By: Aloyzeus Reotutar
Lizards are renowned for their regenerative ability to grow tails as needed, but the new tail is often far from ideal.
When certain species of lizard find themselves in life-threatening situations, they can shed their own tail and then grow a new one over the course of several weeks or months. However, the new tail is far from a perfect replica – it is supported by a solid cartilaginous tube rather than a spine containing bones and nerves.
However, in a new study, scientists have found a way to allow the lizards to regenerate their tails much closer to the originals. The technical term for this process is dorsoventral patterning, where the dorsal or superior side is composed of skeletal and neural tissue and the inferior or ventral side is cartilage.
For some reason, regrown tails are most often completely “ventralized”, that is, only cartilage grows. To figure out what’s going on, the team analyzed and compared how lizards’ tails are formed during embryonic development and during adult regeneration.
In both cases, the entire process is performed by neural stem cells (NSCs), and the team has identified the molecular signal they produce by ventralizing the tissue. Embryonic NSCs reproduce this signal only on the underside of the tail, whereas adult NSCs do this from above and below, creating a cartilaginous tube.
The team tried several ways to stop the process of ventralizing the regenerated tails. The scientists wanted to block the signal in adult NSCs, but the new neural tissue in the upper part of the tail never recovered. They tried to implant embryonic NSCs into the tail stump of adults, but they still responded to the ventralization signal.
Therefore, the researchers used the CRISPR method to edit embryonic NSCs so that they no longer respond to this signal. Then they were implanted into the tail stumps of adult lizards – as a result, they regenerated “perfect” tails with bones and nerves on the upper side. For now, the results are only good news for lizards, but the find may ultimately serve as the basis for research that could lead to advances in human regenerative medicine.
Lozito, T.P., Londono, R., Sun, A.X. et al. Introducing dorsoventral patterning in adult regenerating lizard
tails with gene-edited embryonic neural stem cells. Nat Commun 12, 6010 (2021).
IMAGE: The Mourning gecko (Lepidodactylus lugubris) was the subject of the new study into