What “Chernobyl dogs” can tell us about surviving in contaminated environments

In a first step toward understanding how dogs—and perhaps humans—might adapt to intense environmental stressors such as exposure to radiation, heavy metals or toxic chemicals, researchers discovered that two groups of dogs living in the Chernobyl exclusion zone, one at the site of the former Chernobyl reactors and another 16.5 km away in the city of Chernobyl, showed significant genetic differences between them.

The results show that these are two different populations that rarely interbreed. While previous studies have focused on the effects of the Chernobyl nuclear power plant disaster on various species of wildlife, this is the first investigation into the genetic makeup of stray dogs living near the Chernobyl nuclear power plant.

The Chernobyl nuclear power plant disaster in 1986 displaced more than 300,000 people living nearby and led to the creation of an Exclusion Zone, a “no man’s land” of about 30 km radius surrounding the destroyed reactor complex.

While a massive steam explosion that released massive amounts of ionizing radiation into the air, water, and ground was the immediate cause of the disaster, radiation exposure is not the only environmental hazard resulting from the disaster. Chemicals, toxic metals, pesticides and organic compounds left behind by long-term clean-up efforts and from abandoned and decaying structures, including the nearby abandoned city of Pripyat and the Duga-1 military base, all contribute to an ecological and environmental disaster.

“Somehow, two small populations of dogs managed to survive in this highly toxic environment,” noted Norman J. Kleiman, Ph.D., assistant professor of Environmental Health Sciences at the Columbia Mailman School of Public Health, and co-author. “In addition to sorting out the population dynamics in these dogs at both sites, we have taken the first steps toward understanding how chronic exposure to multiple environmental hazards may have affected these populations.”

“The key question here is: does an environmental disaster of this magnitude have a genetic impact on life in the region?” says Matthew Breen, Oscar J. Fletcher Distinguished Professor of Comparative Oncology Genetics at NC State, and a corresponding author. “And we have two populations of dogs living in and near the site of a major environmental disaster that may provide key information to help us answer that question.”

Previous research by the co-authors, led by NIH collaborators, used a much smaller set of genetic variants, but a larger number of dogs, to show that the two populations were separate and that each had complex family structures.

In this parallel study, the team analyzed the dog’s DNA samples with four times the number of genetic variants, which provided a closer look at the genomes. In addition to confirming that the two populations are indeed genetically distinct, the team was also able to identify 391 outlying regions in the dog genome that differed between the dogs living in the two locations.

“Think of these areas as markers, or road signs, on a highway,” says Breen. “They identify regions within the genome where we should look more closely at nearby genes. In addition, some of these markers point to genes associated with genetic repair; specifically, with genetic repair after exposures similar to those experienced by the dogs at Chernobyl .”

He went on to say that “at this stage we cannot say with certainty that any genetic alterations are in response to multigenerational and complex exposures; we have much more work to do to determine if this is the case.”

“The question we now have to answer is why are there striking genetic differences between the two populations of dogs?” says Megan Dillion, Ph.D. candidate at NC State and lead author of the published study. “Are the differences simply due to genetic drift or are they due to the unique environmental stressors at each location?”

“The dog is kind of a guard,” says Breen. “By exploring whether or not the genetic changes we identified in these dogs are the response of the dog genome to the exposures the populations have faced, we may be able to understand how dogs survived in such a hostile environment and what this might mean for any population – animal or human – experiencing similar exposures’.

“Although it has been 37 years since the accident, the half-life of radioisotopes of ~30 years means that the risk of radiation exposure is still very real,” notes Kleiman, who is also the director of Columbia University’s Radiation Safety. Officer training seminar.

“When radiation exposure is combined with a complex toxic chemical mixture of uncertain composition, very real human health concerns are raised for the thousands of people who continue to work in the Exclusion Zone for the ongoing cleanup efforts as well as two newly constructed nuclear fuels. reprocessing plants’.

“Understanding the genetic and health effects of these chronic exposures in dogs will enhance our broader understanding of how these types of environmental hazards can affect humans and how best to mitigate health risks.”

The survey appears at Canine Medicine and Genetics.