in 1986 In April, an explosion occurred at the Chernobyl nuclear power plant in the north of the then Ukrainian Soviet Socialist Republic, turning the surrounding region into the most radioactive zone on our planet. Nearly 40 years later, radiation levels remain high.
Humans have long ceased to live in the area, but recent research has found that animals living within a 30km radius of the plant in the so-called Chernobyl zone are physically and genetically different from their peers in other parts of the world – raising concerns about the effects of chronic radiation on their DNA. In a new study, researchers at New York University examined the microscopic worms that still live in the region – to see what effect Chernobyl radiation had on their genetic makeup.
“Chernobyl was a tragedy of unfathomable proportions, but we still do not fully understand the impact this disaster had on local life,” said lead author Sophia Tintori. “Has sudden environmental change resulted in the selection of species or even individuals of a species that are naturally more resistant to ionizing radiation?”
In order to answer this question, the scientist studied nematodes, small worms whose genomes (that is, all sets of the genetic material of an organism) are simple, and which reproduce quickly, which is why they are useful for understanding basic biological phenomena.
“These worms are ubiquitous and fast-living, allowing them to survive tens of generations of evolution — when a typical vertebrate is just ‘learning to tie its shoes,'” says study author Matthew Rockman.
Armed with Geiger counters and wearing personal protective equipment, the researchers collected hundreds of nematodes from locations throughout the exclusion zone that had been exposed to varying levels of radiation. The samples were then transported to New York University, frozen and later tested.
“We can cryopreserve the worms and then thaw them for research,” says Rockman. “This means we can stop evolution in the laboratory, which is not possible with most other animal models and is very valuable when we want to compare animals that have had different evolutionary histories.”
The researchers focused on a species of nematode called Oscheius tipulaeby sequencing 15 worms from Chernobyl and comparing them to five O. tipulae genomes from other locations. To the researchers’ surprise, they never found any radiation damage in the genomes of the Chernobyl worms.
“That doesn’t mean Chernobyl is safe – it’s more likely that nematodes are really resilient animals and can withstand extreme conditions,” Tintori says. “We also don’t know how long each of the worms we collected has been in the area, so we can’t be sure what level of impact each worm and its ancestors have experienced over the past four decades.”
What does this mean for us? The study’s findings provide insight into how DNA repair can vary between individuals, which may help to better understand the natural variation observed among humans.
“Now that we know which ones O. tipulae strains are more sensitive or tolerant to DNA damage, we can use these strains to study why different individuals are more exposed to carcinogens than others,” says S. Tintori. This could have implications for cancer research into why some people are genetically predisposed to the disease and others are not.
“Thinking about how individuals respond differently to DNA-damaging factors in the environment will help us better understand our own risk factors,” says lead study author Sophia Tintori.
The study is published in the journal PNAS.
Adapted from New Atlas.
