Salamander's Regenerative Abilities

photo courtesy:  National Geographic

Salamanders are amphibians with superficially lizard-like appearance. They have slender bodies, short noses, long tails. their life on habitats in and or or around water is added by their moist skin. Some salamander species are fully aquatic throughout life, some take to the water intermittently, and some are entirely terrestrial as adults. one striking capability of salamanders, that is unique among vertebrates, is regeneration of lost limbs, as well as damaged lungs, sliced spinal cord -- even bits of lopped-off brain. Biologists have been researching since past few years on this attribute of these creatures and some surprising results have come. let's check out.

July 2, 2009 — 

Scientists had long credited the small amphibious creature's out-sized capabilities to "pluripotent" cells that, like human embryonic stem cells, have the astonishing ability to morph into whatever appendage, organ or tissue happens to be needed for a replacement.The salamanders heal perfectly, without any scars.

A paper set to appear on July 2 in the journal Nature by a team of seven researchers states the following. Based on experiments on genetically modified axolotl salamanders, the researchers show that cells from the salamander's different tissues retain the "memory" of those tissues when they regenerate, contributing to the same type of tissue from whence they came.

Standard mammal stem cells operate the same way, although with far less dramatic results -- they can heal wounds or knit bone together, but not regenerate a limb or rebuild a spinal cord. What's exciting about the new findings is they suggest that harnessing the salamander's regenerative wonders is at least within the realm of possibility for human medical science.  

"If you can understand how they regenerate, then you ought to be able to understand why mammals don't regenerate," one of the scientists said.

Dec. 9, 2009 — 

For more than 400 years, scientists have studied the amazing regenerative power of salamanders, trying to understand how these creatures routinely repair injuries that would usually leave humans and other mammals paralyzed -- or worse.

A multi-institutional team of researchers associated with the University of Florida McKnight Brain Institute's Regeneration Project has begun creating genomic tools necessary to compare the extraordinary regenerative capacity of the Mexican axolotl salamander with established mouse models of human disease and injury.

Researchers want to find ways to tap unused human capacities to treat spinal cord injury, stroke, traumatic brain injury and other neural conditions. 

The axolotl is the champion of vertebrate regeneration, with the ability to replace whole limbs and even parts of its central nervous system.These salamanders use many of the same body systems and genes that we do, but they have superior ability to regenerate after major injuries. We think that studying them will tell us a lot about a patient's natural regenerative capacities after spinal cord injury and nerve cell damage.

Dec. 15, 2009 —

The most comprehensive study to date of the proteins in a species of salamander that can regrow appendages may provide important clues to how similar regeneration could be induced in humans.

Researchers at the School of Science at Indiana University-Purdue University Indianapolis and colleagues investigated over three hundred proteins in the amputated limbs of axolotls, a type of salamander that has the unique natural ability to regenerate appendages from any level of amputation. this could contribute to a better understanding of the mechanisms that allow limbs to regenerate. 

"Comparison of these proteins to those expressed in the amputated frog limb, which regenerates poorly, will hopefully allow us to determine how we might enhance limb regeneration in the frog and ultimately in humans", Dr. Stocum said.

With few exceptions -- notably the antlers of moose, deer and their close relatives, the tips of the fingers and toes of humans and rodents, and the ear tissue of certain strains of mice and rabbits -- the appendages of mammals do not regenerate after amputation.

Investigating the proteins found in the axolotl limb, the researchers noted three findings that appear to have significance in reprogramming cells to grow new limbs:

1. Quantities of enzymes involved in metabolism decreased significantly during the regeneration process.

2. There were many proteins that helped cells avoid cell death. Because amputation is very traumatic, this is 

    critical.             .                                              

3. A protein which appears to keep cells from dividing until they are fully dedifferentiated and reprogrammed  

    to begin forming a new limb was expressed at high levels throughout blastema formation.

Salamanders also seem to be possessive mothers. Read on this article.

Dec. 6, 2010 — 

Don't get between a salamander and her eggs, particularly as the eggs get closer to hatching. A study has found that female salamanders grow more aggressive in defending their nests as their eggs mature. 

An article in the December 2010 issue of the journal Herpetologica describes the behavior of the eastern red-backed salamander, found in forests of North America. The females proved to be more vigorous about guarding clutches of eggs than territory or food.

These salamanders have the ability to recognize the developmental stage of their eggs, or at least are able to determine the amount of time that has passed since they laid their eggs. The older the brood, the more likely it is to survive to hatching, making it more important to the mother.