Transcriptional regulation of the unpaired3 gene during Drosophila development. Yu-Chen Tsai, Hsin-Yi Huang. Dept Life Science, Tung-hai Univ, Taichung, Taiwan.

   Unpaired3 (Upd3) regulates Janus Kinase/ Signal Transducers and Activators of Transcription (Jak/STAT) signaling during Drosophila eye development, gonad development, lymph development and in immune responses. It has been shown that upd3 is expressed in lymph gland to maintain cell fate of prohemocytes. upd3 is induced after septic injury and oral infection in midgut to maintain homeostasis of intestine in the larval stage. From our observation, we found the upd3 null mutant has small eye. upd3 is expressed in eye-antenna disc in the larval stages. In this study, we focus on the transcriptional regulation of the upd3 gene and further analyze the upstream signaling of the upd3 gene. The upd3 enhancers were analyzed in 19.2 Kb genomic regions around the upd3 gene. These upd3 genomic fragments are cloned to pH-stinger, an enhancer-testing vector containing a GFP reporter. These enhancer-testing constructs are microinjected into fly embryos and then select for transgenic lines.The GFP reporter was examined in different developmental stages. We found upd3 is expressed in the eye-antenna, lymph glands and midgut. Based on this study, the possible regulation of the upd3 gene was further elucidated during Drosophila development.