Fig. 7. Eph is not required for branch formation but for guidance of axon branches within the dorsal lobes of the MB. Axonal projections of labeled /ß neurons generated by MARCM (Lee and Luo, 2001) labeled with UAS-mCD8:GFP. Images of one half of the MB, double-labeled with anti-GFP (green in A,C,E,G and shown alone in B,D,F,H) and anti-Fas2 (red in A,C,E,G) to visualize the projections of /ß neurons. (A,B) In wild type, a single-labeled /ß neuron bifurcates, sending one projection dorsally in the lobe and one medially in the ß lobe. Inset in A shows the axon projection (arrowhead) within the peduncle of this singly marked clone. (C,D) In Eph^x652 mutant MBs where the dorsal lobe is absent, a single-labeled /ß neuron bifurcates as in wild type, but both projections extend along the medial projecting ß lobe (arrows in D). Unlike wild type, extra branches can be seen along the length of both branches in the mutant (arrowheads in D). Inset in C shows the axon projection (arrowhead) within the peduncle of this singly marked clone. (E,F) In Eph^x652 mutant MBs where the dorsal lobe is present, but reduced multiple labeled /ß neurons show fewer axons within the lobe compared with the medial ß lobe. (G,H) A single-labeled /ß neuron in an Eph^x652mutant where the overall morphology of the MB is unaffected, showing normal bifurcation and branching. Genotypes: (A,B) elav-Gal4, UAS-mCD8GFP, hs-FLIP (X)/+ or Y;FRT^G13/FRT^G13 Gal80;Eph^x652/CiD; (C-H) elav-Gal4, UAS-mCD8GFP, hs-FLIP (X)/+ or Y;FRT^G13/FRT^G13 Gal80;Eph^x652/Eph^x652.