Figure 3.

STEs exhibit diverse enhancer-blocking activity in transgenic Drosophila. (A) Diagram of the pWNHZ-STE transgene vector containing divergently transcribed lacZ (blue arrow) and miniwhite (mw, red arrow) reporters flanking the NEE (yellow circle) and H1 (blue circle) enhancers (see Methods). Red vertical oval: STEs or spacer control inserted between NEE and H1. (B–J) Representative images of transgenic embryos after whole mount in situ hybridized with the anti-lacZ (B–F), or the anti-white (G–I) RNA probes. DNA elements in these embryos are labeled at bottom right of each photo and probes used on bottom left. Embryos are shown in sagittal views with anterior to the left and dorsal up. (J) Quantitation of NEE-blocking in the whole neuroectoderm in transgenic embryos stained with the anti-lacZ probe (see Methods for details).