More errors occur in DNA replication during times of stress when resources are scares, scientists at the University of Toronto have found. This contradicts previous thought on the subject, which stated that cells use proofreading enzymes to copy the DNA code with high fidelity.

The study, led by Grant Brown of the University of Toronto, was published in the Molecular Cell journal. Initially looking at DNA replication in yeast cells raised under a limited supply of nucleotide bases, the scientists discovered that such stressful circumstances create replication errors in much larger quantities than previously thought.

They found that the environmental scarcity led cells to use another, more fallible type of DNA polymerase, thought previously to only belong to cell repair machinery activated following physical damage.

Should this mechanism prove true in humans as well as yeast, it could have big implications for the study of cancer. Due to their fast proliferation, cancer cells often run out of nucleotide “fuel”. Based on the new research, this mechanism in cancer could mean the error-prone repair process could be creating poorly-replicated DNA, whose mutations could be helping cancer survive.