DNA to RNA to Editing to Protein

As I looked into what makes a species a species last week I assumed that of course, DNA had to be a factor in what makes us who we are. Over time this has changed and it is these changes over a long period of time that allow us to develop into creatures more adapt to our environment. It should take animal generations to adapt to a new environment but maybe one can do it in a shorter amount of time. I go back to one of my first posts which spoke of the commonly known trend of DNA to RNA to protein. We change our DNA so that we can have traits produced to survive in our environments, but why not edit RNA to create the desired proteins.

There is information that squids, octopuses, and other coleoids are able to use post-transcription processes to edit their DNA on a different level than mammals. From what I remember we splice out our introns to leave our exons when making our mature RNA. The article states even though we have sites for recoding humans generally try to avoid this. We are usually born as functioning human beings and altering that can lead to dangerous effects. We can see when comparing ourselves to mice that we share about only 36 recording sites. When comparing the coleoids we see a much higher comparison which could reach the tens of thousands depending on the relatedness of species.

Looking at the evidence the recoding is not a mistake, but finding what it means is another problem. There is mention of ADAR enzyme which plays a part in editing. This is able to change an RNA adenosine to inosines. These inosines also have a structure which allows it to act like guanosine and pair to cytidine. This It is stated that the editing is usually in the nervous cells of the coleoids. I am not sure if this has an effect on their intelligence which many can consider is higher than most other animals out there. It seems, many zoos I hear that these are intelligent animals and I have seen videos showing their ability to problem solve by getting out of jars while inside of one.

Moving on from their intelligence and back to editing, being able to use this ADAR enzyme to make a larger variety of proteins can provide many benefits. For example, it is found when comparing two sets of species which live in different temperature waters, 0 and 30 degrees Celsius, we find that the even though these have nearly identical genes the mRNAs had multiple editing sites which lead to different effects in survivability. It was stated an isoleucine to valine change in the structure destabilized the potassium channels leading to quicker firing rates in action potential. The process is temperature sensitive and this adaption allows the Antarctic octopuses to survive in the cold.

It is here we can ask whether this is more a long-term effect of evolution or an adaption within a shorter span of time. And how would it affect evolution in the future? If it is possible to adapt within a lifetime then a change in DNA which could account for higher survivability may not be as advantageous as the system already in place. I wonder if this would slow down the evolutionary changes which could occur or have any effect at all. I would think it would lessen it if it was as simple as only certain traits being advantageous, but other factors come into play. The environment could change due to natural events, pray or food sources can become scarce, and more. It also states many of the recoding sites themselves require preservation so mutations would be reduced to positions in the proximity of these sites.

As research goes further it would be interesting to see what the limits of this editing are and how it can be advantageous to us if we can take advantage of how it works. Since there is an association with the recoding sequences and the nervous system I wonder how valuable it is for them as far as learning is concerned, and possibly if this could assist us with our own neurological disorders if more information is found. In the back of my mind, it makes me wonder what living animals might have the ability to take over if humans became extinct.

Sources:

Trade-off between Transcriptome Plasticity and Genome Evolution in Cephalopods
Noa Liscovitch-Brauer, Shahar Alon, Hagit T. Porath, Boaz Elstein

Functions and Regulation of RNA Editing by ADAR Deaminases Kazuko Nishikura

A Role for A-to-I RNA Editing in Temperature Adaptation
Sandra C. Garrett and Joshua J. C. Rosenthal

'Smart' cephalopods trade off genome evolution for prolific RNA editing
https://www.sciencedaily.com/releases/2017/04/170406121601.htm