Figure 7.

The −179 E-box is required for mls-1 activity. A genomic segment carrying the mls-1 locus with different mutations in the −179 E-box was assayed in transgenic lines for rescue of uterine/vulval muscle fate decisions in an mls-1(cc570) mutant background. Each data point represents the mean percent rescue for an independent transgene array. Error bars give standard error of the mean. Rescue activity was strong in all transgenic lines with wild-type (CAgaTG) and Twist consensus (CAtaTG) E-boxes; little or no rescue was observed with non-E-box sequences cc570 (tAgaTG) or ClaI (atgcat). A consensus MyoD E-box (CAgcTG) yielded rescue in one of three transgenic lines; activation in this line might potentially involve Twist, MyoD, or another HLH factor, and has not been further analyzed.