A method to visualize different bouton types at the Drosophila larval NMJ

<p>Shown are the neuromuscular junctions (NMJs) at muscle 6/7 in abdominal segment 2 in a third instar <em>Drosophila</em> larva. Panel A shows an NMJ from an animal expressing membrane bound Green Fluorescent Protein (mcd8::GFP) from the <em>futsch</em>[C380]-GAL4 (C380-GAL4 or BG380-GAL4) driver that expresses in all motor neurons (Sanyal, 2009; Budnik et. al., 1996). Accordingly, the two motor axons that innervate this muscle (MN6/7-Ib and MNSNb/d-Is; Hoang and Chiba, 2001) contain GFP label and all boutons on muscle 6/7 are labeled with GFP fluorescence (green in panel A, anti-synaptotagmin staining is used for independent visualization of these synaptic boutons, in red). In panel B, GFP is expressed from the same <em>futsch</em>[C380]-GAL4 but along with GAL80 expressed from the ChAT promoter (Cha-GAL80; Kitamoto, 2002). This leads to an appreciably weaker expression of GFP in type Ib boutons, and by extension, MN6/7-Ib. As a result, following anti-synaptotagmin staining, type Ib and Is boutons (and, therefore, contributions to this synapse from MN6/7-Ib and MNSNb/d-Is) can be discriminated quite easily. Note that only the type Is boutons are double labeled with GFP and synaptotagmin (double arrows), whereas the type Ib boutons are only seen from synaptotagmin staining (double arrowheads). This reagent might be a useful tool to easily discriminate between these two bouton types at a widely studied model synapse.</p> <p>References:</p> <p>1. Budnik V, Koh YH, Guan B, Hartmann B, Hough C, Woods D, Gorczyca M. Regulation</p> <p>of synapse structure and function by the <em>Drosophila</em> tumor suppressor gene dlg. Neuron. 1996 Oct;17(4):627-40.</p> <p>2. Sanyal S. Genomic mapping and expression patterns of C380, OK6 and D42 enhancer trap lines in the larval nervous system of <em>Drosophila</em>. Gene Expr Patterns. 2009 Jun;9(5):371-80.</p> <p>3. Hoang B, Chiba A. Single-cell analysis of <em>Drosophila</em> larval neuromuscular synapses. Dev Biol. 2001 Jan 1;229(1):55-70.</p> <p>4. Kitamoto T. Conditional disruption of synaptic transmission induces male-male</p> <p>courtship behavior in <em>Drosophila</em>. Proc Natl Acad Sci U S A. 2002 Oct 1;99(20):13232-7.