The axolotl (water monster) is one of my favourite animals. Despite what expert, ‘Linda Adkins’ says in her book, ‘Keeping Axolotls’, it is not a reptile. They are in a genus of 32 salamanders; salamanders are newts, (Caudata) which are amphibians, along with frogs and toads (Anura) and the wider caecilians (Gymnophiona). Other orders existed in the past.
It’s from freshwater lakes and caves in Mexico and considered critically endangered on the IUCN register, but they are very popular as pets (and in labs). I can only imagine that there are captive breeding programmes, which enables the laws of the world to allow them to be pets, given their rare status.
Axolotls exhibit neoteny , meaning that they reach sexual maturity without undergoing metamorphosis. Many species within the axolotl's genus are either entirely neotenic or have neotenic populations. In the axolotl, metamorphic failure is caused by a lack of thyroid stimulsating hormone, which is used to induce the thyroid to produce thyroxine in transforming salamanders. The genes responsible for neoteny in laboratory animals may have been identified; however, they are not linked in wild populations, suggesting artificial selection is the cause of complete neoteny in laboratory and pet axolotls.
Thyroid hormone contains a lot of iodine, which is taken from the food chain. In the wild, where iodine is scarce (like high mountain lakes), transformation won’t take place and more extreme shortages leads to cretinism and dwarfism, as it does in humans. Pet Axolotls are largely chosen for their looks and their entirely aquatic existence in their juvenile state.
Another amazing thing about Axolotls, is their ability to regenerate. Humans can regenerate. Surgical leg extensions or amputated limbs can increase a little, e.g. the skin regenerates and covers gaps. Reptiles do it a lot better, despite significant scaring, and many inverts can do it. Spiders and some lizards and salamanders can release limbs, ‘at will’ when needed and regenerate them. This is called autotomy. Some inverts can regenerate entirely, even if cut into pieces with each part regenerating to a new organism. Axolotls though are special, because they are vertebrates, and this interests science and medicine greatly.
Axolotls rarely leave scaring when regenerating and can even regenerate extra/additional limbs (as well as regenerated replacements). Regeneration is not limited to external body parts, but organs too. Even parts of the brain, heart and spinal column. Not only this, but they transplant really well too. Eyes, limbs or even an additional head (from another specimen) can be used and function. All tissue, muscle, nerves, blood vessels, cartilage, bone, spine etc. can be regenerated and host/donor organs even welcomed. If the limb (or even partial limb) from a standard specimen is transplanted to an albino specimen, the specimen will use the limb’s own genetics, so it will have, and grow and work simultaneously with the normal (non-albino) limb.
After amputation, the cells at the damage site (be they blood or skin cells or whatever) transform into stem-like cells to regenerate the whole limb/site. This is one reason there is no scaring, unlike other animals, and there is obviously great potential for burn or scar or disfigurement skin graft work in other animals like humans. Axolotls are also 100 x more resistant to cancer than any other animal.
By genetically adding bio-luminescent proteins (like exhibited in jellyfish), it is possible to add them to cancer cells to watch its spread/development through the body.
The genome of the Axolotl has only recently (2018) been fully sequenced and it is the largest in the animal kingdom so far, with 32 billion base pairs, and there are a lot of similarities to us, which is really exciting to know.
And a final piece of trivia. About 7 months ago in London, at the Tetrapod Zoological Conference, hosted by Darren Naish, there was an open quiz, which went down to a tie break. The final question was to see who could state, more accurately, the number of base pairs in an Axolotl. And the winner was… Alberta Nikus – our very own, who is an advisor, consultant, data entry scientist and PhD candidate, who was also a guest speaker at TetZooCon. Yes, we had two, with Aron Ra being the other, presenting the Project. So, we had two speakers from the Project!
I’d love Albert to do a guest blog here or similar on his specialist area of Pterosaurs/birds (or anything he likes). He did a great presentation at Tetzoocon and it was such a pleasure to meet such a nice guy. I also have other people in mind for a blog. Watch this space.