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The Search for Alien Life, a Search for CelluloseCellulose, evidence of ancient life form existence |
By Gabriel Gache, Science News Editor
31st of March 2008, 07:46 GMT
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According to University of North Carolina researchers, the search for extraterrestrial life forms does not necessarily require the find of the actual life forms. Evidence of its existence could be just as rewarding. They reveal that life on Earth could have actually appeared 200 million years
earlier than previously believed.
One of the most abundant biological material produced by plants, algae and bacteria on Earth is cellulose. It is estimated that plants produce annually about 100 gigatons of this tough, resilient substance. Cyanobacteria such as the blue-green algae and bacteria which existed 2.8 billion years ago should have been able to produce some forms of prehistoric cellulose, which still exist in some areas of the world even today.
For example, cellulose microfibers were found by Jack D. Griffith, Ph.D, Kenan Distinguished Professor of microbiology and immunology at UNC School of Medicine, in ancient salt deposits deep beneath the New Mexico desert. "The age of the cellulose microfibers we describe in the study is estimated to be 253 million years old. It makes these the oldest native macromolecules to date to have been directly isolate, visualized and examine biochemically," said Griffith.
Previously, the oldest biological material ever found was in a Tyrannosaurus Rex dinosaur fossil, in the form of an ancient protein fragment and dated to be about 68 million years old. Griffith believes that some of the earliest life forms could have developed processes to polymerize glucose in cellulose. "Cellulose is like the bacteria's house, the biofilm surrounding them. Plants adopted cellulose as their structural entity, and insects changed cellulose slightly to make chitin of which their exoskeletons are formed," said Griffith.
In order to collect data for his study, Griffith had to obtain samples from the U.S. Department of Energy's Waste Isolation Pilot Plant. The WIPP is a radioactive waste underground facility, located in a room excavated in salt, 600 meters underground, located near Carlsbad. The salt deposits were created more than 200 million years ago and the location was chosen as radioactive waste deposit, due to the fact that salts flow in a plastic way, to seal off any eventual cracks which may develop with the passing of time.
Salt samples from the WIPP revealed microscopic bubble inside the crystals, containing high amounts of cellulose microfibers. "The cellulose we isolated from the ancient salt deposits is very much like real, modern day cellulose: it looks like cellulose, behaves like cellulose, it's copped up by the same enzymes that cut modern day cellulose and it's very intact," says Griffith.
Griffith believes that looking for life on Mars would pretty much involve searching for evidence of cellulose in salt deposits. Opposed to DNA, cellulose is much more resilient and more stable while being subjected to ionizing radiation, which makes it ideal in the search for life elsewhere but on the Earth.
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