Dogs in Chernobyl are genetically different from others – 03/03/2023 – Science

One study found that dogs living close to the Chernobyl disaster area in Ukraine are genetically distinct from those further away 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 that live in the Chernobyl exclusion zone, an area now closed after the evacuation of the populations that lived there after the nuclear disaster that occurred at plant number four, in April 1986.

Compared to purebred dogs and other populations that live far from the crash area, the dog populations that live there share genetic diversity with each other.

The findings were published in an article in the specialized journal Science Advances this Friday (3). Researchers from the Polish Academy of Sciences, the National University of Kiev 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 individuals between 2017 and 2019 who were part of the Chernobyl Dog Research Initiative program. This initiative aimed to welcome and provide veterinary medical care to dogs that live loose in the isolated exclusion area of ​​Chernobyl and which, at a given moment, reached 800 individuals.

Samples were collected in the region of the plant (132 individuals), 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 train station of Semikhody and another 81 circulating in the area. In addition to these, 154 dogs from the city of Chernobyl, about 15 km from the incident, and another 16 from the city of Slavutych, on the border with Belarus, 45 km away, were also studied.

With the blood samples in hand, the researchers analyzed the collected genetic material. As it was not possible to know which genes —and whether there was, in fact, an effect— affected by continuous exposure to radioactivity, they looked for areas called SNPs, which are single nucleotides (a nucleotide is one of the bases of DNA, formed by the letters A, T , C or G, referring to the amino acids that make up each “letter” of the genetic material). More than 129 thousand pairs of nucleotides were evaluated.

Research has shown that dogs from the area close to the plant form a totally different group from individuals in the city of Chernobyl, probably originating from the pets left behind after the evacuation of the area. When compared to Eastern European dog breeds, it was possible to observe that the Chernobyl dogs formed a separate group, although within the analysis itself there was variation as to the geographic region in which they were found.

“This is an ‘in nature’ example of how natural selection acts through isolation. The populations that remained in the plant’s exclusion zone are genetically distinct from those in the city of Chernobyl and Eastern Europe”, explains Timothy Mousseau, professor of evolutionary biology at the University of South Carolina and the study’s last author.

According to Gabriella Spatola, identifying that the dogs there are distinct populations is the first step towards understanding how these animals are interacting and exchanging genetic diversity among themselves. “What the data shows us is that these dogs even move a little to other areas, as we saw genetic overlap, but in reality the isolation of that population was largely because they found shelter and food there and remained isolated. “

These dogs, according to the authors, lived on food given by workers who lived in the region or on cleaning the plants after the disaster and, more recently, on tourists who visit the area in a kind of “radioactive tourism”. Many of them have been there for at least 15 generations.

“Now that we have managed to genetically determine these populations as distinct, and they are groups of entire families, we are going to move on to the next stage of the experiment, which is to look for areas or signals in the DNA that indicate modification caused by radiation”, explains Spatola.

Some of the modifications can be a high rate of mutations, deletions of complete parts of the genome and even new adaptations.

According to Elaine Ostrander, research on the effects of radiation on the genome of dogs can help to elucidate issues such as new applications and drugs for cancer, changes that appear in DNA in people who work close to or with intense exposure to radiation and even the effects of long-term radiation exposure in our body.

“The next step will be to carry out the complete genome sequencing and identify these signals. The applications for human health and even for understanding the effects of radiation are very promising. And this is the first study carried out with the genetic diversity of large mammals. who were exposed to radiation,” she says.

For Mousseau, the study will make it possible to make inferences for other wild animals that live there and for which it is not possible to carry out such a comprehensive analysis. “We know that moose, horses and deer that live there can also be exposed to varying levels of radioactivity. In the case of dogs, in addition to large-scale samples, we were able to compare them with thousands of individuals of breeds from around the world, and that’s fantastic. .”