MosTI single-copy transgene insertion in C. elegans using constitutive Cas9 expression

Abstract Transgene expression in C. elegans is an important tool for understanding regulatory elements (e.g., promoters and enhancers), for controlling cells using optogenetic effector proteins, and for editing the (epi)genome. Insertion of single-copy transgenes into well-defined safe-harbor locations can be used when consistent expression is required (e.g., to compare expression from different transgenes) or when expression is required in germ cells. Here, we describe a detailed protocol for inserting single-copy transgenes using Modular Safe-harbor Transgene Insertion (MosTI) and constitutive Cas9 expression from a co-injected plasmid.