Chernobyl worms show tolerance to chronic nuclear radiation

A new study from New York University found that microscopic worms they collected in the Chernobyl exclusion zone suffered no damage to their genomes despite being exposed to radiation from the site.

The explosion of Reactor No. 4 at the Chernobyl Nuclear Power Plant on April 26, 1986, in the then Soviet Union, caused one of the most disastrous nuclear accidents in history, as it led to the release of carcinogenic radiation and radioactive residue into the environment.

Since then, the exclusion zone around the Chernobyl nuclear power plant and the nearby city of Pripyat has remained uninhabited due to residual effects of radiation.

However, animals and plants in the area continued to be exposed to radiation in this most radioactive environment on Earth.

Previous research has shown that some animal specimens from Chernobyl are physically and genetically different from their counterparts from other parts of the planet, which is why the scientific community has questioned the effect of chronic radiation on their DNA.

In the new study published in the journal PNAS, scientists reported no genetic mutations in nematodes (small worms with simple genomes and rapid reproduction) that came from areas of high and low radioactivity in the restricted area.

They said that despite being exposed to chronic radiation, the worms' DNA remained intact.

The study focused on 15 worms of the Oscheius tipulae type, known for their importance in genetic and evolutionary research.

By sequencing the genomes of these Chernobyl worms and comparing them to those of Oscheius Tipulae from other regions of the world, scientists expected to uncover genetic changes caused by radiation. However, their findings did not support this hypothesis.

Given the absence of the genetic imprint of radiation, the team devised an experiment to evaluate the worms' growth rates and their sensitivity to different types of DNA damage.

Although differences in DNA damage tolerance were observed between worm strains, these differences did not correlate with radiation levels at their collection sites, indicating that Chernobyl nematodes did not develop specific resistance to radiation.

“This does not mean that Chernobyl is safe,” says Sofia Tintori, a postdoctoral fellow in the Department of Biology at New York University. “It more likely means that nematodes are really resilient animals that can withstand extreme conditions.”

She added: “We also do not know how long each of the worms we collected had been in the area, so we cannot be sure exactly what level of exposure each worm and its ancestors received over the past four decades.”

“Now that we know which strains of Oscheius Tipulae are more sensitive or more tolerant to DNA damage, we can use these strains to study why different individuals are more likely than others to suffer the effects of carcinogens,” she explained.

The study highlights that the findings are important for understanding how DNA repair varies from one individual to another. Interestingly, it could also provide some clues about human cancer.