Willem J Laursen, Rachel Busby, Tatevik Sarkissian, Elaine C Chang, Paul A Garrity

The advent of CRISPR/Cas9-mediated genome editing has expanded the range of animals amenable to targeted genetic analysis. This has accelerated research in animals not traditionally studied using molecular genetics. However, studying genes essential for reproduction or survival in such animals remains challenging, as they lack the tools that aid genetic analysis in traditional genetic model organisms. We recently introduced the use of distinguishably marked knock-in pairs (DMKPs) as a strategy for rapid and reliable genotyping in such species. Here we show that DMKPs also facilitate the maintenance and study of mutations that cannot be maintained in a homozygous state, a group which includes recessive lethal and sterile mutations. Using DMKPs, we disrupt the zero population growth (zpg) locus in Drosophila melanogaster and in the dengue vector mosquito Aedes aegypti. In both species, DMKPs enable the maintenance of zpg mutant strains and the reliable recovery of zpg mutant animals. Male and female gonad development is disrupted in fly and mosquito zpg mutants, rendering both sexes sterile. In Aedes aegypti, zpg mutant males remain capable of inducing a mating refractory period in wild-type females and of competing with wild-type males for mates, properties compatible with zpg serving as a target in mosquito population suppression strategies. DMKP is readily generalizable to other species amenable to CRISPR/Cas9-mediated gene targeting, and should facilitate the study of sterile and lethal mutations in multiple organisms not traditionally studied using molecular genetics.