Fig. 2. MB mitotic clones induced in Drosophila early first instar larvae. In a heterozygous (lio²/+) genetic background, lio²/lio² MB clones display wild-type morphology (compare A with B), meaning that the defects observed in the lio²/lio² genetic background are non-cell-autonomous. In a lio²/drl^R343 genetic background (C), labeling of a single MB neuroblast lineage reveals that the mutant axons, once having crossed the midline, follow the contralateral ß lobe (arrow). The dashed line indicates the midline. The genotype is GAL-C155, hs-FLP, UAS-mCD8-GFP; tubP-GAL80 FRT40A/FRT40A in A, GAL-C155, hs-FLP, UAS-mCD8-GFP; tubP-GAL80 FRT40A/lio² FRT40A in B and GAL-C155, hs-FLP, UAS-mCD8-GFP; tubP-GAL80 drl^R343 FRT40A/lio² FRT40A in C. Scale bars: 50 µm.