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. Author manuscript; available in PMC: 2015 Apr 10.
Published in final edited form as: Cell Rep. 2014 Mar 27;7(1):153–165. doi: 10.1016/j.celrep.2014.02.037

Figure 7. Robo3 acts downstream of Hb9 to direct the lateral position of MP1 axons.

Figure 7

A, Top: Fluorescent in situ for robo3 mRNA (green) in Stage 16 embryos. Anterior is up. MP1 neurons are labeled by C544-Gal4 in magenta and circled in the single-channel images. Many MP1 neurons do not express robo3 in hb9 mutants (empty arrowhead). A, Bottom: MP1 axons project along the intermediate FasII bundle in hb9 heterozygotes (arrow), but are often shifted to the medial pathway in hb9 mutants (arrow with an asterisk). B: MP1 neurons were scored as robo3+ or robo3− and as projecting along the medial or intermediate (Int.) FasII tract. A significant correlation was detected between robo3 expression and lateral position in both hb9 +/− and hb9−/− embryos (Fisher’s exact test, p<0.001). C: Over-expressing robo3 rescues the medial shift phenotype of MP1 axons in hb9 mutants (p<0.001, Fisher’s Exact Test). Arrows point to MP1 axons in the correct position; arrows with asterisks point to medially shifted axons. All mutants were scored blind to genotype. Scale bars represent 10 μm. Hb9 +/+ denotes C544-Gal4/+; UAS-TauMycGFP/+. Hb9 +/− denotes C544-Gal4/+; hb9ad121, UAS-TauMycGFP/TM3. Hb9 −/− denotes C544-Gal4/+; hb9ad121, UAS-TauMycGFP/hb9kk30. Hb9 −/− HARobo3 G.O.F. denotes C544-Gal4/UAS-HARobo3.T15; hb9ad121, UAS-TauMycGFP/hb9kk30. See also Figure S5.