Mutagens, whether endogenous or exogenous, naturally occurring or anthropogenic, are present in our environment and lead to DNA lesions in cells.  Of the tens of thousands of DNA lesions formed on average in each human nucleus each day, the vast majority are corrected by our DNA repair machinery without incident. Even so, it is well established that heritable genetic variants in DNA repair components can contribute to cancer, birth defects, premature aging, and neurological defects.

In April 1986, two explosions at the Chernobyl Nuclear Power Plant transformed the surrounding region into the most  radioactive landscape known on the planet. The Chernobyl Exclusion Zone (CEZ) presents an opportunity to test whether chronic radiation exposure selects for an adaptive response in DNA repair mechanisms or mutagen tolerance more broadly. Nematodes are an ideal animal system for such an investigation, as they can reliably be collected from a broad range of environments, have small genomes and short generation times that suit them to experimental genetics and studies of natural variation, allowing hypotheses generated in the field to be tested directly in the lab. In their new study titled "Environmental radiation exposure at Chornobyl has not systematically affected the genomes or chemical mutagen tolerance phenotypes of local worms", Dr. Tim Mousseau and his colleagues led by Drs. Sofia Tintori and Matthew Rockman from the Department of Biology and Center for Genomics & Systems Biology at New York University collected, cultured, and cryopreserved 298 wild nematode isolates from areas varying in radioactivity within the CEZ. They sequenced and assembled genomes de novo for 20 Oscheius tipulae strains, analyzed their genomes for evidence of recent mutation acquisition in the field, and observed no evidence of an association between mutation and radioactivity at the  sites of collection. Multigenerational exposure of each of these strains to several chemical mutagens in the lab revealed that strains vary heritably in tolerance to each mutagen, but mutagen tolerance cannot be predicted based on the radiation levels at collection sites, and Chernobyl isolates were not systematically more resistant than strains from undisturbed habitats.