In Chernobyl stray dogs, scientists search for genetic effects of radiation

After the Chernobyl nuclear power plant disaster in Ukraine in 1986, residents were forced to permanently evacuate, leaving their homes and, in some cases, their pets behind. Fearing that these abandoned animals could spread diseases or contaminate humans, the authorities tried to exterminate them.

And yet, a population of dogs somehow survived. They found connections with Chernobyl cleanup crews, and power plant workers who remained in the area sometimes gave them food. (During the last years, adventurous tourists also distributed documents.)

Today, hundreds of free-roaming dogs live in the area around the disaster site, known as the exclusion zone. They wander the abandoned town of Pripyat and sleep in the highly contaminated Semikhody train station.

Now, scientists have conducted the first in-depth analysis in the DNA of animals. Chernobyl dogs are genetically distinct, different from purebred dogs as well as other groups of free-breeding dogs, scientists reported Friday in Science Advances.

It is still too early to say if, or how, the radioactive environment contributed to the unique genetic profiles of Chernobyl dogs, scientists said. But the study is the first step in an effort to understand not only how long-term radiation exposure affected dogs, but also what to do to survive an environmental disaster.

“Have they acquired mutations that allow them to live and reproduce successfully in this region?” said Elaine Ostrander, a dog genomics expert at the National Human Genome Research Institute and lead author of the study. “What challenges do they face and how have they coped genetically? »

Before researchers could address these questions, they had to familiarize themselves with the canine landscape.

“There’s this area where there are different levels of radioactivity, and dogs live everywhere,” Dr. Ostrander said. “We needed to know who was who and what before we could begin our hunt for these critical mutations. »

The project is a collaboration between scientists from the United States, Ukraine and Poland, as well as the Clean Futures Fund, a US-based non-profit organization working at Chernobyl. The non-profit organization, established in 2016, began with the aim of providing healthcare and support to power plant employees, who still work in the exclusion zone.

But the organization quickly realized that The canine residents of Chernobyl I also needed help. Although the dog population boomed during the summer, it often collapsed in the winter, when food was scarce. Rage was a constant concern.

In 2017, the Clean Futures Fund began hosting veterinary clinics for local dogs, providing care, administering vaccines and spaying and neutering animals. Researchers used these clinics to collect blood samples from 302 dogs living in different locations in and around the exclusion zone.

Nearly half of the dogs lived in the immediate vicinity of the power plant, while the other half lived in the town of Chernobyl, a sparsely occupied residential area about 15 kilometers away. (A small number of samples came from dogs in Slavutych, a town built for workers evacuated from power plants, almost 30 miles away.)

Although there was some overlap between the dog populations, in general, the power plant dogs were genetically distinct from the Chernobyl city dogs, the researchers found. There appears to be little gene flow between the two groups, suggesting that they rarely interbreed. (Physical security barriers around the power plant may have helped keep the dogs apart, the researchers noted.)

“I was completely surprised by the almost complete differentiation between the two populations, by the fact that they have existed in relative isolation for quite some time,” said Timothy Mousseau, a biologist at the University of South Carolina and another lead author of the study. the study.

The researchers also traced kinship relationships, linking parents and their offspring to identify 15 different family groups. Some dog families were large and sprawling, while others were tiny, with more defined geographic territories. Three family groups shared a spent nuclear fuel storage facility, scientists found.

“I don’t think anyone has ever genetically examined a single population of free-breeding dogs at this level of detail,” said Adam Boyko, a canine geneticist at Cornell University’s College of Veterinary Medicine, who was not involved in the research. .

The study will provide a good starting point for further investigation into the effects of radiation, Dr. Boyko added. “They find where the interesting populations are,” he said, “where the interesting family groups are.”

The Power Plant Dogs and the Chernobyl City Dogs had mixed breed ancestry, but both shared portions of DNA with German Shepherds, as well as other European Shepherd breeds from around the world. ‘East. Dogs from the city of Chernobyl also had variations common in boxers and rottweilers.

These segments of shepherd DNA could provide particularly useful data in future studies, the scientists said. Comparing these sequences from the power plant dogs, Chernobyl city dogs and purebred shepherds living in non-radioactive environments could help researchers identify radiation-related changes in the genome.

“This is a unique opportunity,” said Dr. Mousseau, “a unique animal population.”


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