Fig. 4. Dorsoventral patterning defects in csn5^p mutant embryos. Embryos were hybridized with digoxigenin-labeled antisense RNA probes and are oriented with dorsal upwards and anterior towards the left (A,B,G,H) except C-F, which are dorsal views. Csn5p mutant embryos were derived from csn5p germline clones. (A,B) Wild-type (wt) and mutant (csn5^p) embryos undergoing cellularization after hybridization with a snail probe. In the mutant embryo, the snail expression domain forms on the ventral side as in wild type, but has a wavy border. (C,D) Cellularizing wild-type and mutant embryos after hybridization with a rhomboid probe. rhomboid is expressed in two lateral stripes in the presumptive neuroectoderm. In the mutant embryo, the two lateral stripes are wavy. (E,F) Wild-type and mutant embryo at the onset of gastrulation hybridized with the rhomboid probe. In addition to the two lateral stripes, rhomboid is expressed in the dorsal ectoderm in response to the dpp signaling molecule at this stage. In the csn5^p mutant embryo, the dorsal ectoderm staining is expanded, suggesting that CSN5 normally restricts dpp signaling. (G,H) Cellularizing wild-type and mutant embryos hybridized with a tolloid probe. tolloid expression is normally excluded from the ventral side of the embryo by the Dorsal protein. In the mutant embryo, the pattern is severely distorted, with tolloid expression observed in parts of both the ventral and dorsal half of the embryo.