Class blog for sharing and commenting on current events in biology.

Thursday, February 7, 2013

Bacteria Found Deep Under Ice, Scientists Say, Opening New Antarctic World

Matthew Bettino                                                                                                                                                2/6/13
Block C Davies

                  The Antarctic ice sheet is the largest single piece of ice on the planet. Recently, the National Science Foundation of America invested $10 million into ice drilling in the Antarctic. The goal of these drilling expeditions is to locate and drill to lakes under the thick sheet of ice. About half a mile under the surface of the ice sheet is a system around one hundred lakes. These lakes are wedged in between the continental crust and the ice sheet on top. Lake Whillans was one of these lakes. Lake Whillans spans about 23 square miles and is about 5 feet deep. When the US drills finally reached this lake, scientists discovered mind-changing things. Half a mile below a pure sheet of ice lives bacteria. The inhabitants of Lake Whillans were chemically tested and were found to be fully alive. This discovery changes the way scientists understand the possibility of extraterrestrial life forms. Down in these deep, cold conditions, the bacteria have no access to light. Therefore, to obtain the necessary energy to metabolize, the bacteria are forced to rely on another source. Scientists determined that these bacteria were consuming the decaying remains of microbes found in the receding glaciers. However, Chris McKay of NASA said the bacteria would be of even more interest if they were consuming another body of energy. One clue of life that led to the discovery was the location of DNA in cells they observed. The DNA that has been collected is still to be analyzed. Scientists are hopeful that the DNA testing will shed even more light on the topic of sub-ice creatures and their relationship with extraterrestrial life.
            This discovery is important to science because it gives scientists more evidence that life can thrive under extreme conditions and without sunlight. An example similar to this discovery was one made under the ocean. On our trip to the Museum of Natural History in Earth Science, we came across an exhibit about black smokers or underwater sea vents. These vents are located so deep in the ocean, scientists believed that the pressure, temperature, and lack of light would not allow for life to survive. However, a whole ecosystem was discovered around the smokers. The life living down there used chemosynthesis, a process of using the chemicals produced by the black smokers to create necessary energy. This discovery showed scientists how life could survive without access to things humans and other surface organisms need to survive. This discovery of bacteria living deep under ice depicts another way life can survive under extreme conditions. The ability of life to adapt and survive based on its environment has led scientists to believe that life could survive on other planets in or solar system or beyond. I chose this article because I am very interested in astronomy and the possibility of life beyond our knowledge. This topic has limited information available to use as proof. It is exciting when I hear that scientists took another step in the direction of determining how extraterrestrial life could survive.
            I thought that this article was well written. The author explained details in understandable terms and clearly showed how the discovery was important to science. However, the article was written in a way that the facts and data collected were presented first, while the actual process came second.  I think that the details about funding and set-up of the operation should have followed the brief summary of what was discovered. The more pinpoint details should have followed. Also, the description of the DNA found in the lake was jammed in at the end of the article. This information seemed to be relevant and interesting. I wish the author would have spent more time discussing the discovery and possible importance of the DNA collected in Lake Whillans. Overall, I really enjoyed reading this article. It enriched the knowledge I already possess on a topic I really enjoy.

Gorman, James. "Bacteria Found Deep Under Antarctic Ice, Scientists Say." The New York Times. The New York Times, 07 Feb. 2013. Web. 06 Feb. 2013.
Bacteria Found Deep Under Ice, Scientists Say, Opening New Antarctic World
Published: February 6, 2013
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For the first time, scientists report, they have found bacteria living in the cold and dark deep under the Antarctic ice, a discovery that might advance knowledge of how life could survive on other planets or moons and that offers the first glimpse of a vast ecosystem of microscopic life in underground lakes in Antarctica.
Dr. Alberto Behar, JPL/ASU; underwater camera funded by NSF and NASA
The first view of the bottom of subglacial Lake Whillans in Antarctica.
A network of hundreds of lakes lies sandwiched between the continent’s land and the ice that covers it, and scientists had thought that it could harbor life. The discovery is the first confirmation.
“It transforms the way we view the Antarctic continent,” said John C. Priscu of Montana State University, a leader of the scientific expedition.
After drilling through a half-mile of ice into the 23-square-mile, 5-foot-deep Lake Whillans, the expedition scientists recovered water and sediment samples that showed clear signs of life, Dr. Priscu said, speaking from McMurdo Station in Antarctica on Tuesday. They saw cells under a microscope, and chemical tests showed that the cells were alive and metabolizing energy.
Dr. Priscu said that every precaution had been taken to prevent contamination of the lake with bacteria from the surface or the overlying ice. In addition, he said, the concentrations of life were higher in the lake than in the borehole, and there were signs of life in the lake bottom’s sediment, which would be sealed off from contamination.
Much more study, including DNA analysis, is needed to determine what kinds of bacteria have been found and how they live, Dr. Priscu said. There is no sunlight, so the bacteria must depend on organic material that has drifted into the lake from other sources — for instance, decaying microbes from melting glaciers — or on minerals in the rock of the Antarctic continent.
Chris McKay, a NASA senior scientist, said in an e-mail that such analysis could determine if the bacteria in Lake Whillans have implications for the possible discovery of extraterrestrial life. “If it was using a local energy source, it would be interesting,” he said. “If it’s just consuming organics carried in from elsewhere, it is of much less interest.” The reason, he said, is that elsewhere in the solar system where there is good evidence of liquid water under thick ice sheets, life would have to depend on minerals alone. “There is not going to be oxygen on other worlds,” Mr. McKay said.
Slawek Tulaczyk of the University of California, Santa Cruz, another leader of the science expedition, said that samples were drawn from as deep as four feet in the sediment, and that oxygen decreased with the depth of the sample.
The scientific project, called Wissard, for Whillans Ice Stream Subglacial Access Research Drilling, was years in the planning and is one of three efforts to investigate the lakes that lie under the Antarctic ice.
A year ago, a Russian expedition penetrated the surface of Lake Vostok, under two miles of ice. They found hints of life on samples from the drill bit, but contamination from the kerosene drilling fluid was a possibility. This year they recovered samples of frozen lake water that are yet to be analyzed.
A British effort to reach Lake Ellsworth, under a mile of ice, was called off in December because of equipment problems.
The American effort, supported by $10 million from the National Science Foundation and other grants, focused on Lake Whillans, which is quite different from the other two lakes. It lies under a half-mile of ice, less than the others, and its water is replenished in about a decade, scientists believe, with meltwater from overlying ice. Lake Vostok is much more sealed off from the surface and is thought to take 10,000 years for its waters to renew. Lake Ellsworth may turn over in about 700 years.
Although Lake Whillans may be more reachable than the other two, doing anything in Antarctica is enormously difficult. It took a tractor convoy 12 days to take the drill and other equipment more than 500 miles over the Ross Ice Shelf to the drilling site from the American research station at McMurdo.
The scientists had four days to collect samples and obtain images of the lake. Several lines of evidence convinced them that they had found microbial life in the lake. First, they saw cells under the microscope and confirmed that DNA was present.
Then they measured evidence of an enzyme that is important in metabolism and a chemical called ATP, for adenosine triphosphate. Molecules of ATP are essentially packets of energy, and their presence was a further indication that the bacteria were living. Further, they found that concentrations of ATP were higher in the lake water than in the water in the borehole, which, Dr. Priscu said, meant that there was more life in the lake and argued against any contamination.
Much further study will be done before scientific results are published and other scientists can look at all the data. Dr. Priscu said that new tests were being done each day, but that DNA tests would have to wait until the scientists returned to the United States.
“Our stateside DNA sequence work will tell us who they are,” he said of the microbes, “and, together with other experiments, tell us how they make a living.”
But he said he was confident that the researchers had achieved the first glimpse of an ecosystem that had been completely unknown. “It’s the world’s largest wetland,” Dr. Priscu said.

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