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Radiation-induced mutation is unlikely to have induced genetic differences between dog populations in Chornobyl City and the nearby Chornobyl Nuclear Power Plant (NPP), according to a new study in PLOS ONE from North Carolina State University and Columbia University Mailman School of Public Health. The study has implications for understanding the effects of environmental contamination on populations over time.

"According to Matthew Breen, Oscar J. Fletcher Distinguished Professor of Comparative Oncology Genetics at NC State, 'We have been studying two dog populations that are only 16 kilometers, or roughly 10 miles, apart, yet they exhibit significant genetic differences.'"

"We aim to explore whether prolonged low-level exposure to environmental toxins like radiation and lead could account for some of these disparities." Breen serves as the lead author of the research.

In earlier research, the team examined genetic variations throughout the genome and pinpointed 391 unique regions in dogs that were distinct between the two populations. Among these regions, several harbored genes linked to the repair of DNA damage. In their latest study, the researchers took a more thorough approach, exploring the dogs' genomes to uncover signs of mutations that might have built up over time.

"Initially, we placed the genetic differences between two dog populations into context, revealing that the genetics of dogs from Chornobyl City closely resembled those of dog populations in Russia, Poland, and nearby regions," explains Megan Dillon, a Ph.D. candidate at NC State and the primary author of the research.

"This allowed us to utilize the dogs from Chornobyl City as a control group for comparison with the dogs from the nuclear power plant."

The research team initially focused on identifying differences at the chromosomal level, subsequently narrowing their investigation to smaller genomic intervals, and finally examining variations at the single nucleotide level. Their goal was to uncover abnormalities and signs of accumulated mutations in germ line DNA—alterations that take place in the DNA of reproductive cells and are inherited from parents to their descendants over generations.

"Breen explains, 'It's similar to utilizing the zoom feature on your phone's camera to capture finer details; we begin with a broad perspective of a subject and then focus in closely.'"

"It is understood that high levels of radiation exposure can lead to instability starting from the chromosomal level. Although this dog population is over 30 generations separated from the dogs that lived through the 1986 disaster, any mutations that might have provided a survival benefit to those original dogs would likely still be identifiable. However, we did not observe any such evidence in these dogs."

Although researchers did not find any evidence of genetic mutation, they emphasize that this does not exclude the possibility that selective pressures may account for the differences observed between the two dog populations.

"Dillon explains that, in human context, this situation resembles examining a population that has lived hundreds of years after the disaster occurred."

"It’s conceivable that the dogs that lived long enough to reproduce possessed certain genetic traits that enhanced their survival chances. This suggests that there might have been significant selective pressure initially, and subsequently, the dogs at the power plant stayed isolated from the urban population. Exploring this question is a crucial next step that we are currently pursuing."

The researchers highlight that these results are just a fragment of the broader context regarding how negative environmental factors can impact the health of both dogs and humans.

"While many consider the Chornobyl nuclear disaster to be a localized radiological event in a remote part of Ukraine, the health risks extend far beyond that," explains Norman Kleiman, a co-author and professor of environmental health sciences at Columbia University School of Public Health. "This is attributed to the various other hazardous substances, such as heavy metals, lead dust, pesticides, and asbestos, that were dispersed into the environment during the cleanup and remediation efforts spanning over thirty years."

"Although no one currently resides at the NPP or in Pripyat, prior to the Russian invasion, thousands of individuals were still employed there daily, engaged in remediation and construction efforts in the vicinity," Kleiman explains. "Examining companion animals such as these dogs provides insight into the potential health hazards that people may encounter."

In addition to looking at the genetics of the dogs, the team also recently identified differences in ticks recovered from the dogs at the power plant and Chornobyl City and the prevalence of the pathogens they transmit. These results, published in the journal Parasites and Vectors, may reflect differential exposures to both ticks and microbes at the two locations.

Kleiman emphasized, "The significance of ongoing research into the environmental health implications of major disasters like this cannot be understated. With our societies becoming more technological and industrialized, it is inevitable that we will face similar disasters in the future. We must comprehend the potential health hazards and identify the most effective ways to safeguard individuals."

More information: Megan N. Dillon et al, Is increased mutation driving genetic diversity in dogs within the Chornobyl exclusion zone?, PLOS ONE (2024). DOI: 10.1371/journal.pone.0315244

Megan N. Dillon et al, Contrasting pathogen prevalence between tick and dog populations at Chornobyl, Parasites & Vectors (2024). DOI: 10.1186/s13071-024-06563-4

Supplied by North Carolina State University

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