Optimized CRISPR/Cas tools for efficient germline and somatic genome engineering in Drosophila

Area of Science:

• Molecular Biology
• Genetics
• Developmental Biology

Background:

• The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) system is a revolutionary genome engineering tool.
• Efficient and precise genome manipulation is crucial for understanding gene function and organismal development.

Purpose of the Study:

• To create a high-efficiency CRISPR/Cas toolbox for Drosophila melanogaster genome engineering.
• To optimize Cas9 expression and guide RNA (gRNA) delivery for robust gene targeting.
• To demonstrate the utility of the toolbox for various genome editing applications, including mutagenesis and precise editing.

Main Methods:

• Development of transgenic Cas9 fly lines with different expression patterns (ubiquitous and germ-line-restricted).
• Design and testing of versatile gRNA expression plasmids utilizing various U6 snRNA promoters, including the U6:3 promoter.
• Application of the CRISPR/Cas system for gene targeting, offset nicking-based mutagenesis, and homology-directed repair (HDR) with donor templates.

Main Results:

• Achieved high gene targeting transmission rates (25-100%) for essential and nonessential genes.
• Demonstrated efficient precise genome editing via HDR, obviating the need for selection markers.
• Successfully applied CRISPR/Cas for biallelic targeting in somatic cells to reveal loss-of-function phenotypes.

Conclusions:

• The developed CRISPR/Cas toolbox significantly enhances genome engineering capabilities in Drosophila melanogaster.
• This system facilitates rapid evaluation of gene function and precise genomic modifications.
• The tools are suitable for high-throughput genetic screening and complex genome editing applications.