Figure 3.

Nickase-based homologous recombination enhanced by recOfar factors (NEO) mediated gene editing in zebrafish. The genome editing strategy is called nickase-based homologous recombination enhanced by recofar factors (NEO). The bacterial RecA protein together with RecO, RecR, and RecF factors can enhance accurate HR-KI induced by trans-dual nicks (two cooperative nicks induced on the complementary strands) or cis-dual nicks (both nicks on a same strand) in zebrafish. Furthermore, the NEO system can enable KI of >5.5-kb-long DNA cassettes into the zebrafish genome. In addition, both on-target and off-target indels that are prevalent when conventional Cas9 strategies are adopted could be substantially reduced via NEO in zebrafish. The upward yellow arrow indicates an increase in HR-KI efficiency. The downward yellow arrow indicates a decrease in the on-target and off-target indel count ratio.