Figure 4. A binary, Notch-mediated cell fate decision specifies T4 vs. T5 neurons.

(A) Ato⁺/Pros⁺ GMCs (arrowheads; blue and green) were distributed in a salt-and-pepper manner in the dIPC.

(B) T4/T5 neurons marked by Acj6 (cyan) expressed the Notch sensor Hey (arrow; red) in a salt-and-pepper manner.

(C,D) T4 and T5 neurons of the same subtype are sibling neurons and projected to the same retinotopic position in their target neuropiles (Brp, white). Twin-spot MARCM clone visualized with T4/T5-Gal4 of sibling T4 and T5 neurons of the horizontal (subtype b) [arrow in (C)], and vertical system (subtype d) [arrow in (D)]. See also Figure S2.

(E,F) Notch mutant MARCM clones visualized with T4/T5-Gal4 of a dividing GMC produced two sibling T4 neurons of the same subtypes (arrow) for both the horizontal (E) and vertical systems (F). The two T4 neurons projected to the same retinotopic position. See also Figure S2.

(G) Ato⁺ NBs (yellow) produce GMCs that divide once to produce sibling T4 (Notch^OFF) and T5 (Notch^ON) neurons of the same subtype.