The goal of the Transgenics Unit (TU) is to help research groups at the IGC by generating genetically modified animals required for their research activities. Currently, our services include the introduction of a wide spectrum of genetic modifications into the mouse and Drosophila genomes. Our work with mice includes: Production of transgenic animals by pronuclear DNA injection using both conventional expression constructs and Bacterial Artificial Chromosomes (BACs). We generate transgenic mice in various genetic backgrounds, including C57BL/6. Introduction of targeted modifications into endogenous genomic loci both following conventional embryonic stem (ES) cell-mediated approaches and with the CRISPR/Cas9 technology. In all cases, the researchers provide the DNA constructs, gRNAs or ES cells. The TU staff then performs all microinjections and surgical procedures required for the production of the mutant mice. We deliver founders or chimeras that are then further crossed and analyzed by the requesting researchers. Our work with Drosophila melanogaster includes: - A microinjection service to generate transgenic or mutant flies, via the p-element, ΦC31 or the CRISPR/Cas9 methods. Our injections are normally performed on Drosophila melanogaster but we also inject eggs from other Drosophila or even other insect species. - A microinjection service for purposes other than the production of transgenic flies (e.g. Wolbachia transfer). The researchers provide the constructs to be injected and we deliver either adult flies resulting from the injections, leaving to the researchers the production of stable transformants, or, with additional costs, we also deliver stable transformants to the user, either as homozygous or balanced. We work together with the researchers throughout the different stages of the project to make sure that we produce genetically modified animals that best meet the specific requirements of their research activities. We discuss with the researchers the different alternatives and help them to select the best strategy for their specific experimental approach. In addition, we advise on the design of the transgenic and targeting constructs, supply basic reagents that facilitate their production and provide guidance on the production of stable transformants and screening strategies that simplify future work with the mutant strains. Our main goal is to cover the needs of the research groups at the IGC but under specific circumstances we can also produce genetically modified animals for external users.