CRISPR/Cas Gene Editing System in the Silkworm, Bombyx mori

The clustered, regularly interspaced short palindromic repeats (CRISPR) and their cooperation with CRISPR-associated (Cas) genes has become a powerful genome engineering tool. The CRISPR/Cas system was discovered as a part of the adaptive immune system in bacteria and archaea to defend from plasmids and phages. CRISPR/Cas9 protein has become the most favored editing tool in recent years. CRISPR/Cas restriction system involves the restriction of endonuclease enzyme guided by a hybrid strand of RNA consisting of CRISPR RNA (crRNA) and trans-activating RNA (tracrRNA) that results in a gene knock-out or knock-in followed by non-homologous end joining (NHEJ) and homology-directed repair (HDR). Owing to its efficiency, specificity, and reproducibility, apart from its application in biotechnology, CRISPR/Cas has been explored for its therapeutic potential in several human diseases. However, CRISPR/Cas also has many limitations. To overcome some of the shortcomings of the Cas9 system, many alternative systems also have been developed. Silkworm, Bombyx mori is a model laboratory tool for many genetic experiments. Silkworm is also an important commercial organism. In the present chapter, an overall understanding of the CRISPR/Cas genome editing tools, various terminologies associated with the technology, and major work conducted in the silkworm, Bombyx mori, are discussed.