Sequential expression of temporal transcription factors within neuroblasts in the Drosophila CNS.

(A) The relative position of neuroblasts (NBs) in Drosophila embryo. The picture is the ventral view of NBs and shows Cas expression in the NBs at developmental stage 12. The bracket indicates a single segment. Dashed line corresponds to the midline. Scale bar: . (B) The expression levels of Hb, Kr, Pdm, and Cas in a single NB (NB 2–4 lineage) are shown from the developmental stage 10 to 12: early stage 10 (st. 10), early stage 11 (e11), mid stage 11 (11), late stage 11 (l11), mid stage 12 (12), late stage 12 (l12). (C) Schematic representation of the change of the expression pattern in a single NB. (D) The expression profiles of WT, loss-of-function, and overexpression mutants of the genes observed in the experiments (for references, see Table 2). (E) Reconstructed genetic network for sequential expression in Drosophila NBs. Repression from hb to cas (dashed line) was suggested to exist [26], although there is no direct verification. When the Drosophila network is invoked in this article, this regulation is also included. (F) Matrix representation of the Drosophila network.