Figure 1. Targeted mutagenesis of zebrafish genes with zinc-finger nucleases (ZFNs).
Two ZFNs that target the locus of interest are generated through rational design and screening. mRNAs encoding the ZFNs are injected into zebrafish embryos at the one-cell stage. After cleavage of the target sequence, the endogenous repair machinery can religate the DNA through nonhomologous end joining, which often adds or deletes nucleotides at the cleavage site.