Generation of digoxigenin-incorporated probes to enhance DNA detection sensitivity

Telomere length in humans has been correlated with cancer and age-related diseases. The standard method to measure telomere length relies on Southern blot analysis with radioactively or non-radioactively labeled probes containing several telomeric DNA repeats. However, this approach requires relatively large amounts of genomic DNA, making it difficult to measure telomere length when a limited amount of sample is available. Here, we describe a non-radioactive labeling method that uses 3' fill-in combined with lambda exonuclease digestion to incorporate one or more digoxigenin (DIG) molecules into bridged nucleic acid (BNA)-containing oligonucleotides (ONTs). Using our method, we were able to generate probes to detect both C- and G-rich telomeric DNA strands. Compared with commercially available DIG-labeled telomere probes, probes generated using this new approach significantly enhance the sensitivity of telomere length measurements.