The American alligator’s tail can regenerate like that of other reptiles
Some lizards have developed strategies to regrow their docked tails, but until now little was known about the much larger American alligator’s ability to regenerate it. A team of scientists has discovered that the youngest alligators can recover part of this limb, but this differs from the original structure.
The case of the lizards, with their “removable” tails, is well known. These small vertebrates are capable of re-creating nerve cells, like other lizards, and regenerating this limb. The strategy of shedding the tail is common to escape predators, but what about much larger reptiles, such as the American alligator?
So far, it was not well documented if this crocodilian, one of the largest in the American continent, could have this ability to recover its enormous tail. A team from Arizona State University and the Louisiana Department of Wildlife and Fisheries, both in the United States, shows for the first time that the youngest specimens, caught in the wild, had recovered their tail up to 18% of the full length of their body, although they were morphologically different from the original sections.
To analyze the structure of the regenerated limbs, the scientists performed MRIs and X-rays combined with anatomical and tissue organization studies. The results, published in the journal Scientific Reports, showed that the new tails lacked skeletal muscle – unlike other lizards – and formed complex structures with a central skeleton composed of cartilage and surrounded by fibrous connective tissue intertwined with blood vessels and nerves.
“What makes the alligator interesting, apart from its size, is that the re-growing tail shows signs of regeneration and wound healing within the same structure,” explains Cindy Xu, lead author and researcher at the American university.
This overproduction of connective tissue was similar to wound healing or fibrosis in mammals, the scientists found. “We were surprised to discover scar-like connective tissue rather than skeletal muscle in the regenerated crocodile tail,” Xu adds.
The partial limb growth of these crocodiles does share similarities with the regenerated tails of New Zalanda tuataras and the regenerated limbs of adult Xenopus frogs, which have a cartilaginous endoskeleton surrounded by connective tissue without skeletal muscle.
What does regeneration contribute?
The study confirms that between the different species of reptiles and other animals, the regenerative capacity varies, and can be costly. In the case of American alligators (Alligator mississippiensis), scientists believe that regenerating their tails can give them a functional advantage when living in murky aquatic habitats.
This finding provides more information on how reptiles are the only amniotes – a group of animals with backbones among which humans are found – to maintain the ability to recover their lost limbs. “The ancestors of alligators, dinosaurs and birds separated about 250 million years ago. The study shows that the alligators have retained the cellular machinery to regenerate complex tails while the birds have lost that capacity ”, emphasizes Kenro Kusumi, co-principal author, and professor and director of the School of Life Sciences of the University of the State of Arizona . So at what point in evolution was this ability lost? So far, scientists have found no evidence of fossils of dinosaurs, whose lineage led to modern birds, with regenerated tails.
Furthermore, understanding how different animals can regenerate tissues could help develop medical therapies, according to the researchers. The team hopes that these findings will uncover new therapeutic approaches to repair injuries and treat diseases such as arthritis
Some lizards have developed strategies to regrow their docked tails, but until now little was known about the much larger American alligator’s ability to regenerate it. A team of scientists has discovered that the youngest alligators can recover part of this limb, but this differs from the original structure. The case of the lizards, with […]
The American alligator’s tail can regenerate like that of other reptiles — Awesome Facts to learn on Virtual Science
DNA profiling, a technique where investigators compare the base pair order of DNA found at the crime scene to a suspect’s DNA. Now, another type of genetic analysis – DNA barcoding – is being used to combat illegal wildlife trading.
An example is the 2003 case against Joao Migel Folgosa. Mr. Folgosa was apprehended at the Recife Internal Airport of Brazil when police discovered him hiding 58 eggs under his shirt. Based on egg morphology – and Mr. Folgosa history as an exotic pet trafficker – officials suspected that the eggs were parrot. However, they were unable to specify the species. Because Brazil has 21 endangered parrot species but 83 species overall only limited charges could be brought against him. The case was further weakened by Mr. Folgosa claim that the eggs were from quails.
Twelve years later Dr. Miyaki and colleagues picked up this cold case. They retrieved tissue samples from the 58 eggs/embryos and isolated DNA from each. Then, using a combination of primers, they amplified and sequenced the DNA at two locations in the mitochondrial genome. Finally, they compared their results to publically available records in BOLD (Barcode of Life Data System) and Genbank. Through this process they were able to positively identify 57 of the eggs. All 57 were parrot eggs. More specifically fifty belonged to Alipiopsitta Xanthops (a IUCN vulnerable species), three belonged to Ara ararauna, and four were either Amazona aestiaval or Amazona ochrocephala.
