FIG. 6.

Knirps N-terminal repression activity functions in dCtBP mutant embryos. (A) eve stripe 2 lacZ reporter in a wild-type embryo. (B) eve stripe 2 lacZ reporter in a mutant embryo lacking maternal dCtBP. Anterior and posterior boundaries of the stripe are less well defined. (C) Repression by Gal4-Knirps 75-332 in a dCtBP mutant. Ventral expression of the transgene is repressed. (D) Repression by Gal4-Knirps 75-364mut, lacking the dCtBP binding motif. (E) Repression by Gal4-Knirps 75-429mut, lacking the dCtBP binding motif. Embryos are oriented with anterior being to the left and dorsal being to the top. Lateral views are shown, except for the ventrolateral view in panels C and E. CtBP embryos were generally shorter and broader than wild-type embryos. In the absence of repressor, 4% of embryos showed loss of ventral expression of the eve stripe 2 lacZ stripe in the mutant embryos (versus less than 1% in wild-type embryos [Table 1]). For the repressor shown in panel C, 31% of embryos showed loss of ventral staining (n = 140); for panels D and E, 31% (n = 39) and 75% (n = 65) of embryos, respectively, showed loss of ventral staining.