Fig. 3.

mdlc mutants fail to maintain Pros and Elav in postmitotic neurons. (A) Genomic context of mdlc (CG4973), which resides in the intron of CG4390 on the opposite strand. The piggyBac transposon c04701 is inserted in the 5′ UTR of mdlc. (B) Wt MARCM clone showing Pros⁺ neurons lacking expression of Dpn and Ase. (C-E) mdlc mutant MARCM clones chosen to indicate the progression of neuronal phenotypes shown in J. (C) Middle-aged neurons (lying midway between the neuroblast and the oldest, most distal neurons) lack Pros expression (yellow arrowheads) but have not upregulated Dpn or Ase. (D) Middle-aged neurons lack Pros expression (yellow arrowheads) and Ase is derepressed in one of them (white arrow). (E) Middle-aged neurons lack Pros expression (arrow and arrowheads); Ase is derepressed in several of these cells (e.g. arrow), and two Ase⁺ cells have also derepressed Dpn (arrowheads). (F,G) mdlc mutant neurons lose Elav. (F) Wt neurons in which Pros and Elav are present but Ase is absent. (G) mdlc mutant MARCM clone showing the loss of both Pros and Elav from a small number of neurons (arrow and arrowhead); Ase is derepressed in one of these cells (white arrow). (H) Quantification of neuronal phenotypes in mdlc^- clones (n=54 clones). Numbers are given as the percentage of the total number of cells in the clone. *P<0.05, **P<0.01; error bars indicate s.d. (I) Comprehensive quantification of absolute numbers of non-wt neuronal phenotypes in mdlc mutant clones, showing the overlap of Pros^-, Ase⁺ and Dpn⁺ neurons (n=54 clones). This analysis demonstrates that the majority of Dpn⁺ cells comprise a subset of Ase⁺ neurons [81 of 94 Dpn⁺ neurons (86%) are also Ase⁺], and that the Ase⁺ cells are a subset of Pros^- neurons [164 of 174 Ase⁺ neurons (94%) are Pros^-]. (J) Model illustrating the progression of mdlc mutant clone phenotypes. Scale bar: 10 μm.