CRISPR-Cas13d as a molecular tool to achieve targeted gene expression knockdown in chick embryos.

The chick embryo is a classical model system commonly used in developmental biology due to its amenability to gene perturbation experiments. Pairing this powerful model organism with cutting-edge technology can significantly expand the range of experiments that can be performed. Recently, the CRISPR-Cas13d system has been successfully adapted for use in zebrafish, medaka, killifish, and mouse embryos to achieve targeted gene expression knockdown. Despite its success in other animal models, no prior study has explored the potential of CRISPR-Cas13d in the chick. Here, we present an adaptation of the CRISPR-Cas13d system to achieve targeted gene expression knockdown in the chick embryo. As proof-of-principle, we demonstrate the knockdown of PAX7, an early neural crest marker. Application of this adapted CRISPR-Cas13d technique resulted in effective knockdown of PAX7 expression and function, comparable to knockdown achieved by translation-blocking morpholino. CRISPR-Cas13d complements preexisting knockdown tools such as CRISPR-Cas9 and morpholinos, thereby expanding the experimental potential and versatility of the chick model system.