Fig. 2. Subcellular localization of Fmr1 in DA neurons in Drosophila larvae. (A) Schematic representation of all the neurons in the dorsal cluster of an abdominal hemisegment. des, dorsal external sensory neurons; dda, dorsal dendritic arborization neuron;. dbd, dorsal bipolar dendritic neuron. Only the dda and dbd neurons are labeled by GFP using Gal4 109(2)80. (B) Cytoplasmic localization of Fmr1-GFP fusion protein in a ddaF neuron is indicated by the arrow. The expression of Fmr1-GFP was driven by Gal4 109(2)80. Scale bar: 10 µm. (C) The Fmr1-GFP signal in dendrites (arrow) is relatively weak compared with that in the cell body. This image was enhanced using Photoshop to demonstrate the localization of Fmr1-GFP in dotted structures in dendrites of dorsal cluster DA neurons. (D) UAS-GFP driven by Gal4 109(2)80 in these DA neurons indicates the dendritic branching patterns. (E) GFP-labeled DA neurons in a wild-type third instar larva are indicated by arrows. (F) Antibody staining of the same DA neurons as in E demonstrates the cytoplasmic localization of endogenous Fmr1. The arrowhead indicates the proximal segments of dendrites. The arrow indicates a muscle fiber that was also labeled by Fmr1-specific monoclonal antibody. (G) UAS-GFP-labeled DA neurons in a Fmr1 mutant third instar larva are indicated by arrows. (H) Antibody staining of the same DA neurons in Panel G demonstrates the absence of Fmr1 positive signals in Fmr1 mutants.