Axl Rose, Xotica, and Xavier, the Science Mill’s weirdly adorable axolotls, are scientific marvels.
While most salamanders develop lungs and grow up to become land dwellers, axolotls do things a bit differently. Axolotls exhibit a trait called neoteny, meaning they retain some juvenile characteristics throughout their entire lives. Because they never develop lungs, and instead keep their gills, axolotls are permanent under-water residents.
Even more amazing, axolotls can regenerate limbs and organs perfectly, without any scarring. They can do this as many times as necessary in as little as three weeks. Salamander’s Genome Guards Secrets of Limb Regrowth, an article by Elizabeth Preston for Quanta Magazine, explains why this regeneration is so impressive and important.
Salamanders are champions at regenerating lost body parts. A flatworm called a planarian can grow back its entire body from a speck of tissue, but it is a very small, simple creature. Zebra fish can regrow their tails throughout their lives. Humans, along with other mammals, can regenerate lost limb buds as embryos. As young children, we can regrow our fingertips; mice can still do this as adults. But salamanders stand out as the only vertebrates that can replace complex body parts that are lost at any age, which is why researchers seeking answers about regeneration have so often turned to them.
Humans and axolotls have more in common than you may think at first glance. No, we don’t have gills - much less gills on the outsides of our heads like wispy antennae - nor do we retain juvenile characteristics our entire lives. But as Preston writes, what we do share matters a lot to scientific research, especially now that labs have hurdled decoding the axolotl genome.
The main problem with the axolotl genome is that it’s enormous. It has 32 billion base pairs, making it about 10 times longer than the human genome. Despite that, axolotls and humans seem to have a similar number of genes, said Elly Tanaka, a biologist at the Research Institute of Molecular Pathology in Vienna