Public Library of Science, PLoS Genetics, 2(17), p. e1009385, 2021
DOI: 10.1371/journal.pgen.1009385
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Gene drive elements promote the spread of linked traits, providing methods for changing the composition or fate of wild populations. Drive mechanisms that are self-limiting are attractive because they allow control over the duration and extent of trait spread in time and space, and are reversible through natural selection as drive wanes. Self-sustainingCleave and Rescue(ClvR) elements include a DNA sequence-modifying enzyme such as Cas9/gRNAs that disrupts endogenous versions of an essential gene, a tightly linked recoded version of the essential gene resistant to cleavage (theRescue), and a Cargo.ClvRspreads by creating loss-of-function (LOF) conditions in which those withoutClvRdie because they lack functional copies of the essential gene. We use modeling to show that when theRescue-Cargo and one or both components required for LOF allele creation (Cas9 and gRNA) reside at different locations (splitClvR), drive ofRescue-Cargo is self-limiting due to a progressive decrease in Cas9 frequency, and thus opportunities for creation of LOF alleles, as spread occurs. Importantly, drive strength and duration can be extended in a measured manner—which is still self-limiting—by moving the two components close enough to each other that they experience some degree of linkage. With linkage, Cas9 transiently experiences drive by hitchhiking withRescue-Cargo until linkage disequilibrium between the two disappears, a function of recombination frequency and number of generations, creating a novel point of control. We implement splitClvRinDrosophila, with key elements on different chromosomes. Cargo/Rescue/gRNAs spreads to high frequency in a Cas9-dependent manner, while the frequency of Cas9 decreases. These observations show that measured, transient drive, coupled with a loss of future drive potential, can be achieved using the simple toolkit that make upClvRelements—Cas9 and gRNAs and aRescue/Cargo.