It was about 10 years ago that scientists discovered that low energy electrons could damage the DNA. However, the medical community ignored the indirect evidence, said Deepak Mathur, senior professor at the Tata Institute of Fundamental Research (TIFR).
Since then, experiments conducted on thin films of DNA have indicated that low energy electrons may cause single strand or double strand breaks in the DNA.
The five-member Mumbai team headed by Mathur began its research in 2008 and performed the experiments in the liquid phase - a mixture of water and DNA, which is closer to the composition in the human body that comprises 70% water.
Researchers shot ultra-short pulses of high-intensity laser light through a quartz tube containing a mixture of DNA molecules and water. The strong laser light created hot plasma (like in the sun) and broke water molecules into various constituents including electrons and hydroxyl (OH) radicals, which reacted with the DNA to alter it.
The DNA, which in its original form resembled a ball of wool, on exposure to the laser beam got fragmented and became a linear entity showing breaks in the DNA structure.
"Through a series of more experiments, we found that OH radicals were four times more effective in inducing damage than electrons," said Mathur.
"If the DNA strand is broken, it is prone to getting chewed up by the enzymes present in the cell. Therefore, there are chances of losing an entire chromosome," said Jacintha D'Souza, co-researcher from Mumbai University.
Researchers said the findings would have implications in reducing the damage caused by lasers used in biomedical applications, genetic engineering and biotechnology. For instance, there is a technique being developed to deliver foreign genetic material into cells by transiently altering the cell permeability by exposing single cells to sharply-focused laser light.