Figure 5.

Hairy represses terminal patterning genes. Nuclear cleavage cycle-14 embryos were hybridized with the indicated digoxigenin-labeled antisense RNA probes. The wild-type staining patterns (“control”) are shown in A–D. fkh, hkb, and tll are expressed in both the anterior and posterior poles whereas ems is expressed in a single stripe near the head. (E–H) Expression of the terminal patterning genes in a transgenic embryo that expresses the wild-type form of hairy. The anterior, but not posterior, patterns of fkh, hkb, and tll are repressed. In addition, there is an anterior shift in the ems pattern (compare H with D). (I–L) Same as E–H except that the transgenic embryos express a mutant form of hairy that lacks the PLSLV motif. Efficient repression of fkh, hkb, and tll is observed. (M–P) Same as I–L except that the embryos express a mutant form of hairy that lacks the WRPW motif and contains an optimal dCtBP interaction sequence (PLSLV was changed to PLDLS). There may be a slight attenuation in the anterior staining of fkh and hkb, but otherwise the expression patterns appear normal (see A–C). In addition, there is no anterior shift in the ems pattern. Although this hairy product is essentially inactive in these assays, it is able to mediate substantial repression of Sxl (see Fig. 4E).