Achieving single nucleotide sensitivity in direct hybridization genome imaging.

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Direct visualization of point mutations in situ is crucial for understanding genetic diseases and nuclear biology.
• Existing methods may lack the sensitivity to differentiate single base pair differences.
• Accurate detection of point mutations is essential for various biological and medical applications.

Purpose of the Study:

• To describe a novel direct hybridization genome imaging method with single-nucleotide sensitivity.
• To enable the visualization and differentiation of wild-type and mutant DNA sequences in situ.
• To apply this method for identifying specific genetic modifications in cellular populations.

Main Methods:

• Developed single guide genome oligopaint via local denaturation fluorescence in situ hybridization (sgGOLDFISH).
• Leveraged the eSpCas9(1.1) variant and a specifically designed guide RNA for targeted DNA cleavage.
• Utilized local denaturation and probe binding to differentiate sequences based on Cas9 cleavage efficiency.

Main Results:

• sgGOLDFISH demonstrated single-nucleotide sensitivity, differentiating wild-type and mutant sequences with a single base pair difference.
• Successfully identified base-editor-modified and unmodified progeroid fibroblasts from a mixed population.
• Validated findings using progerin immunofluorescence and showed accurate sub-nuclear localization of point mutations.

Conclusions:

• sgGOLDFISH provides a powerful tool for direct visualization and differentiation of point mutations in situ.
• The method offers high sensitivity and specificity for genomic analysis at the single-nucleotide level.
• This technique has significant potential for applications in genetic disease research and diagnostics.