Fig. 3. Proneural genes regulate medulla differentiation. (A) L(1)sc (green) and Ase (magenta) are expressed in NE cells and NBs, respectively. (B) Schematic of lateral view of the optic lobe. Lamina neurons (yellow), L(1)sc-expressing cells (green), NE cells (blue) and NBs (magenta) are shown. (C) Expression pattern of proneural genes in square of B. Among the proteins of the AS-C, Sc is expressed in both NE cells and NBs, L(1)sc in the medial edge of NE cells, and Ase in NBs, respectively. (D,D') Initiation of NB differentiation was delayed in da¹⁰ clones. Dpn expression (magenta) almost disappeared in the da¹⁰ clones, shown by the absence of GFP (blue in D) and of white in D'. (D') Higher magnification of square in D. (E,E') Expression of L(1)sc (green) was not affected in da¹⁰ clones, shown by the absence of GFP (blue), while onset of Dpn expression was delayed (magenta). (E') Higher magnification of square in E. Clones are indicated by the absence of white signal. L(1)sc was shown in green and Dpn in magenta. (F) Genomic locus of AS-C and deficiency lines used. Deleted genes are depicted by crosses. (G) Onset of Dpn expression (magenta) was delayed in Df(1)260-1 clones, indicated by the absence of white signal. (H) Onset of Dpn expression (magenta) was not affected in Df(1)sc10-1 clones, indicated by the absence of white signal. (I) Onset of Dpn expression (magenta) was slightly delayed in Df(1)sc19-1 clones shown by the absence of white signal. Expression of L(1)sc is shown by green. Broken yellow line shows the border between NE and NBs, and yellow arrowheads indicate cells not expressing Dpn in the clones. (J) Onset of Dpn expression (magenta) was not affected in Df(1)ase1 clones shown by the absence of white signal. (K) Summary of the phenotypes. Onset of Dpn expression was delayed by 4-6 rows of cells in the clones of da¹⁰ or Df(1)260-1 (left), and delayed by one or two rows in the clones of Df(1)sc19 (right). Clones are within the black lines. NBs (magenta), L(1)sc-expressing cells (green), NE cells (blue) and cells yet to express Dpn (gray) are shown. L(1)sc expression remained in da¹⁰ clones but not in Df(1)260-1 clones (half gray and half green circles).