There are several species that are able to regenerate lost limbs, but the axolotl (Ambystoma mexicanum) is arguably the species that is best this regeneration. This little amphibian can not only regenerate lost limbs that it might lose in a battle, because he takes it one step further. An axolotl is actually capable of regrowing damaged organs! A study has shown that this include the ability to even regrow certain parts of its brain, a feature that has not been found in any other species.
An axolotl. Image by Wikimedia Commons user LoKiLeCh, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.
Since the axolotl has such unique abilities, it has been studied a lot by science, but it is also very popular to keep as a pet. It is considered critically endangered by the IUCN Red List, so maybe it’s a good thing that we have plenty of them in labs and aquariums all around the world. They are pretty common to find in pet stores, so just head over to one of these if you want to see how this guy looks like in real life.
Anyway, its ability to regenerate lost limbs and organs has made many scientists very interested in it, and they hope to uncover some secrets that could potentially teach us more about how this is done. The dream is of course to be able to replicate this feature to humans, but that is still far from possible with the technology we have today.
What exactly is an axolotl?
We have talked a bit about the axolotl’s ability to regenerate lost limbs and organs, but what exactly is this animal? For some reason people keep referring to it as a “walking fish” because of its limbs, but this is not true at all. It is in fact an amphibian, so the fact that it has legs instead of fins is not really surprising at all. If you want to see a fish with hands, check out the post I did about the Red Handfish a few days ago.
Unlike most other amphibians, the axolotl does not undergo metamorphosis from larvae to adulthood (like a frog does). What this means is that it never develop lungs, so even the adults have to stay aquatic in order to breath with heir gills.
In the wild you have to travel to Mexico to find them, and they are mostly found in small freshwater lakes close to Mexico City. Lake Xochimilco has wetlands around it, and these are typically where people go to look if they want to find one in the wild.
Cows grazing on some grass in the wetlands close to Lake Xochimilco. Image by Wikimedia Common user Jflo23, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.
The entire axolotl genome has been sequences
Scientists have just recently sequences the entire genome of the axolotl, and the findings have been published in Nature. While a “simple” genome sequestration might not seem like a big deal, the axolotl has a huge genome that has about ten times as many base pairs as the human genome, so it is a lot of work. It is currently the largest genome that has been sequences, so in many ways this is a feat by itself.
An axolotl at the Steinhart Aquarium in San Francisco. Image by Stan Shebs, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.
The paper has some interesting remarks, but they did of course not find the “secret” to regenerating lost limbs and organs by simply looking at the genome. It is of course mixed in there somewhere, but decoding the DNA from a long string of T, C, A and Gs is a lot of work!
It was previously known that the Prod1 gene has been contributing to the regeneration of lost limbs, but this new paper also identified other parts of the same gene family to be part of the function. The scientists have also found several other interesting regions of the DNA that they believe to be playing a part in the regeneration, so hopefully someone will be able to take a closer look at these parts in the future.
While the genome has been sequences, unlocking the information from it has only begun, and it will be very exciting to see if more papers are published about how it can regenerate limbs and organs. There are also other organisms who can do these types of regenerations (but rarely vertebrates), so one possible way forward is to compare the genomes of these organisms with each other to find parts that are the same.
Thanks for reading
Thanks for reading about the genome sequence of the axolotl! I hope you liked it, and make sure to leave a comment below if you got anything to share. If you want to learn more then follow the links in the post, but be warned, papers about genetics is almost unreadable by those who are not familiar with it.
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