| |
Figure 1. xNorrin induces anterior CNS formation in ventralized embryos.
(A-D) xNorrin mRNA induces anterior neural tissues, while Wnt11 mRNA restores only a partial dorsal axis (without anterior structures) in UV-irradiated embryos. (A) A wild-type embryo (stage 33); (B) an embryo UV-irradiated (50 uJ) at the vegetal pole; (C) a UV-irradiated embryo injected with Wnt11 mRNA (500 pg) into one cell at the four-cell stage (arrowhead: partial dorsal axis); (D) a UV-irradiated embryo injected with xNorrin mRNA (500 pg) as in (C) (arrow: head). (E) Summary of (A�D). Fraction of the population within each group is indicated. (F) Histological analysis of stage 40 embryos. Arrowhead: muscle; arrows: brain and eye. (G�J) Whole-mount in situ hybridizations to Sox3. (G) A wild-type (WT) embryo (100%, n = 65); (H) a UV-treated embryo (4% Sox3 positive, n = 70); (I) a UV+Wnt11 (500 pg) rescued embryo (45% Sox3 positive, n = 77); (J) a UV+xNorrin (500 pg) rescued embryo (83% Sox3 positive, n = 69). All embryos are shown with the anterior pole to the left. Arrowhead: posterior neural structure; arrow: anterior neural structure. (K) Neural marker expression detected by RT-PCR. xNorrin induced expression of anterior neural and pan-neural markers (En2, otx2, Xpax6, NCAM, and Sox2) in UV-irradiated embryos. Wnt11 induced only the hindbrain marker Krox20 in UV-irradiated embryos. |
