Fig. 4. Differential repression of minimal eve stripe enhancers by Knirps1-429 and 1-330, demonstrates differential sensitivities to Knirps activity. Repression of eve stripe 2/3-lacZ reporter gene demonstrates differential sensitivities of eve stripe 2 versus stripe 3 enhancers to Knirps expression. Patterns of lacZ expression in embryos prior to heat shock (A,D) and after heat shock (B,C,E,F). After a 10-minute heat shock, the majority of embryos expressing Knirps 1-429 showed repression of eve stripe 3 (B). After a 30-minute heat shock, the majority of embryos showed repression of both stripe 2 and 3 (C). A significant percentage of embryos showed only partial repression of stripe 3 upon overexpression of Knirps 1-330 (E). The majority of embryos demonstrated a loss of stripe 3, but not stripe 2 after 30 minutes of heat shock (F). (G,J) Unperturbed reporter gene expression. Effects of overexpression of Knirps1-429 and 1-330 in embryos carrying the eve stripe 3/7 lacZ reporter (G-I) or eve stripe 4/6 lacZ reporter (J-L). Full-length Knirps was a more potent repressor, but Knirps 1-330 was capable of repressing the minimal eve stripe 4/6 element (see text for details). The patterns shown in H and K are representative of embryos heat shocked for 15 minutes, whereas the patterns shown in I and L are typical of embryos heat shocked for 30 minutes. Embryos are oriented with anterior towards the left, dorsal side upwards.