A recent study published in PLOS ONE by researchers from North Carolina State University and Columbia University’s Mailman School of Public Health has found that radiation-induced mutations are unlikely to cause genetic differences between dog populations in the city of Chernobyl and the neighboring Chernobyl Nuclear Power Plant (NPP). This study is of great significance for understanding the long-term effects of environmental pollution on population.
Matthew Breen, the Oscar J. Fletcher Distinguished Professor of Comparative Tumor Genetics at North Carolina State University and corresponding author of the study, said, “We’ve been working with two breeds of dogs that are genetically distinct even though they are only 16 kilometers (about 10 miles) apart. Our aim was to find out whether long-term low-level exposure to environmental toxins, such as radiation and lead, could explain these differences.”
Previously, the team analyzed genetic variation across the entire genome and identified 391 abnormal regions between the two populations. Some of these regions contain genes involved in DNA damage repair. In the current study, the researchers looked deeper into the dogs’ genomes to look for signs of mutations that may have accumulated over time.
Megan Dillon, a PhD candidate at North Carolina State University and lead author of the study, explained: “First, we assessed the extent of genetic differences between the two dog species. We found that dogs in the city of Chernobyl are genetically very similar to dogs in Russia, Poland and surrounding areas. So we can use dogs from Chernobyl as a representative control group to compare with dogs from the nuclear power plant.”
The researchers started looking for differences at the chromosomal level, then moved on to small genomic intervals, and finally examined single-nucleotide variants. The research team had been looking for evidence of abnormal and accumulated germline DNA mutations, which are changes in the DNA of germ cells that are passed from parent to offspring over time.
Brin likens the process to using the zoom function of a phone camera. “We start with a broad theme and then gradually zoom in on more details. We know that high doses of radiation exposure can cause instability starting at the chromosomal level. Even if these dogs were 30 or more generations removed from the dogs present in the 1986 disaster, they would likely still be detectable if the mutation provided a survival advantage to the original dog. However, we found no such evidence in these dogs.”
Although no evidence of genetic mutations was found, the researchers note that this does not rule out the role of selection pressure in explaining the differences between the two dog populations.
Dillon said: “From a human perspective, it’s like studying a population that is centuries removed from the time of the disaster. It’s possible that dogs that survive long enough already have genetic traits that improve survival. So maybe there was strong selection pressure at first, and then the power plant dogs were isolated from the urban population. Investigating this issue is an important next step in what we are currently doing.”
The researchers stress that these findings are part of a broader understanding of the role that adverse environmental exposures play in canine and human health.
Norman Kleiman, a professor of environmental health sciences at Columbia University School of Public Health and one of the study’s co-authors, said: “Most people think of the Chernobyl nuclear accident as a radiation disaster in abandoned areas of Ukraine, but the potential adverse health effects are profound. This is because large amounts of other toxins, such as heavy metals, lead powder, pesticides and asbestos, were released into the environment during the 30-year-long clean-up and remediation effort.”
“While no one lives in the nuclear power plant or Pripyat anymore, before the Russian invasion, thousands of people continued to work on nearby restoration and construction projects every day,” he added. Studying companion animals like dogs can give us insight into the adverse health risks that people may face.”
In addition to analyzing the dogs’ genes, the team recently discovered differences in ticks collected from dogs at the nuclear power plant and in the city of Chernobyl, as well as the prevalence of pathogens they spread. These results, published in the journal Parasites and Vectors, may reflect different levels of exposure to ticks and microbes at the two sites.
Kleiman stressed that “the importance of continuing to study the environmental health aspects of large-scale disasters like this cannot be overstated.” Given our increasingly technological and industrial society, there will undoubtedly be other similar disasters in the future, and we need to understand the potential health risks and how best to protect people.”
The study was co-authored by Allison Dickey, a research scholar at North Carolina State University; Reed Roberts, associate professor of biological sciences at North Carolina State University; Jennifer Betz is a veterinarian with Visiting Veterinarians International; And Timothy Mousseau, a professor of biological sciences at the University of South Carolina.
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