Extraordinary Salamander Can Grow New Limbs and Has Longest Genome Ever Sequenced

A creature that can regenerate lost body parts is strangely reminiscent of a Spider-Man backstory, but this week scientists published new findings about just such an animal.

The axolotl is a bizarre, aquatic amphibian that breathes water and lives in Mexico, and is most notable for its comic book–like super power: It can heal grave wounds and even regrow lost limbs. If it loses a leg or an eye, or even severs its spine, it can regrow a new one.

Now, in an effort to understand how the axolotl does this, scientists have sequenced its entire genome, publishing the research Wednesday in the journal Nature.

Biologists found that the axolotl has an exceptionally long genome, with 32 billion base pairs of DNA, 10 times the number a human has. It’s the largest genome ever sequenced.

Albino_Axolotl A rare albino axolotl crawls inside an aquarium at Aquaria KLCC in Kuala Lumpur, Malaysia. REUTERS/David Loh

The scientists had hoped to discover the special quality of the axolotl's genome that allows the amphibian to sprout new limbs, which could be applied to humans who have lost their limbs. But the sequencing of the genome didn’t uncover the answer—yet.

"We now have the map in our hands to investigate how complicated structures such as legs can be re-grown," Sergej Nowoshilow, one of the authors, told New Atlas. "This is a turning point for the community of scientists working with axolotl, a real milestone in a research adventure that started more than 150 years ago."

Notably, five of the sequenced genes are specifically active on the stumps of the axolotl's regenerating limbs, offering science another clue to how it works. They also found 93 gene sequences that don’t exist in amniotes—mammals, birds and reptiles—information that could be integral to limb regeneration as well.

Oddly, despite the extreme length of the genome, the researchers found that the animal is missing one gene they thought was vital to all life, the PAX3. Another similar gene called the PAX7, however, took over the critical functions of the missing one.

The researchers' next step is to further study the axolotl and its genome to find the source of its regenerative ability, which could potentially lead to better wound healing treatment for humans.