Efficient iterative CRISPR/Cas9 editing using <i>sid-1</i> co-conversion and feeding RNAi in <i>Caenorhabditis elegans</i>

We present a sid-1 loss-of-function and restoration-of-function CRISPR/Cas9 co-conversion protocol in Caenorhabditis elegans. Introducing CRISPR reagents that induce sid-1 loss-of-function can produce survivors on lethal RNAi foods while reagents that induce sid-1 restoration-of-function can be screened for restoration of visible RNAi phenotypes. Both methods efficiently reduce the pool of candidates from hundreds or thousands of F1 progeny to tens with minimal experimenter effort. Furthermore, our optimized sid-1 CRISPR design allows a high ratio of CRISPR reagents targeting the gene of interest, maximizing successful co-conversion events. The interconvertibility of the sid-1 locus readily enables this strategy to be leveraged to iteratively create complex strains with multiple gene edits.