Fig. 4. Snail represses sog expression. Wild-type (A-D) and Tollrm9/Tollrm10 mutant (E-H) embryos were stained with either a snail (A,B,E,F) or sog (C,D,G,H) hybridization probe. The embryos in A-D and F,H contain a stripe2-snail transgene. (A,B) Lateral and ventral views of wild-type embryos that contain a stripe2-snail transgene. An ectopic stripe of snail expression is detected in addition to the normal pattern in the ventral mesoderm. (C,D) Lateral and ventral views of wild-type embryos expressing the stripe2-snail transgene. There are gaps in the sog expression pattern within the lateral, neurogenic ectoderm near the position of the Snail stripe. (E,F) Tollrm9/Tollrm10 mutant embryos that lack (E) or contain (F) a stripe2-snail transgene. Mutant embryos that lack the transgene exhibit residual snail staining at the poles (E). The stripe2-snail transgene provides the sole source of snail expression in middle body regions (F). This stripe is transiently expressed and rapidly disappears in older embryos (data not shown). (G,H) sog staining patterns in Tollrm9/Tollrm10 mutant embryos that either lack (G) or express (H) a stripe2-snail transgene. In mutant embryos lacking the transgene, sog is uniformly expressed along the anteroposterior axis, with the exception of the extreme termini (G). The stripe2-snail transgene creates a gap in the sog pattern (H).
