Sunday, June 21, 2009

Salamander can regrow spinal cord; has genetic map 10 x size of humans

From the gardens of Xochimilco:

Mexican salamander may yield clues for amputees
Jun 17, 2009
By Mica Rosenberg

MEXICO CITY (Reuters) - Scientists are genetically modifying a bizarre looking Mexican salamander, which according to ancient mythology is a transformed Aztec god, in the hope its ability to regenerate body parts will one day help human amputees.

Also known as "water monsters," the half-foot-long (15-cm-long) axolotl is nearly extinct in its only remaining habitat: the polluted vestiges of Aztec canals that snake though southern Mexico City, packed with colorful boats carrying tourists and mariachi musicians.

But the slimy animal crowned with frilly gills like a headdress, beady eyes and a goofy smile, is thriving in labs where it reproduces easily. It is a darling of researchers since it can regrow injured limbs, jaws, skin, organs and parts of its brain and spinal chord.

Some other animals have the capacity to regenerate, but only salamanders can regrow so many different parts over and over again throughout their lives.

The U.S. Department of Defense has given a $6.25 million research grant to scientists studying the little creature with the aim of eventually helping the more than 1,000 soldiers who have come back from Iraq and Afghanistan with missing extremities.

In a lab in Mexico City, where biology students map the shrinking habitat of the animal, an axolotl whose leg was recently bitten off by a tank mate was already budding a tiny replica, complete with little toes.

"Humans do repair tissue but they don't repair it perfectly whereas the axolotl under certain injury conditions can go into kind of a mode where they repeat the process of the embryo," said Elly Tanaka from the Center for Regenerative Therapies in Dresden, Germany.

Tanaka has succeeded in genetically engineering axolotls using a mutant type found in the wild with no skin pigment and inserting a green-glowing gene from a jellyfish into the salamander cells to help see the process of regeneration in action.

"The skin is clear so you can see the fluorescent protein inside the live animal," Tanaka said in a phone interview. The goal is to compare and contrast with the human healing process.

After amputation in salamanders, unlike in humans, blood vessels contract quickly and limit bleeding, skin cells work fast to cover the wound site and form what is called a "blastema," a collection of stemlike cells that will eventually become the new body part.

Working alongside scientists mapping the complex genome of the axolotl, which is 10 times larger than a human genome...

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