(A) Reverse MARCM analysis establishes a non-autonomous Dscam2 requirement in lamina neurons (see Figure S3). Representative 3D renderings of L4 neurons displaying wild-type (left panel) and +1 (right panel) dendritic patterning phenotypes. Quantification of these phenotypes, scored in the presence of unlabeled wild-type or unlabeled Dscam2 mutant lamina neurons, is shown in the table.
(B–D) DL-MARCM analyses reveals Dscam2 requirement in specific lamina neurons (see Figure S4). 3D renderings showing MARCM generated control (left panel) or Dscam2 mutant (right panel) lamina neurons (green) in contact with FLP-out labeled L4 neuron (red). Phenotypes of FLP-out L4s are quantified in tables. (B) FLP-out generated L4 neurons do not produce an ectopic branch when adjacent to a Dscam2 MARCM generated L4. (C,D) FLP-out L4s produce an ectopic +1 branch when targeting to a fascicle containing a MARCM generated Dscam2 L2 (C) or L1 (D). As previously described (Lah et al., 2014), we also observed L1 and L2 dendrites lacking Dscam2 occasionally project into adjacent cartridges (see example in C). In most cases, however, this ectopic branch is not correlated with a defect in L4 targeting (see Figure S5). Additional dendritic branches indicated (*). Scale bar, 5 μm.