Fig. 5. Pdm closes the second temporal identity window in the NB3-1 lineage. (A,B) Neuroblast expression of Kr and Cas in pdm mutant and pdm misexpression embryos. One hemisegment is shown. Kr or Cas, brown; the positional marker Engrailed, blue. NB3-1 is outlined. (A) In pdm mutants, Kr expression persists through late stage 11 (it is normally switched off by mid stage 11; see Fig. 1A) and Cas expression is delayed until mid stage 12. (B) In pdm misexpression embryos (insc-gal4 UAS-pdm2), Kr expression is lost prematurely and Cas is expressed precociously (compare with Fig. 1A). (C,D) RP neuron specification in pdm mutant and pdm misexpression embryos. One hemisegment of a stage-16 CNS is shown as a maximum intensity projection. Midline, left; anterior, up. A phenotype summary is shown to the right. (C) In pdm mutant embryos there are two to three ectopic RP3 neurons; RP1, RP4 and RP5 neurons are usually normal (Table 1). (D) pdm misexpression (insc-gal4 UAS-pdm2) results in the frequent loss of the RP5 neuron (both rows) and in the occasional loss of the RP3 neuron (second row); RP1/RP4 are normal (Table 1). Scale bars: 10 µm in A,B; 3 µm in C,D.