Efficient genome editing in zebrafish using a CRISPR-Cas system

Clustered regularly interspaced short palindromicrepeats ( CRISPR)/ CRISPR-associated (Cas) systems have evolved in bacteria and archaeaas a defense mechanism to silence foreign nucleic acids of viruses and plasmids. Recent work has shown that bacterial type II CRISPRsystems can be adapted to create guide RNAs(gRNAs) capable of directing site-specific DNA cleavage by the Cas9 nucleasein vitro. Here we show that this system can function in vivo to induce targeted genetic modifications in zebrafish embryos with efficiencies comparable to those obtained using ZFNs and TALENs for the same genes. RNA-guided nucleasesrobustly enabled genome editingat 9 of 11 different sites tested, including two for which TALENs previously failed to induce alterations. These results demonstrate that programmable CRISPR/Cas systems provide a simple, rapid, and highly scalable method for altering genes in vivo, opening the door to using RNAguided nucleasesfor genome editingin a wide range of organisms.