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 nonradioactively 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.