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the news hound yet again. is it just me, or are these profound types of discoveries turning up faster and faster? janet --------------------------------------------------------------------------- Study confirms existence of third major branch of life --------------------------------------------------------------------------- Copyright 1996 Nando.net Copyright 1996 The Associated Press WASHINGTON (Aug 22, 1996 7:23 p.m. EDT) -- Scientists have decoded the genes of a microbe that lives on the ocean floor, can survive only in near-boiling water and thrives on carbon dioxide. The study confirms existence of a third major branch of life, experts say. A team of researchers from three institutions announced Thursday that they decoded the 1,700 genes of a microbe called Methanococcus jannaschii and found that it is a member of a branch of life called archaea. "This is a very different life form from what we know," said J. Craig Venter of the Institute for Genomic Research, the senior author of a study to be published Friday in the journal Science. "Two-thirds of the genes in this organism are new to science and biology," Venter said. This finding, he said, proves that the microbe is a member of a class different from the two other basic branches of life -- bacteria and eukaryotes, which include plants, animals and humans. Cellular structure is the main difference between these forms of life. The cells of eukaryotes have nuclear structures. Bacteria do not. The archaea has some characteristics of the other life forms, but is fundamentally different in the way it functions and lives, said Venter. The existence of archaea as a third branch of life was first proposed by Carl Woese and Ralph S. Wolfe of the University of Illinois, Urbana, in 1977. Their conclusion was greeted with skepticism and only recently has it gained acceptance as more and more of the strange new form of life has been found in places where no other type of life can survive. Archaea include microbes that live at the extremes of the planet -- the very, very cold, hot or high pressure places that no other form of life could endure. "When the usual organisms start dying, then these start singing," said Venter. Some scientists have suggested that archaea may represent the earliest form of life and that it may be the most likely form of life existing on other planets. Its precise position on the tree of evolution is still uncertain, said Venter. The Methanococcus jannaschii is a microbe that was discovered living on the edge of a volcanic vent on the floor of the Pacific Ocean in 8,606 feet of water. It requires temperatures of 185 degrees F, just 27 degrees from boiling, and must be in pressures of about 3,700 pounds per square inch. Unlike most bacteria and all plants, animals and humans, the M. jannaschii lives without the direct or indirect effects of sunlight and without organic carbon as a food source. The microbe lives on carbon dioxide, nitrogen and hydrogen expelled by the volcanic vent and gives off methane, or natural gas, as a waste. To study the microbe, Woese and his associates at the University of Illinois constructed steel vats that kept the organism at high pressure and temperatures and vented away the explosive methane. "Just to keep them alive in the laboratory presented a considerable challenge," said Venter. The Illinois researchers extracted DNA from the microbe and Venter and his team then decoded the 1,700 gene structure. Researchers from Johns Hopkins University also participated in the study. About 500 species of archaea are now identified and Venter said there may be a million others. The life form is thought to produce about 30 percent of the biomass on Earth, much of it in the Antarctic Ocean. M. jannaschii is capable of digesting and concentrating heavy metals and can produce methane, a natural fuel. For these reasons, the Department of Energy is funding research on the organism. Deputy DOE secretary Charles Curtis said that his agency is sponsoring studies of 10 other bacteria and archaea that may help clean up heavy metal waste and produce sources of energy. Science, which published the study, is the journal of the American Association for the Advancement of Science. [log in to unmask]