Fig. 3. Notch-regulated gene expression in pm8. (A) DIC image of wild-type embryo at the 1.5-fold stage focused at the plane of the pharyngeal primordium (bracket); anterior is left. (B) Same embryo as in A, showing GFP expression from enh^A::GFP (pKG55). The bent line indicates a pair of sister cells in the pharynx that express ref-1 independent of Notch signaling; these cells are below the focal plane shown, and appear faint. Asterisks here and in panels D and E indicate intestinal cells with faint GFP expression persisting from the second endodermal Notch interaction. (C,D) DIC and fluorescence image of 1.5-fold stage embryo showing C. briggsae enh^A::GFP expression. (E) GFP expression after mutating the potential NK site in enh^A to CTGTGCTGC. (F) GFP expression after mutating all WGATAR sequences in enh^A to WCATAR. (G,H) DIC and fluorescence images of a 3-fold stage embryo showing enh^A::GFP expression in pm8. Small spots appearing posterior to the pharynx in H and below in J are autofluorescent granules in the intestine not related to transgene expression. (I) Lack of GFP expression in pm8 after mutating the NK site to CTCAAGTTC. (J) Expression of the same transgene used for I after heat-shock expression of ELT-2/GATA.