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5 December 2013 11:26 am ,
Vol. 342 ,
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
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...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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New Mode of Cell Communication Discovered
9 January 2008 (All day)
Like teenagers, cells in our bodies constantly chatter back and forth. But instead of zapping text messages, they relay signals with molecules. Now, researchers have discovered a surprisingly tiny new messenger in worms: protons. The find raises the possibility that the subatomic particle plays the same role in humans, the researchers say.
Research in mice has hinted that protons--hydrogen atoms stripped of their electrons--might act as messengers, but until now direct evidence has been lacking. A team led by biologist Erik Jorgensen of the University of Utah, Salt Lake City, made the discovery while investigating how the worm Caenorhabditis elegans contracts certain muscles around its intestines to squeeze out waste. Previous experiments had ruled out several neurotransmitters known to aid defecation, suggesting that a novel molecule might be playing a role.
After sequencing the DNA of worms with defects in muscle contraction, the team identified mutations in a gene called PBO4. This gene encodes a protein located on the outer surface of intestinal cells, where it brings sodium ions into the cell while pumping protons out. This hinted that protons might play a role in making the muscles contract.
Next, using a protein that glows green until it contacts protons, the researchers found that protons flood from the intestinal cells and into the surrounding muscle cells just before the muscle contracts. Finally, the researchers inserted protons bound to a light-sensitive molecule into the space between the intestine and the muscle in mutant worms with a defective PBO4 gene. When a flash of light set the protons free, the muscle contracted, the researchers report in the 11 January issue of Cell. Further experiments identified a receptor on the muscle cells that triggers contraction when protons bind to it.
Jorgensen speculates that protons probably act as neurotransmitters in humans and other vertebrates, but so far there is no evidence of this. He notes that this could explain why humans have proton pumps in brain cells that are the same as the proton pumps found in their intestines.
Les Iversen, a neuroscientist at the University of Oxford, U.K., agrees with that notion. But Charles Stevens, a neurobiologist at the Salk Institute for Biological Studies in San Diego, California, says that the protons may only be used as neurotransmitters in worms and other invertebrates. "Oftentimes, invertebrates have evolved special mechanisms that are not so widely used in vertebrates," Stevens says.