The distribution pattern of WGA:GFP in the Drosophila larval brain upon its 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 (also called UAS-dWGA:GFP). This UAS-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 (marked by RFP). Arrowheads indicate GFP-label in unidentified cells. These observation 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.

为借助GAL4/UAS双元表达系统（Gal4/UAS system）高效稳定地表达WGA:GFP，我们将经果蝇密码子优化的麦胚凝集素（wheat germ agglutinin, WGA）亚克隆至JFRC14-CS-dGFP构建体（亦命名为UAS-dWGA:GFP）。随后将该UAS转基因元件整合至三号染色体上带有3xP3-RFP标记的特异性整合位点。将携带UAS-dWGA:GFP转基因元件的果蝇与靶向视觉系统的longGMR-Gal4品系进行杂交。(A) 该杂交得到的子代幼虫在玻尔维格器官（幼虫视觉系统）中呈现点状GFP标记信号。(B) GFP标记信号广泛分布于玻尔维格器官末梢（以RFP标记）外侧的大脑半球区域；箭头标注了未鉴定细胞中的GFP阳性信号。上述观测结果佐证了此前关于WGA可在果蝇体内跨突触传递的研究报道（Tabuchi等，2000）。波浪箭头指示一处疑似非特异性摄取区域；星号标注了发育中的成虫视觉系统区域。