Use of GAL/UAS to Assay Enhancer Activity within Defined DNA Fragments in Drosophila melanogaster
Mentor:Rahul Warrior, Associate Professor of Developmental and Cell Biology , University of California, Irvine
Enhancers are DNA fragments that control the expression of genes so that they are turned on and off in specific patterns at different times during development. They are frequently located flanking the transcriptional start site of a gene. This project’s objective was to test seven DNA fragments from the Drosophila melanogaster genome for enhancer activity. Using the GAL4/UAS system, transgenic fly stocks were obtained, each containing DNA fragments flanking the genes brinker, maverick, and vesicular glutamate transporter; these DNA fragments drove the expression of GAL4, a transcriptional activator protein. The fly stocks were subsequently mated with other transgenic flies containing the UAS-GFP transgene, producing progeny with both GAL4 and UAS-GFP. As a result, GAL4 proteins bind to UAS, activating transcription of GFP and making any expression patterns controlled by the DNA fragments visible. Results were acquired through dissection, florescent microscopy, and camera imaging. Six out of seven tested DNA fragments demonstrated enhancer activity as seen in specific GFP expression patterns occurring in various imaginal discs and anatomical regions of the larval/adult fly. The DNA fragment flanking the maverick gene featured no GFP expression and thus no enhancer activity. All in all, this experiment will prove useful in demonstrating the transcriptional regulatory properties of enhancers, an aspect crucial to proper development in numerous organisms.