Fig. 7

Fig. 7 Rescue of the boz ventralized phenotype by expression of bozozok RNA. (a– c) Injection of wild-type nieuwkoid/dharma RNA in early blastomeres of either wild-type or boz mutant embryos led to a hyperdorsalized phenotype. Embryos are at 12-hpf stage. Embryos are oriented anterior to the top. (a) Uninjected wild-type postgastrula embryo stained simultaneously for the notochord and floorplate marker shh and the hindbrain marker krox20. At this stage, shh expression is detected along the entire anteroposterior axis in the cells of the floorplate and notochord. krox20 expression is detected only in the hindbrain region and is restricted to rhombomeres 3 and 5. (b) Injection of wild-type nieuwkoid/dharma RNA in distant blastomeres of eight-cell-stage stage wild-type or boz heterozygote embryos led to the formation of expanded or ectopic dorsal fates as indicated by the ectopic expression of shh and radially expanded krox20 expression. (c) Injection of nieuwkoid/dharma RNA in boz homozygotes as in (b) led to the formation of ectopic dorsal fates. (d–f) Analysis of wild-type and boz mutant embryos following injection of nieuwkoid/dharma RNA directly into the YSL. Wild-type (d) and bozozok mutant (e and f) embryos at 22-hpf stage following injection of nieuwkoid/dharma RNA into the YSL and staining for the expression of α-coll2a. Embryos are in profile and oriented anterior to the top. YSL injection of nieuwkoid/dharma RNA can rescue the formation of dorsal midline tissues in boz homozygotes (e) but does not lead to the formation of hyperdorsalized postgastrula phenotype in either boz mutants (e) or their wild-type (d) and heterozygote siblings. (f) Fluorescence image of rescued boz mutant embryo in (e) revealing the distribution of lineage tracer that was coinjected with the nieuwkoid/dharma RNA. No labeled cells were detected in the midline tissues. However, frequently a small group of labeled cells was detected in the posterior region of the tail (white arrowhead).