Its time to dip into the animal file and I thought Id feature some local animals. Researchers at University of Guelph in Canada have discovered the type of stem cell thats behind the gecko's ability to regrow its tail, a finding that has implications for spinal cord treatment in humans.

In a study published in the Journal of Comparative Neurology, they reported that the spinal cord in a geckos tail contains both stem cells and proteins known to support stem cell growth. Geckos can regrow a new tail within 30 days, faster than any other lizard. As we all know, they detach their tails when grabbed by a predator. The severed tail continues to wiggle, distracting the predator long enough for the gecko to escape.

In the lab, the researchers pinched the gecko's tail, causing it to drop. After detachment, the body wound began to repair itself, eventually leading to new tissue formation and a new spinal cord. The scientists then investigated what happens at the cellular level before and after detachment.

They discovered that the spinal cord houses a special type of stem cell known as the radial glia which is normally inert. But when the tail detaches, the cells make different proteins and begin to divide and make more new cells. Ultimately, they make a brand-new spinal cord. Once the injury is healed and the spinal cord restored, the cells return to a resting state."

Humans respond to spinal cord injury by making scar tissue. The scar tissue seals the wound quickly, but it prevents regeneration, which is why humans have a limited ability to repair our spinal cords. Were missing the key cell types required. The researchers hope to eventually apply their new knowledge to help humans with spinal cord injuries.

A well-known danger here in our islands is divers who get the bends, a painful and potentially life-threatening decompression sickness that strikes scuba divers who surface too quickly. Did you ever wonder if whales and other marine mammals can get the bends? A new study conducted by researchers at the Woods Hole Oceanographic Institution and published in the journal Proceedings of the Royal Society examines how marine mammals generally avoid getting the bends and how they can succumb under stressful conditions.

When humans make deep dives, their lungs compress and that collapses their alveoli, the tiny lung sacs where gas exchange occurs. Nitrogen bubbles build up in their bloodstream and tissues. If they ascend slowly, the nitrogen can return to the lungs and be exhaled. But if they ascend too fast, the nitrogen bubbles don't have time to diffuse back into the lungs. Under less pressure at shallower depths, the nitrogen bubbles expand in the bloodstream and tissue, causing pain and damage.

But whales, dolphins and porpoises have unusual lung architecture which creates two different pulmonary regions which cause their lungs to partially compress. Scientists assumed that this partial compression was the main adaptation sea mammals have to avoid taking up excessive nitrogen at depth and getting the bends.

The researchers took scans of a deceased dolphin, seal, and a domestic pig pressurized in a hyperbaric chamber and discovered that blood flows mainly through the collapsed region of the lungs. That allows some oxygen and carbon dioxide to be absorbed by the animal's bloodstream, while minimizing or preventing the exchange of nitrogen. The pig didnt show that structural adaptation.

Scientists once thought that diving marine mammals were immune from decompression sickness, but a 2002 stranding event linked to navy sonar exercises revealed that 14 whales that died after beaching off the Canary Islands had gas bubbles in their tissues, a sign of the bends. The researchers think that excessive stress may cause the system to fail and increase blood flow to the air-filled regions.

This study may help explain why so many marine mammals are dying and probably also implies that we humans are to blame. I hope somebody pays attention!

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Gecko tails and whale bends | Featured Columnists - The Guam Daily Post