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Sci Tech
Melting million-year-old ice to study ancient microbes
Organisms that thrive in the harshest environments on the planet, ranging from the dry, frigid desert of Antarctica, to geyser-like hydrothermal vents spewing toxic chemicals from the ocean floor, called ‘extremophiles’, have long fascinated scientists.
Now, researchers from the University of Delaware and the University of California at Riverside have thawed ice estimated to be at least a million years old from above Lake Vostok, an ancient lake that lies hidden more than two miles beneath the frozen surface of Antarctica.
Hostile environment
Their mission is to study how microbes have survived in the ice and become adapted to an environment that is eternally dark, cold and so isolated that food and energy sources are likely rare and hard to come by.
The Vostok water contains only between 10-100 microbes per millilitre compared to approximately 1 million microbes per millilitre for most lakes.
The research, which is sponsored by the National Science Foundation is part of the International Polar Year. “It’s some of the coolest stuff I have ever worked on,” said Craig Cary, professor of marine biosciences at UD. “We are going to gain access to the genetics of organisms isolated for possibly as long as 15 million years.”
Segments of a tube-like ice core were thawed under meticulous, “clean lab” conditions to prevent accidental contamination.
Joint effort
The segments of ice were cut from an 11,866-foot ice core drilled in 1998 through a joint effort involving Russia, France and the United States. The core was taken from approximately two miles below the surface of Antarctica and 656 feet (200 metres) above the surface of Lake Vostok.
“This ice was once water in the lake that refroze onto the bottom of the ice sheet,” Cary explained.
“We have no direct samples of the lake itself, only this indirect sampling of the refrozen ice above it because drilling into the lake without taking extensive precautions could lead to the lake’s contamination.
The borehole made to collect the ice is filled with a mixture of jet fuel, kerosene, and CFCs to keep it from closing,” Cary noted.
“Since the lake has not had direct contact with the surface world for at least 15 million years, this would be a contamination of one of the most pristine environments on Earth,” he said.
Novel “whole genome amplification” techniques will be applied, which provide insight into the genetic diversity of a community of organisms when only small numbers of organisms are available, according to a University of Delaware press release.
Natural furnaces
In the case of Lake Vostok, scientists speculate that it stays in a liquid state underneath miles of ice due to one of the Earth’s natural “furnaces” — hydrothermal vents. Superheated water erupts from these cracks in the seafloor which form where the plates that form the Earth’s crust pull apart.
“We hope that by being so isolated for millions of years, these microorganisms from Vostok will be able to tell us about their life and conditions through the ages,” Cary said. — Our Bureau
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