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Fig. 8. XRDH10 contributes to CNS patterning and the posteriorizing effect of retinol. Morpholino oligonucleotides (MOs; each 2.6 pmol per embryo) were injected into the margin of one blastomere at the two-cell stage. The non-targeted mRNA constructs XRDH10* and mRALDH2 (each 1 ng) and the lineage tracer nlacZ mRNA were co-injected. Embryos are shown in dorsal view (anterior to the top). (A-F) Late gastrula embryos. XRDH10-MO, XRALDH2-MO, or a combination of both morpholinos, cause a reduction and posteriorward retraction of HoxD1expression, which is reverted by XRDH10* and mRALDH2 mRNA. (G-L) Neurula embryos showing expression of En2 (midbrain-hindbrain boundary), HoxB3 (hindbrain rhombomeres 5 and 6) and HoxC6 (anterior spinal cord). (M-R) Tailbud embryos depicting expression of Rx2A (eyes) and Krox20 (rhombomeres 3 and 5). (S) Effects of XRDH10 and XRALDH2 knockdown on hindbrain patterning. The posteriorward shift of Krox20 expression is shown in response to MO injections at the indicated doses. (T-W) Treatment with 100 µM retinol at stages 9-12 induces a robust anterior expansion of HoxD1 expression in late gastrula embryos (V). XRDH10-MO reverts the effect of retinol on the injected right-hand side (W). Frequency of embryos with the indicated phenotype was: A, 77/88; B, 55/105; C, 30/68; D, 54/88; E, 19/21; F, 23/25; G, 34/35; H, 17/31 (En2); H, 30/31 (HoxB3); H, 27/31 (HoxC6); I, 15/33 (En2); I, 31/33 (HoxB3); I, 32/33 (HoxC6); J, 6/9 (En2); J, 8/9 (HoxB3); J, 5/9 (HoxC6); K, 20/23; L, 39/39; M, 10/10; N, 35/73; O, 37/69; P, 38/60; Q, 10/10; R, 13/14; T, 9/9; U, 7/13; V, 9/9; W, 20/33 embryos. |
