A gene-specific T2A-GAL4 library for Drosophila

Abstract

We generated a library of ~1000 <i>Drosophila</i> stocks in which we inserted a construct in the intron of genes allowing expression of <i>GAL4</i> under control of endogenous promoters while arresting transcription with a polyadenylation signal 3' of the GAL4. This allows numerous applications. First, ~90% of insertions in essential genes cause a severe loss-of-function phenotype, an effective way to mutagenize genes. Interestingly, 12/14 chromosomes engineered through CRISPR do not carry second-site lethal mutations. Second, 26/36 (70%) of lethal insertions tested are rescued with a single <i>UAS-</i>cDNA construct. Third, loss-of-function phenotypes associated with many <i>GAL4</i> insertions can be reverted by excision with <i>UAS-flippase</i>. Fourth, <i>GAL4</i> driven <i>UAS-GFP/RFP</i> reports tissue and cell-type specificity of gene expression with high sensitivity. We report the expression of hundreds of genes not previously reported. Finally, inserted cassettes can be replaced with <i>GFP</i> or any DNA. These stocks comprise a powerful resource for assessing gene function.