... (not shown) and tup ( Fig. 4C ) expression in the presumptive serosa of A. gambiae embryos raises the possibility that zen activates the expression of one or more repressors in the serosa. It is unlikely that Zen itself is such a repressor since the expression of the A. gambiae zen gene in transgenic...

... be activated in cells containing intermediate levels of Dpp. We show that C15 expression requires both dpp and zen , thus forming a genetic feed-forward loop. The C15 regulatory element contains clusters of Smad- and Zen-binding sites in close proximity. Mutational analysis shows that the number of intact Smad...

... levels of Smads in the presumptive amnioserosa set the expression domain of zen , and then Smads act in combination with Zen to directly activate Race . This situation resembles a feed-forward mechanism of transcriptional regulation. In addition, we demonstrate that ectopically expressed Zen can activate...