crispr molecular mechanisms

The CRISPR-Cas9 system is a powerful genetic modification technique used in Drosophila melanogaster to induce targeted mutations. It is based on the Cas9 enzyme, a nuclease capable of cutting DNA at a precise location with the aid of a guide RNA (sgRNA).

Steps in the microinjection process :

1. Preparation of components :

   • A guide RNA (sgRNA) designed to target a specific genome sequence.The Cas9 enzyme, either as mRNA or as a protein pre-assembled with the sgRNA (RNP complex).

2. Microinjection into Drosophila embryos at syncytial stage (before cell membrane formation).

3. Cas9 action :

• Cas9 cuts DNA at the target site.

• The cell attempts to repair the cut by NHEJ (Non-Homologous End Joining), often introducing deleterious mutations, or by HDR (Homology-Directed Repair) in the presence of an exogenous DNA fragment serving as a template for editing.