Vampire bats could hold key to nervous system
Published 1:54 pm, Friday, August 5, 2011
(08-05) 13:54 PDT SAN FRANCISCO -- From "Dracula's" Bela Lugosi to "Twilight's" Bella Swan, human vampires have nothing on vampire bats, whose blood-sucking talents are giving scientists new insights against some of the most painful nervous system disorders that humans can suffer.
In a laboratory at UCSF and from the wilds of Venezuela, researchers have discovered how evolution has endowed wild vampire bats with a unique weapon that enables them to zero in for a ravenous feed on the warmest blood vessels of their prey.
It's well known that bats can pinpoint their prey by emitting their chirps and squeaks like sonar as they fly to spot a tempting target meal by analyzing its returning echoes.
But vampire bats are different: they don't fly, they run to any animal or unwary bird whose blood will sate their hunger, and they are uniquely far more specialized than other bats, according to David Julius, a distinguished neurophysiologist at UCSF.
Julius and his lab colleagues have discovered that vampire bats - Desmodus rotundus - possess unique heat-sensitive molecules within specialized nerve endings on the surface of their noses - molecules that detect infrared radiation signals from the heat of blood as it flows close beneath the skin of a prey's veins and arteries at about 86 degrees.
The best source of that heat radiation comes from accessible regions of a victim animal's skin where fur or feathers don't impede the flowing blood's signal - and that's just where the vampires prefer to dine, sipping about a teaspoon of blood at a time.
Julius, and Elena O. Gracheva, a post-doctoral fellow in his lab, have been working to understand the genetic basis of the specialized nerves that are sensitive to heat in both humans and animals. Last year, they and their colleagues reported discovering a different infrared-detecting molecule in varied pit vipers, including the Pacific rattlesnake, familiar to all Sierra hikers.
After that work Julius and his lab colleagues sought to look for similar nervous system molecules in vampire bats, as he recalled in a conversation Tuesday. "But we didn't know where to find them," he said - until Julio F. Cordero-Morales, another post-doc in his lab, said he knew a research team in Venezuela whose members were studying the bats.
Promptly the Caracas group collected samples of nerve cell masses from the noses of wild vampire bats, shipped them to San Francisco in dry ice, and the Julius team went to work. They fixed some samples with formaldehyde and homogenized others to sequence their genes.
The nerve cells they studied are similar to the molecules in human nerve fibers that give people acute sensitivity to the sensation of heat like that which comes from eating chili peppers and spicy foods containing the heat-emitting chemicals called capsaicins.
Analyzing the genes involved in heat sensitivity among animals like snakes and vampire bats is also leading Julius and his colleagues to study the possibility of new approaches to pain relief in humans, he said.
The nerves the researchers are studying in bats and snakes are akin to nerves in humans that cause such pain in nerve disorders like trigeminal neuralgia, a chronic pain condition that affects the trigeminal nerve, which carries sensation from face to brain.
Julius is on the advisory board of a company called Hydra Biosciences, of Cambridge, Mass., which seeks to develop novel drugs to treat pain, inflammation and other disorders based on the types of so-called "ion channel" nerve structures involved in the Julius lab's research.
His lab's new discovery in vampire bats is published today in the journal Nature.
This story has been corrected since it appeared in print.
E-mail David Perlman at email@example.com.