There seems to be a disconnect in this write-up, unless I have misunderstood. They say there is no evidence that these nematodes have evolved a higher degree of radiation resistance, but then say their research sheds light on what makes different strains of nematode more or less resistant to DNA damage.
But how, if there was no evidence of any difference between the Chernobyl population and others?
Note that I'm trying to sort this out for myself as much as providing what
might be the specific relevant passages pertaining to the issue.
"In recent years, researchers have found that some animals living in the Chernobyl Exclusion Zone—the region in northern Ukraine within an 18.6-mile radius of the power plant—are physically and genetically different from their counterparts elsewhere, raising questions about the impact of chronic radiation on DNA. [...] Worms were collected from locations throughout the zone with different amounts of radiation."
We can, of course, discount that initial reference to "counterparts elsewhere" (outside Chernobyl) due to it concerning other animals -- not the nematodes collected for this investigation. But there is a second spot that might be guilty of ambiguity.
The phrase below of "
worms from Chernobyl are not necessarily more tolerant of radiation" would seem conflicting, unless this is indeed referring to nematodes outside Chernobyl, rather than those within. Since it had just stated that the Chernobyl worms themselves "
were different from each other in how well they tolerated DNA damage".
[...] The researchers were surprised to find that using several different analyses, they could not detect a signature of radiation damage on the genomes of the worms from Chernobyl. ... While the lineages of worms were different from each other in how well they tolerated DNA damage, these differences didn't correspond to the levels of radiation at each collection site. Their findings suggest that worms from Chernobyl are not necessarily more tolerant of radiation and the radioactive landscape has not forced them to evolve.
The researchers, I assume, believe that the tolerance as well as those variations among them are within the range of their normal genetic heritage, rather than the result of radiation caused mutations. And apparently would not be above what nematodes beyond Chernobyl could tolerate as well.
Or are they saying that although they got a null result from their fieldwork at Chernobyl, the work they subsequently did, using artificial irradiation of nematodes in the lab, has shown up some differences?
And this is where I'm apparently missing some additional paper or article with respect to the "
using artificial irradiation of nematodes in the lab". Or is my confusion due to not having total access to the paper provided (being limited to the abstract)?
[...] The results give researchers clues into how DNA repair can vary from individual to individual—and despite the genetic simplicity of O. tipulae, could lead to a better understanding of natural variation in humans.
"Now that we know which strains of O. tipulae are more sensitive or more tolerant to DNA damage, we can use these strains to study why different individuals are more likely than others to suffer the effects of carcinogens," said Tintori.
How different individuals in a species respond to DNA damage is top of mind for cancer researchers seeking to understand why some humans with a genetic predisposition to cancer develop the disease, while others do not.
