Sao Paulo
A study found that dogs living near the Chernobyl disaster area in Ukraine are genetically different from those living further from the high radioactivity area, indicating possible effects of radioactive exposure over the years.
The analysis was able to identify at least 15 families (groups) of dogs living in the Chernobyl Exclusion Zone, an area now closed following the evacuation of the population living there following the nuclear disaster at Plant Number Four in April 1986.
Compared to purebred dogs and other populations living far from the crash site, the canine populations living there share genetic diversity with each other.
The findings were published this Friday in an article in the journal Science Advances (3). Researchers from the Polish Academy of Sciences, the Kiev National University and the State Ecocenter institute specializing in Chernobyl (Ukraine), Columbia University, North Carolina State University and the University of South Carolina (USA) and the National Institute for Human Genome Research, affiliated with the US National Institutes of Health (NIH).
To analyze dog populations, researchers collected blood samples from 302 people who were part of the Chernobyl Dog Research Initiative program between 2017 and 2019. This initiative aimed to welcome and provide veterinary care to dogs living freely in the isolated Chernobyl restricted area, reaching 800 people at one point.
Samples were collected in the vicinity of the plant (132 people), 28 near a nuclear fuel depot, nine in the ghost town of Pripyat, which was evacuated in 1986 after the nuclear disaster, 14 in the abandoned Semikhody railway station and another 81 circulating in the area. In addition, 154 dogs from the town of Chernobyl, about 15 km away, and another 16 from the town of Slavutych, 45 km away on the border with Belarus, were examined.
With the blood samples in hand, the researchers analyzed the collected genetic material. Because it wasn’t possible to know which genes — and if there was actually an effect — were being affected by continuous exposure to radioactivity, they looked for regions called SNPs, which are single nucleotides (a nucleotide is one of the bases of the DNA made up of the letters A, T, C, or G, which refer to the amino acids that make up each “letter” of genetic material). More than 129,000 nucleotide pairs were evaluated.
Research has shown that dogs from the vicinity of the power plant form a completely different group than individuals in the city of Chernobyl, which are likely descended from the pets left behind after the area was evacuated. In comparison to Eastern European dog breeds, it could be observed that the Chernobyl dogs formed a separate group, with differences in the geographic region of discovery occurring within the analysis itself.
“This is a ‘natural’ example of how natural selection works through isolation. The populations that remained in the plant’s exclusion zone are genetically different from those in the city of Chernobyl and in Eastern Europe,” explains Timothy Mousseau, professor of evolutionary biology at of the University of South Carolina and the last author of the study.
According to Gabriella Spatola, noting that the dogs there are distinct populations is the first step in understanding how these animals interact and exchange genetic diversity among themselves. “What the data shows us is that these dogs are even moving to other areas a little bit as we have seen genetic overlap, but in reality the isolation of this population was mainly due to finding shelter and food there and staying isolated. “
These dogs, the authors say, fed on food given by workers living in the area, or by cleaning up the facilities after the disaster, and more recently by tourists visiting the area in a form of “radioactive tourism.” visit. Many of them have been there for at least 15 generations.
“Now that we have been able to genetically identify these populations as distinct and they are whole family groups, we will proceed to the next phase of the experiment, which is to look for regions or signals in the DNA that indicate a modification are caused by radiation,” explains Spatola.
Some of the modifications can be a high mutation rate, deletions of entire parts of the genome, and even readaptations.
According to Elaine Ostrander, research into the effects of radiation on the canine genome can help answer questions such as new uses and drugs for cancer, changes in DNA in people who work near or with intense exposure to radiation, and even the effects of a longterm radiation exposure to our body.
“The next step will be to do the full sequencing of the genome and identify these signals. The applications to human health and even to understanding the effects of radiation are very promising. And this is the first study done on the genetic diversity of large mammals that have been exposed to radiation,” she says.
For Mousseau, the study will allow inferences to be drawn about other wildlife living there for which such a comprehensive analysis is not possible. “We know that the moose, horses and deer that live there can also be exposed to different levels of radioactivity. With dogs, in addition to largescale samples, we’ve been able to crosscheck comparisons with thousands of individuals from different breeds from around the world, and that’s fantastic.”