Distribution pattern of WGA:GFP in the Drosophila larval brain upon expression in the Bolwig's Organ

To express WGA:GFP robustly using the Gal4/UAS system, a Drosophila codon-optimized wheat germ agglutinin (WGA) was subcloned into the JFRC14-CS-dGFP construct. This UAS-dWGA:GFP transgene was then integrated into a specific landing site, containing the 3xP3-RFP marker, in the 3rd chromosome. Flies containing the UAS-dWGA:GFP transgene were then crossed to a visual system targeting longGMR-Gal4 strain. (A) Progeny larvae from this cross displayed a punctate GFP-label in the Bolwig's Organ (larval visual system). (B) The GFP-label was quite widely distributed in the brain hemisphere outside of the Bolwig's Organ terminals (indicated by arrow). Arrowheads indicate GFP-label in unidentified cells. These observations support a previous report that WGA can be transferred trans-synaptically in Drosophila (Tabuchi et al. 2000). Squiggle-arrow indicates a likely non-specific uptake area. The developing adult visual system zone is indicated by an asterisk. Note, the 3xP3-RFP expression labels the visual system and numerous cells in the brain.