Subdenaturing (pH 11.1) filter elution: more sensitive quantification of DNA double-strand breaks

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• DNA double-strand breaks (DSBs) are critical lesions requiring accurate quantification.
• Standard neutral filter elution assays (pH 7.2/9.6) detect DSBs at 5-10 Gy.
• Agarose gel electrophoresis detects DSBs at 1 Gy but has limitations in measuring rejoining.

Purpose of the Study:

• To develop a more sensitive method for quantifying DNA double-strand breaks (DSBs).
• To validate a modified filter elution assay for low-dose DSB detection and rejoining measurements.

Main Methods:

• Modified neutral filter elution assay at pH 11.1.
• Comparison with standard filter elution (pH 9.6) and agarose gel electrophoresis.
• Induction of DSBs using restriction endonuclease HaeIII in permeabilized cells.

Main Results:

• The pH 11.1 filter elution assay detects DSBs induced by as little as 1 Gy of ionizing radiation.
• This method is insensitive to single-strand breaks induced by hydrogen peroxide.
• The assay demonstrates a five-fold increase in sensitivity without significantly converting alkali-labile sites to DSBs.

Conclusions:

• The pH 11.1 filter elution assay significantly enhances sensitivity for DSB detection.
• This validated assay is suitable for low-dose measurements of DSB induction and rejoining in cells.
• The improved assay provides a more precise tool for studying DNA damage and repair mechanisms.