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Researchers discover regenerated lizard tails are different from originals

October 8, 2012

Just because a lizard can grow back its tail, doesn’t mean it will be exactly the same. A multidisciplinary team of scientists from Arizona State University and the University of Arizona examined the anatomical and microscopic makeup of regenerated lizard tails and discovered that the new tails are quite different from the original ones.

The findings are published in a pair of articles featured in a special October edition of the journal The Anatomical Record. Researchers discover that regenerated lizard tails are different from originals Download Full Image

“The regenerated lizard tail is not a perfect replica,” said Rebecca Fisher, an associate professor in ASU’s School of Life Sciences, and at the UA College of Medicine – Phoenix. “There are key anatomical differences including the presence of a cartilaginous rod and elongated muscle fibers spanning the length of the regenerated tail.”

Researchers studied the regenerated tails of the green anole lizard (Anolis carolinensis), which can lose its tail when caught by a predator and then grow it back. The new tail had a single, long tube of cartilage rather than vertebrae, as in the original. Also, long muscles span the length of the regenerated tail compared to shorter muscle fibers found in the original.

"These differences suggest that the regenerated tail is less flexible, as neither the cartilage tube nor the long muscle fibers would be capable of the fine movements of the original tail, with its interlocking vertebrae and short muscle fibers," Fisher said. "The regrown tail is not simply a copy of the original, but instead is a replacement that restores some function."

While the green anole lizard’s regenerated tail is different from the original, the fact that lizards, unlike humans, can regenerate a hyaline cartilage skeleton and make brand new muscle is of continued interest to scientists who believe learning more about regeneration could be beneficial to humans in the future.

"Using next-generation technologies, we are close to unlocking the mystery of what genes are needed to regrow the lizard tail,” said Kenro Kusumi, an associate professor in School of Life Sciences in the College of Liberal Arts and Sciences, and co-author of the papers. “By supercharging these genes in human cells, it may be possible to regrow new muscle or spinal cord in the future."

“What is exciting about the morphology and histology data is that these studies lay the groundwork for understanding how new cartilage and muscle are elaborated by lizards,” said Jeanne Wilson-Rawls, co-author and associate professor in the School of Life Sciences. “The next step is understanding the molecular and cellular basis of this regeneration.”

Another interesting finding is the presence of pores in the regenerated cartilage tube. While the backbone of the original lizard tail is made of many bones with regular gaps, allowing blood vessels and nerves to pass through, in the regenerated tail, only blood vessels pass through the cartilage tube pores. This observation suggests that nerves from the original tail stump grow into the regenerated tail.

The researchers hope their findings will help lead to discoveries of new therapeutic approaches to spinal cord injuries and diseases such as arthritis.

The research team included Jeanne Wilson-Rawls, Kenro Kusumi, Alan Rawls, and Dale DeNardo from ASU’s School of Life Sciences and Rebecca Fisher from School of Life Sciences and University of Arizona College of Medicine-Phoenix.

This research was funded by Arizona Biomedical Research Commission, grant #1113, and National Center for Research Resources and the Office of Research Infrastructure Programs (ORIP) of the National Institutes of Health, grant #R21 RR031305.

Sandy Leander,
School of Life Sciences
Al Bravo
UA College of Medicine-Phoenix


Sandra Leander

Manager, Media Relations and Marketing, School of Life Sciences


Gluten-free craze not backed by science, ASU professor finds

October 8, 2012

There is no benefit for the average healthy adult to follow a gluten-free diet, according to research published by an Arizona State University professor in the September 2012 issue of the Journal of the Academy of Nutrition and Dietetics. The study debunks the idea that going gluten-free is an effective way to lose weight.

Glenn Gaesser, professor and director of the Healthy Lifestyles Research Center in the ASU School of Nutrition and Health Promotion, notes that while gluten-free dieting has gained considerable popularity, there is no published evidence to support such claims. In fact, there are data to suggest that gluten itself may provide some health benefits. Download Full Image

Gaesser wrote “Gluten-free diet: imprudent dietary advice for the general population?” with Siddhartha Angadi, an ASU doctoral student who graduated in May and now is a postdoctoral scholar at the University of California, Los Angeles, School of Nursing.

Gluten refers to protein found in the grains wheat, rye and barley. People who have celiac disease and gluten sensitivity must avoid all foods containing gluten to avoid abdominal cramping, bloating and diarrhea. About one percent of Americans have celiac disease and another six percent suffer from gluten sensitivity, yet many people believe going gluten-free leads to good health for everyone.

“The market for gluten-free products is expected to reach $2.6 billion in 2012, and it’s an industry based on a false premise,” says Gaesser. “It’s become such a popular notion that if you Google ‘gluten-free diet’ you’ll get more than 4.2 million results. Celebrities endorse it, and there are hundreds of books being published on it.

“But the only reason you would lose weight is that you’re cutting calories. It probably won’t hurt you to go gluten-free. However, there are indications that gluten may contribute to blood pressure control and immune function, and may create a healthy composition of colon bacteria.”

A gluten-free diet often leads to weight gain because many gluten-free products contain more added fats and sugars than other products, he said.

In submitting his article for peer review by other scientists before publication, Gaesser disclosed that he is the scientific advisory board chairman of the Grain Foods Foundation. As a longtime critic of anti-carbohydrate dieting, he was asked by the foundation to review the scientific literature associated with gluten-free dieting. Afterwards he asked permission to publish the results.

“People might think I had a bias, but I couldn’t find any published literature on the health benefits of gluten-free diets for people without celiac disease, gluten sensitivity or autoimmune disorders. There should be some studies, but there are none.

“This paper is one of the first to look at the other side of the gluten craze. Far too many Americans are following the diet for reasons that simply do not make sense. It’s time to listen to the science.”