Figure 5.

NB7-1 has a single competence window for responding to Krüppel, Pdm, and Castor. (A) Schematic of wild-type and experimental temporal identity factor profile within the entire neuroblast layer of wild-type and experimental embryos. (B) One hemisegment of a stage 17 embryo is shown stained for the indicated markers; a summary of U neuron phenotype is shown in the box to the right. Anterior up, midline to left. The number of ectopic U3 neurons produced during the extended Kr expression is listed on the left. (C) Quantitation of U4/U5 neurons depending on the number of ectopic U3 neurons in the hemisegment. (D) Interpretation of results. Extended Kr expression results in a delay in Pdm and Cas expression; Kr, Pdm, or Cas expressed during the competence window can induce U3–U5 fates, but not after the end of the competence window (black line).