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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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A Fishy Recipe for Healing Nerves
5 August 2005 (All day)
Unlike people, fish can regrow damaged nerve fibers in their central nervous systems. Now a study may have found the reason: The creatures lack a protein called Nogo-A that prevents nerve regeneration in mammals.
Axons, or nerve fibers, are the transmission lines that conduct electrical signals throughout the body. The fibers are protected by sheaths of myelin, a fatty insulator that speeds the electrical impulses along. Damaged axons in the brain and spinal cord of mammals don't regenerate, and spinal cord injuries can therefore lead to permanent paralysis. Fish are luckier: They can regrow the axons in their central nervous system, but curiously this regeneration stops if their nerve endings come into contact with mammalian myelin.
Because a protein in mammalian myelin called Nogo-A is known to inhibit central nervous system axon growth in mammals, a team of researchers led by biologist Claudia Stürmer at the University of Konstanz in Germany wondered if fish might be missing this protein. When the researchers exposed goldfish axons to rat Nogo-A, the nerves stopped growing. Furthermore, a comparison of genomes between ten species of fish, including zebrafish and pufferfish, and humans revealed that fish lack the genetic information to make Nogo-A or a similar inhibitor. The team reports its findings in the August issue of Molecular Biology and Evolution.
The paper's careful study of fish phylogeny supports an existing notion that Nogo-A may be a recent evolutionary development that correlates with more complex nervous systems and more complex functions, says Stephen Strittmatter, a neurologist at Yale University in New Haven, Connecticut. "It's an important addition to our growing understanding of the role these inhibitors play," he says.