Fig. 4. Loss of DBDG in Notch mutants. (A,B) Double labeling of repo mRNA (purple) and nubbin mRNA (orange) in stage 12 embryos. (A) Two nubbin-positive cells (dotted circle; one is the dbd neuron and the other is the dda neuron) are associated with a glial cell (arrow) in normal embryos. (B) In Notch^55e11 mutant embryos, increased numbers of nubbin-positive neurons (encircled by dotted line) are present, but no DBDG is generated. The Notch mutant shows a neurogenic phenotype, resulting in an excess of repo-positive cells such as PG3 glial cell (asterisk) and ligament cells (bracket) in the PNS. gcm mRNA expression in a normal embryo (C) and a Notch^55e11 mutant (D) at the same stage shown in A and B. gcm expression in the dbd lineage (C, arrows) is absent in the Notch embryo (D, arrow). Insets in C and D are higher magnification views of one parasegment. Dorsal is up and anterior to left.