Fig. 6

Expression of dorsal gene markers is unaffected by UV treatment in type-A embryos. Embryos were hybridized with a digoxigenin-labeled antisense RNA probe complementary to the Axial gene RNA (A-F) or stained with the anti-ntl (zebrafish Brachyury, ZF-T) antibody (G,H). (A,B) UV-retarded embryo at 30% epiboly and control embryo at 50% epiboly stage, respectively. Axial expression marks the region of the fish organizer. (C,D) UV embryo at 50 % epiboly and untreated control at 80% epiboly, respectively. Axial -postive cells have involuted and spread towards the animal pole along the dorsal midline of the embryos. (E,F) UV-retarded and control embryo, respectively. Control embryo is at the 4-somite stage. (G,H) 14- hour embryos stained with the anti-ntl antibody. Embryo in G was UV treated. (H) An untreated control embryo. The notochord is indicated by n. Embryos were UV treated at early cleavage stages (3.6 mJ/cm²). Blastoderm margins are indicated by dots. Orientation of embryos is anterior up.