Exotic-looking microbes turn up in ancient Antartic ice
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Exotic-looking microbes turn up in ancient Antarctic ice
Updated, July 17 to include links to recent diatom discoveries.
March 13, 1998: Two scientists exploring a microworld locked in ancient ice have found a wide range of lifeforms from fungi, algae, and bacteria to a few diatoms - and a few items with strange shapes.
" We've found some really bizarre things - things that we've never seen before," said Richard Hoover of NASA's Marshall Space Flight Center. Hoover and Dr. S.S. Abyzov of the Russianexamining deep ice core samples from the Vostok Station about 1,000 km (620 miles) from the South Pole.
The objects have fanciful names - like Mickey Mouse and Klingon (right) - based on passing resemblances. Hoover expects that most will fall into known categories of microorganisms as he and Abyzov study the images.
"We're exploring a new world," Hoover said. "Until we get a lot more experience, we're going to see brand new things all the time."
|The ice harboring these finds is as old as 400,000
years, depending on the depth. Russian scientists at the St. Petersburg
Mining Institute in St. Petersburg, Russia, developed the technology for
drilling ice cores without contaminating the samples. Since 1974, they
have worked at Vostok Station, extracting cores from ever greater depths.
In 1996, the Russian
Academy of Sciences announced that a large lake of liquid water lies beneath
the 3 km-deep glacier at Vostok.
Meanwhile, the ice samples from above the lake's surface (which has not been breached) are stirring interest in the scientific community. In the 1970s, Abyzov discovered - and in some cases revived - microorganisms in ice that conventional wisdom had said was sterile.
"These are very important questions for future cosmic research on places like Europa, comets, the Martian ice caps," Abyzov said of the mysteries in the Antarctic ice.
|This "Mickey Mouse" shape (seen at left in the first image) is actually part of a colony of fluffy microbes buried for several thousand years in the Antarctic ice. What appears to be Swiss cheese (in the enlargements) is actually the filter through which the melted ice was drained. Electron beams drilled holes. Each of these images is linked to a 1350x1050 pixel JPG, 280K to 640K in size. Please use with the following credit line: NASA/Marshall Space Flight Center.|
"This is very useful," Abyzov said, "because we
do not have this equipment in our laboratory. We have scanning electron
microscopes, but without the additional equipment you have."
"There are some dust particles with unusual spectra," Hoover said. "Which may be cosmic dust particles." The ESEM allows the operator to designate a point on a specimen and then scan with X-rays to determine what elements are present. The ratios found in some of the dust particles do not match ratios expected in terrestrial dust grains.
"Mickey Mouse" and other colonies of small microbes appear to be out of the ordinary. These are fluffy white objects, about 1 micron wide and resembling cotton balls.
"Here's the shocker," said Hoover, pointing at the ESEM monitor, "these small coccoid bodies are covered with all this incredible fibrous structure." The filaments appear to be about 30 to 40 nanometers wide (that's about 1/10th a wavelength of visible light).
"There are all sorts of microorganisms in the ice. Some are readily recognizable as cyanobacteria, bacteria, fungi, spores, pollen grains, and diatoms, but some are not recognizable as anything we've ever seen before," Hoover said. Many will turn out to be known. It's just that they look different under the ESEM, which provides details that are not available through other microscopes.
Familiar items include bits of sponge and feather, and(right), Hoover's other area of personal interest and expertise (he works at Marshall as an X-ray astronomer).
They have also found a number of large cyanobacteria with nanobacteria attached.
"What is clearly going on is that when microorganisms freeze, they shut down and go into this anabiotic state," Hoover explained. Anabiotic means alive but inactive, like suspended animation. Russian scientists have been able to revive and culture bacteria, yeast, fungi, and other microbes found in ice cores.
"One of the things that was really exciting was that many of the cyanobacteria from 1,243 meters down had lots of antimony," Hoover said. The X-ray spectrum showed carbon, oxygen, zinc, silicon, aluminum, and potassium - all chemicals common to life. But it also showed an abnormal amount of antimony, a toxic heavy metal.
"It was not just one of these that had it," Hoover said, "but microorganism after microorganism."
Gregory Jerman, the ESEM operator, noted that the metal content has varied with depth. At some levels the microorganisms show large quantities of antimony, while in others zinc rings the bell
|More unusual shapes found in the Vostok Station ice resemble a porpoise, Thanksgiving leftovers, and a sphere. These names will give way to proper scientific names as Hoover and Abyzov identify them in the coming months. Each of these images is linked to a 1350x1050 pixel JPG, 280K to 640K in size. Please use with the following credit line: NASA/Marshall Space Flight Center.|
As Hoover talked, another new image appeared on screen.
"It's pretty big," he said of an object that looked like a porpoise (above) and probably is a protozoan.
"The work of identifying and classifying everything in the ice will be long and challenging," Hoover said. He compared it to his own initiation in the world of diatoms where for years everything looked new until he became familiar with it. Then he could quickly recognize the rare unusual specimen.
"It's necessary to know what to look for and the kinds of things you can see," he said.
Like the Klingon's forehead, a wrinkled object resembling a character from Star Trek, or the porpoise. For now some of them just have nicknames, until Hoover, Abyzov, and their colleagues analyze their exciting images and obtain more definitive identifications of these microscopic beasts of the frozen underworld..