Fig. 2. Compact regulatory element displays enhancer-like properties of distance and orientation independence. (A,D) The regulatory element shown in Fig. 1F was inserted in either orientation into a vector containing divergently transcribed white and transposase lacZ reporter genes. When situated at -265 bp, Dorsal/Twist (dl/twi) activators within the element drive expression of the white reporter gene. Repression by Giant (gt) is evident in anterior and posterior regions (arrows). (B,E) In the presence of Dorsal, Twist, and Gal4 activators, a composite pattern of gene regulation is seen as in Fig. 1F with inhibition of Dorsal/Twist and activation by Gal4. (C,F) A similar expression pattern is observed with the divergently transcribed transposase lacZ promoter, with repression by Giant of Dorsal/Twist and activation by Gal4. Embryos are oriented anterior to left; lateral views (A,D) and ventrolateral views (B,C,E,F) are shown.