Xgsc | X. laevis | Throughout NF stage 12 | involuted dorsal mesoderm presumptive axial mesoderm |
| en2.L | En-2, en2-a, en2-b, eng2, engrailed 2, engrailed homolog 2, engrailed-2, maben, xen2 | X. laevis | Sometime during NF stage 31 to NF stage 32 | midbrain-hindbrain boundary |
| eomes.L | eomesodermin, tbr2, xeomes | X. laevis | Sometime during NF stage 31 to NF stage 32 | forebrain |
Image source: Published
| Experiment + Assay | Source | Phenotypes and Disease | ||
|---|---|---|---|---|
| Xtr Wt + otx2 MO + crx MO + gsc MO + lhx1 MO + NF31-32 (whole-mount microscopy) | Fig. 1 b row2 |
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| Xla Wt + otx2 + ssbp3 + ldb1 + lhx1 + NF37/38-39 (whole-mount microscopy) | Fig. 1. C |
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| Xla Wt + tle1 + gsc + otx2 + ssbp3 + ldb1 + lhx1 mRNA + NF37/38-39 (whole-mount microscopy) | Fig. 1. C |
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