Question

What is the split gal4 system? Why is it needed to label some cell types? Describe an experiment that combines split gal4 with scRNA-seq to precisely define cell identities in the drosophila brain. Describe the protocol of the experiment in detail.

Answer 1

The GAL4-UAS system is a biochemical method used to study gene expression and function in organisms such as the fruit fly. It has also been adapted to study receptor chemical-binding functions in vitro in cell culture. It is considered a powerful technique for studying the expression of genes.The system has two parts: the Gal4 gene, encoding the yeast transcription activator protein Gal4, and the UAS (Upstream Activation Sequence), an enhancer to which GAL4 specifically binds to activate gene transcription.

The Gal4/UAS system

Gal4 is a transcriptional activator that binds to UAS enhancer sequences found in DNA. It then recruits transcription machinery to the site to induce gene expression. Thus, genes and siRNA encoded downstream of the UAS sequence are only expressed when Gal4 is expressed.

Protocol :Emergent properties and external factors (population-level and ecosystem-level interactions, in particular) play important roles in mediating ecologically-important endpoints, though they are rarely considered in toxicological studies. D. melanogaster is emerging as a toxicology model for the behavioral, neurological, and genetic impacts of toxicants, to name a few. More importantly, species in the genus Drosophila can be utilized as a model system for an integrative framework approach to incorporate emergent properties and answer ecologically-relevant questions in toxicology research. The aim of this paper is to provide a protocol for exposing species in the genus Drosophila to pollutants to be used as a model system for a range of phenotypic outputs and ecologically-relevant questions. More specifically, this protocol can be used to 1) link multiple biological levels of organization and understand the impact of toxicants on both individual- and population-level fitness; 2) test the impact of toxicants at different stages of developmental exposure; 3) test multigenerational and evolutionary implications of pollutants; and 4) test multiple contaminants and stressors simultaneously.