“Axolotls are legendary for regenerating limbs and parts of the central nervous system,” says study co-author Maximina H. Yun, a biologist at the Chinese Institutes for Medical Research in Beijing.

Here it is, floating silently in the green light of its microwave-sized tank: the axolotl — the googly-eye Mexican salamander known for its ability to regenerate lost body parts. The creature, with ...