This week's In the News focuses on discoveries that provide support for the theory that deep sea hydrothermal vents may have been the "factories of life" three and half billion years ago when Earth's atmosphere did not consist of any oxygen. A recent article published in Science (February 5, 1999, 283:831-833) discusses how scientists at Nagaoka University created an environment similar to a submarine hydrothermal system. Submarine hydrothermals are transition zones where hot water rises from a vent into the cold environment of the surrounding water. The hydrothermal vent sites are termed "black smokers" or sulfide chimneys and are formed when heated water containing metals and volcanic gases rises into the cold deep ocean from hot regions below the seafloor. These scientists added fluid containing the amino acid, glycine, to the simulated environment. They found that glycine polymerizes (one unit is added to the amino acid in a step-wise manner) in the hot region, is released into the cold region where its bonds are solidified, and re-enters the hot region and polymerizes again. The heat from the hot region drives this reaction. The repeated circulation of glycine through the hot and cold water regions of the simulated hydrothermal vents created oligopeptides of glycine. It is suggested that "life probably started with organic chemicals forming into amino acids...from which the first hydrogen-consuming microbes emerged"(3). Researchers at the Carnegie Institution's Geophysical Laboratory suggest that ammonia (NH3) production occurred in early Earth's crust and in hydrothermal vents. Furthermore, organic chemicals such as nitrogen and hydrogen are necessary to form amino acids, which are the basic components of living things. Chris German, of the Southampton Oceanography Centre, spotted a "a hot spring more than 9,000 feet under the Atlantic Ocean where a volcanic vent poured out hydrogen and provided conditions for hydrogen sulfide oxidizing microbes" to survive. Life forms such as giant clams, pale mussels, white crabs, and Pompeii worms (Nature, 1998, 391:545-546) have also been found on these sulfur chimneys. These creatures are dependent on bacteria, which use hydrogen sulfide from vent water as a primary energy source. Scientists hope that studying these ecosystems may shed light on the origin of life on Earth as well as on other worlds in our solar system. The nine resources listed provide background information and insights into these discoveries.
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