Basics of genome editing technology and its application in livestock species

<jats:title>Contents</jats:title><jats:p>In the last decade, the research community has witnessed a blooming of targeted genome editing tools and applications. Novel programmable <jats:styled-content style="fixed-case">DNA</jats:styled-content> nucleases such as zinc finger nucleases (<jats:styled-content style="fixed-case">ZFN</jats:styled-content>s), transcription activator‐like endonucleases (<jats:styled-content style="fixed-case">TALEN</jats:styled-content>s) and the clustered regularly interspaced short palindromic repeats/Cas9 system (<jats:styled-content style="fixed-case">CRISPR</jats:styled-content>/Cas9) possess long recognition sites and are capable of cutting <jats:styled-content style="fixed-case">DNA</jats:styled-content> in a very specific manner. These <jats:styled-content style="fixed-case">DNA</jats:styled-content> nucleases mediate targeted genetic alterations by enhancing the <jats:styled-content style="fixed-case">DNA</jats:styled-content> mutation rate via induction of double‐strand breaks at a predetermined genomic site. Compared to conventional homologous recombination‐based gene targeting, <jats:styled-content style="fixed-case">DNA</jats:styled-content> nucleases, also referred to as Genome Editors (<jats:styled-content style="fixed-case">GE</jats:styled-content>s), can increase the targeting rate around 10,000‐ to 100,000‐fold. The successful application of different <jats:styled-content style="fixed-case">GE</jats:styled-content>s has been shown in a myriad of different organisms, including insects, amphibians, plants, nematodes and several mammalian species, including human cells and embryos. In contrast to all other <jats:styled-content style="fixed-case">DNA</jats:styled-content> nucleases, that rely on protein–<jats:styled-content style="fixed-case">DNA</jats:styled-content> binding, <jats:styled-content style="fixed-case">CRISPR</jats:styled-content>/Cas9 uses <jats:styled-content style="fixed-case">RNA</jats:styled-content> to establish a specific binding of its <jats:styled-content style="fixed-case">DNA</jats:styled-content> nuclease. Besides its capability to facilitate multiplexed genomic modifications in one shot, the <jats:styled-content style="fixed-case">CRISPR</jats:styled-content>/Cas is much easier to design compared to all other <jats:styled-content style="fixed-case">DNA</jats:styled-content> nucleases. Current results indicate that any <jats:styled-content style="fixed-case">DNA</jats:styled-content> nuclease can be successfully employed in a broad range of organisms which renders them useful for improving the understanding of complex physiological systems such as reproduction, producing transgenic animals, including creating large animal models for human diseases, creating specific cell lines, and plants, and even for treating human genetic diseases. This review provides an update on <jats:styled-content style="fixed-case">DNA</jats:styled-content> nucleases, their underlying mechanism and focuses on their application to edit the genome of livestock species.</jats:p>