"It's not surprising that no one has really heard about them; archaea have still not even penetrated mainstream biology textbooks," said David Relman, MD, associate professor of medicine (infectious diseases) and of microbiology and immunology. There are, however, at least as many of them as there are bacteria, he said.
Archaea look a lot like bacteria, but appearances can be deceiving. Genetically and biochemically they are as different from bacteria as bacteria are from humans. The microbes live in many extreme environments - from hot springs to salt lakes to submarine volcanoes - but also within animals, including the human colon, vagina and mouth.
"To me it is one of those fundamental puzzles: they are everywhere and, given that we must be exposed to them somewhat frequently, if not all the time, why is it that we can't name one disease-causing member of this enormous domain?" Relman wondered. He and his group at the Veterans Affairs Palo Alto Health Care System have shown a never-before-known connection between the abundance of archaea and the severity of a human gum disease called periodontitis.
Chronic periodontitis, which affects about one-third of Americans, may result in tooth loss and is thought to play a role in a range of conditions including atherosclerosis, stroke and early delivery of low birth-weight infants. While there is a general consensus that bacteria play a role in gum disease, no single microbe has been implicated as the culprit.
Relman and members of his lab embarked on a comprehensive, controlled study of the archae
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Contact: Mitzi Baker
mitzibaker@stanford.edu
650-725-2106
Stanford University Medical Center
22-Apr-2004