Worms at Chernobyl resistant to mutation.

The article here https://phys.org/news/2024-03-tiny-worms-tolerate-chornobyl.html

I do think the article is put together particularly well.

The worms do not show new mutations compared to genomic analogues elsewhere in the field.

They have endured however despite high levels of ionising radiation from 1986 following the disaster.

The paper just has the abstract so does not show the discussion or conclusion.

 

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Just to give some context, there are frog species at Chernobyl that have mutated from bright green to black. The melanin gives protection from radiation so the darker colour frogs had an advantage. Darker coloured frogs mated with other darker coloured frogs and 38 years later we only have black frogs.

The Manchester moth is useful comparison, although the Evolutionary pressure was pollution from the industrial revolution not radiation.

 

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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?

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?

 

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How does melanin protect from radiation? I thought it worked by absorbing UV photons before they can cause damage. If that's so, it is not clear to me why it should protect from α, β or γ radiation.

Or does melanin also act as a radical scavenger?

 

Yeah it's a flat out contradiction, the study says no evidence of mutations from radiation BUT shows no resistance but the researcher says they show high levels of resistance to hostile environment.
I will send them a communication.

 

In humans melanin gives protection from UV but I do not know the mechanism.
I will pull up the frog paper.

 

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.

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.​

 

Here is the frog article,

https://phys.org/news/2022-09-chernobyl-black-frogs-reveal-evolution.html

The article mentions protection from ionising radiation, Oxygen species and cites a study on fungi.

"Melanin is responsible for the dark color of many organisms. What is less known is that this class of pigments can also reduce the negative effects of ultraviolet radiation. And its protective role can extend to ionizing radiation too, as it has been shown with fungi. Melanin absorbs and dissipates part of the radiation energy. In addition, it can scavenge and neutralize ionized molecules inside the cell, such as reactive oxygen species."

 

I meant to put "NOT" particularly well written but I can't edit it now.

 

Ok I can see from the structure it could be a radical scavenger, like other highly conjugated molecules. “Absorbs and dissipates part of the radiation energy” sounds like hand-waving, however. Unless they are talking there about attenuating UV by absorption of some of it.

 

There are contradictory statements in the article.
One being a direct quote from one of the researchers.
Only the abstract available so we cannot see the discussion.
I will ping a mail off to the site.

 

I believe this phenomenon of UV resistance is also present in dark-skinned humans.

The Protective Role of Melanin Against UV Damage in Human Skin

more.... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/#

and because mitosis is indicated, a related article :
Melanin Distribution in Human Skin: Influence of Cytoskeletal, Polarity, and Centrosome-Related Machinery of Stratum basale Keratinocytes
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003549/

 

Yes this is well documented. Can you please stick to the contents in the article?

This is hard science.

 

Hahaha, fat chance.

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But did you ever get anywhere with the enquiries you were going to make about the inconsistencies in that article?

 

Another site acknowledged the same issue. I will contact them, I did not get around to it.

 

No, "this" is not hard science.
This is a discussion forum on the hard science of radiation resistance in worms specifically, rather than a discussion on native or acquired radiation resistance in general.
Would you agree?

 

By "hard" science I meant there is a paper.

https://www.pnas.org/doi/abs/10.1073/pnas.2314793121

 

Thanks for the link

 

I think you can only get the abstract unfortunately.
I am writing to phys org regarding the article which is misleading.

 

This is really interesting stuff. Looking forward to results of your inquiry.