A novel conditional ZsGreen-expressing transgenic reporter rat strain for validating Cre recombinase expression.

The Cre/loxP recombination system has revolutionized the ability to genetically manipulate animal genomes in order to conditionally control gene expression. With recent advances in genome editing, barriers to manipulating the rat genome have been overcome and it is now possible to generate new rat strains (Cre drivers) in which Cre recombinase expression is carefully controlled temporally and/or spatially. However, the ability to evaluate and characterize these Cre driver strains is limited by the availability of reliable reporter rat strains. Here, we describe the generation and characterization of a new transgenic rat strain in which conditional expression of the ZsGreen fluorescent protein gene requires the presence of exogenous Cre recombinase. Breeding Cre-expressing rat strains to this stable ZsGreen reporter strain provides an ideal method for validating new rat Cre driver lines and will greatly accelerate the characterization pipeline.