Hi

I was reading an article on Science Daily about the discovery of a Lichen in the Mojave Desert, USA. This lichen has developed the ability to resist UVC radiation via a pigment.

This got me thinking that I think most things biological can be traced back to genetics, so perhaps there is a genetic change that has taken place so this pigment develops. (probably not quite the right terminology there). in which case could it be possible to map the GENOME and indentify any dna / genes that are responsible for the pigment, then use CRISPR to spice these in to perhaps a plant that we can make polymers from (and make the polymer UVC resistant, or perhaps even some foods, so that these plants can be grown either on space vehicles or perhaps on the Moon or later Mars.

Just asking as I am not sure if this sort of thing is possible

Thanks

Paul

Reference

ScienceDaily

Mojave lichen defies death rays—could life thrive on dist...

Lichen from the Mojave Desert has stunned scientists by surviving months of lethal UVC radiation, suggesting life could exist on distant planets orbiting volatile stars. The secret? A microscopic “...

Edited August 7Aug 7 by paulsutton

It would be interesting to know how it evolved uvc resistance because afaik uvc doesn't reach the ground because it is too energetic and reacts with oxygen to form ozone high up in the atmosphere.

Edited August 7Aug 7 by StringJunky

3 minutes ago, StringJunky said:

It would be interesting to know how it evolved uvc resistance because afaik uvc doesn't reach the ground because it is too energetic and reacts with oxygen to form ozone high up in the atmosphere.

As I understand the paper, here: https://www.liebertpub.com/doi/10.1089/ast.2024.0137. from which the Science Daily bulletin is taken, the UV screening pigment syctonemin: https://en.wikipedia.org/wiki/Scytonemin. is also found in desert cyanobacteria. It seems to be hypothesised that it may have evolved very early in the Archaean, before the Great Oxygenation Event, when there would have been a reducing atmosphere with no free oxygen - and presumably therefore no protective ozone layer.

However I notice the paper also says that at that time reduced iron (I suppose they mean Fe²⁺ as opposed to Fe³⁺) would have been present at quite high concentrations in seawater, i.e. before it oxidised and precipitated out into the rusty red rocks generated when free oxygen appeared. The paper suggests this dissolved iron may have played a role in absorbing UVC and helped screen organisms from it. Which rather seems to militate against the need for a sunscreen pigment like syctonemin against UVC. But then they say when the Great OxygenationEvent took place the shielding iron would have gone, leading to an advantage in having a UV screening pigment to hand - and also an antioxidant since avoiding oxidation then became a further challenge for organisms.

I suspect the answer may be that syctonemin gives broad spectrum protection from UV, not just against UVC. It may be protection from UVB and A that was the issue when its synthesis evolved. In other words it is just a matter of luck, as it were, that it happens to protect against UVC as well - which is what these exobiologists were interested in, as they were looking at life outside the Earth in harsher environments.

But I may have misconstrued this so would welcome other commentary.

1 hour ago, exchemist said:

As I understand the paper, here: https://www.liebertpub.com/doi/10.1089/ast.2024.0137. from which the Science Daily bulletin is taken, the UV screening pigment syctonemin: https://en.wikipedia.org/wiki/Scytonemin. is also found in desert cyanobacteria. It seems to be hypothesised that it may have evolved very early in the Archaean, before the Great Oxygenation Event, when there would have been a reducing atmosphere with no free oxygen - and presumably therefore no protective ozone layer.

However I notice the paper also says that at that time reduced iron (I suppose they mean Fe²⁺ as opposed to Fe³⁺) would have been present at quite high concentrations in seawater, i.e. before it oxidised and precipitated out into the rusty red rocks generated when free oxygen appeared. The paper suggests this dissolved iron may have played a role in absorbing UVC and helped screen organisms from it. Which rather seems to militate against the need for a sunscreen pigment like syctonemin against UVC. But then they say when the Great OxygenationEvent took place the shielding iron would have gone, leading to an advantage in having a UV screening pigment to hand - and also an antioxidant since avoiding oxidation then became a further challenge for organisms.

I suspect the answer may be that syctonemin gives broad spectrum protection from UV, not just against UVC. It may be protection from UVB and A that was the issue when its synthesis evolved. In other words it is just a matter of luck, as it were, that it happens to protect against UVC as well - which is what these exobiologists were interested in, as they were looking at life outside the Earth in harsher environments.

But I may have misconstrued this so would welcome other commentary.

Sounds good to me. My error, in hindsight, is not going back far enough when conditions were different.

Edited August 7Aug 7 by StringJunky

1 hour ago, exchemist said:

I suspect the answer may be that syctonemin gives broad spectrum protection from UV, not just against UVC. It may be protection from UVB and A that was the issue when its synthesis evolved. In other words it is just a matter of luck, as it were, that it happens to protect against UVC as well

My first thought was that the UVC protection was a spandrel. (For those unfamiliar, Gould and Lewontin used the analogy of a spandrel (a structural feature in ancient churches etc) to describe traits in organisms that are byproducts of the evolution of other characteristics, rather than direct products of natural selection and adaptation. )

Thanks for the replies, certainly seems an interesting discovery and important for finding life on other planets and maybe how life developed here on Earth. If we factor this sort of discovery in, we may have to redefine what we mean by habitable or habitable zone in terms of radiation exposure.

I found this paper: https://webstatic.niwa.co.nz/library/rs365(1856)p1889.pdf

which suggests that life could actually have been able to colonise both the land and the oceans in the presence of the UVC flux that would have reached the surface before there was a screening ozone layer. Iron once again features as one of several potential screening agents. Though it seems to be Fe(III) rather than Fe(II) they considered this time.