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American alligators are about as close to dinosaurs as you can get in modern times and can grow up to 14 feet in length. While much smaller reptiles such as lizards are able to regenerate their tails, the question of whether the much larger alligator is able to repel their massive tails has not been well studied. A team of researchers from Arizona State University and the Louisiana Department of Wildlife and Fisheries have found that young alligators have the ability to regrow their tails up to three-quarters of a foot, or 18% of their total body length.
An interdisciplinary team of scientists used advanced imaging techniques combined with proven methods of studying the anatomy and organization of tissues to examine the structure of these regrown tails. They discovered that these new tails were complex structures with a central skeleton made up of cartilage surrounded by connective tissue interwoven with blood vessels and nerves. They speculate that the regrowth of their tails gives alligators a functional advantage in their murky aquatic habitats.
The results are published in the journal Scientific reports.
“What makes the alligator interesting, apart from its size, is that the regrown tail shows signs of regeneration and wound healing within the same structure,” said Cindy Xu, recent PhD student in the program. ASU molecular and cellular biology and lead author of the paper. “The regrowth of cartilage, blood vessels, nerves and scales was consistent with previous lizard tail regeneration studies in our lab and others. However, we were surprised to find scar-like connective tissue in place of skeletal muscle in the repelled alligator tail. Future comparative studies will be important to understand why regenerative capacity is variable among different groups of reptiles and animals. “
“The spectrum of regenerative capacity across species is fascinating, it is clear that there is a high cost to produce new muscle,” said Jeanne Wilson-Rawls, co-lead author and associate professor at the School. of Life Sciences from ASU. “
“Staff biologists in our Alligator Research and Management Program have been pleased to partner with Dr Kusumi of Arizona State University for many years,” said Ruth M. Elsey, Biologist in charge of the Department of Louisiana wildlife and fisheries. “We are seeing alligators in the field with indications of possible tail tissue regrowth, but their expertise has led to the current study detailing the histological changes associated with the ability of partial tail regrowth or scarring.”
Alligators, lizards, and humans all belong to a group of bone-frame animals called amniotes. While the interdisciplinary team has previously studied the ability of lizards to regenerate their tails, this discovery of the regrowth of complex new tails in the alligator provides additional insight into the process in amniotes.
“The ancestors of alligators, dinosaurs and birds went their separate ways around 250 million years ago,” said co-lead author Kenro Kusumi, professor and director of ASU’s School of Life Sciences and dean. associated with the College of Liberal Arts and Sciences. “Our discovery that alligators have retained the cellular machinery to regrow complex tails while birds have lost this ability raises the question of when in evolution this ability was lost. Are there any fossils of dinosaurs, the lineage of which has led to modern birds, with repelled tails “We have not found any evidence of this so far in the published literature.”
“If we understand how different animals are able to repair and regenerate tissue, this knowledge can then be harnessed to develop medical therapies,” said Rebecca Fisher, co-author and professor at the University of Arizona College of Medicine-Phoenix and the ASU School. Life sciences. The researchers hope their findings will lead to the discovery of new therapeutic approaches to repair injuries and treat conditions like arthritis.
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The research team included Kusumi, Xu, Wilson-Rawls and Alan Rawls from the ASU School of Life Sciences, Ruth Elsey from the Louisiana Department of Wildlife and Fisheries and Fisher from the College of Medicine of the ‘University of Arizona at Phoenix. This research was funded with support from the College of Liberal Arts and Sciences at ASU.
The ASU School of Life Sciences is an academic unit of the College of Liberal Arts and Sciences.
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