TUNEL Labeling to Detect Double-stranded DNA Breaks in Caenorhabditis elegans Gonads

Analysis of DNA double strand breaks (DSBs) is important for understanding dyshomeostasis within the nucleus, impaired DNA repair mechanisms, and cell death. In the C. elegans germline, DSBs are important indicators of all three above-mentioned conditions. Although multiple methods exist to assess apoptosis in the germline of C. elegans, direct assessment of DSBs without the need for a reporter allele or protein-specific antibody is useful. As such, unbiased immunofluorescent approaches can be favorable. This protocol details a method for using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) to assess DNA DSBs in dissected C. elegans germlines. Germlines are co-labeled with DAPI to allow for easy assessment of DNA DSBs. This approach allows for qualitative or quantitative measures of DNA DSBs. Graphic abstract: Schematic for TUNEL labeling of C. elegans germlines.